Subject: Re: [teres] progress report/platter Date: Thu, 23 Mar 2000 02:58:46 -0700 From: phclark, phclark To: teres@aiko.com My principal computer has been pronounced in extremis. About the only plus to this is that I finally broke down (since my DSL doesn't work) and used another machine to access Chris' site for the pix. Frankly, I don't see what the excitement is about. There will be inevitible diffraction effects, even with translucent material. The bubbles are a local phenomenon, the bulk of which will not appear in production. I will be a happy boy if this is as bad as it gets. This project is still superior bang for the buck. As for the 3," I, too, think that it would be preferable, even at some increase in price and would participate if the option were made available. The point has been made, and correctly so, about freezing the design. It *has* to be done at some point. The membership of the List and participants, while they must and do have legitimate input, are not running this show. The administrative headaches of dealing with solder fume-crazed 'philes must be incredible. Give Chris, Bryce, Thom et al. a break, we have to trust their judgment and respect their time and efforts. Additionally, has anyone speculated on possible "constrained layer" effects of laminated extrusion as distinguished from monolithic casting? The analogy is inexact, but MDF is denser on its surfaces that in its center. When it is laminated there is a variation in density that might well prove to have beneficial damping effects (might also reflect vibration, too.) Just a thought. My $0.02. Peter C Alvin Richardson wrote: > > My $0.02 worth..I'm excited! The 3x1" acrylic platter looks okay. If the 3" > can be gotten, I am all for it! I'm not J.P. Getty, but I think the little > extra $ will be worth it. I also favor the SPJ table as a model/muse(?) of > sorts (So, what! A very talented woman designed it!?!). (Yes, I've seen the > S'phile, great pic!!) If there are some on the list who may be leaning in > that direction, building the subchasis in the same manner or similar, I > would like to throw my lot in with them and figure out the basic dimensions. > Gaudy or Baroque not withstanding, it seems to be a great table at > especially what we will be paying for it! I believe the retail for it is in > the mid teen's. (I hope to find a Wheaton Triplanar or Moerk arm for my use, > if it can be found). I have no problem if the project has to be pushed back, > timewise. Also, there were some who favored a cylindrical motor housing...I > would like to "look over your shoulders" to get ideas for material to > build/(damp) the motor pod into for housing the motor on my table. Chris, > Bryce and Thom, hang in there, great work! Let's press forward! > Regards, > al r. > ______________________________________________________ > Get Your Private, Free Email at http://www.hotmail.com Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 14:59:55 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/23/00 08:27, Stanley Goudge at sgoudge@cisco.com wrote: > Thanks Steve for your open and honest remarks, sometimes I like to shake the > bush a bit, so to speak, to find out what others are really thinking or > desire, this way we can arrive at a general consensus maybe before Christmas. > You are welcome. If you want candor from me, all you need do is ask a question. I am liable to speak my mind at any moment. Regarding concensus by Christmas -- you *are* a starry-eyed idealist, Stan! 8^) > The many versions of Teres on Chris's web site look great, if fact they look > so good that I'd love to more design types. > Just wait a few minutes, I am sure you will see some. > Opens designs seem to me the current trend and I view this as a evolutionary > process which started with the enclosed suspended subchassis (Linn) then onto > the plintless designs (VPI, Basis) now the open designs (Spj, Simon York, > ClearAudio) which seem to have achieved higher levels of performance. Somewhere out there, there may exist "the best" turntable design. Stereophile and TAS seem to discover it every month. > Plus > they use less materials which should be more economical without performance > loss, and done right we'll have performance gain at a lower cost, now that's > evolutionary! Yeah, I just had a brainstorm -- this turntable design stuff isn't so hard. We just take a big block of acrylic and remove everything that doesn't look like a turntable! Viola! (not to be confused with the musical instrument of the same name). Seriously, though I don't subscribe to the notion that measurements tell it all (else we'd all be listening to Japanese solid state amps that measure flat from DC to light), in the case of a turntable we are dealing primarily with readily explainable and understandable physical phenomena when we list the criteria for function: unvarying speed, and zero extraneous vibrations presented to the stylus/generator interface. What else am I forgetting? That our understanding of the complex interactions of materials is imperfect compounds our approach to solving the problem and may take us down some wrong paths. But I submit the more we know about the experentially verifiable properties of materials, the closer we get to making some correct decisions. We obviously have eliminated large catagories of materials as unsuitable for chassis construction: oatmeal, water above 0 degrees C, horsefeathers. . . Absurd, perhaps, but though we didn't articulate the process of analysis we haven't (yet) considered these materials because we "know" that they would be less than satisfactory. Further, we have identified that we don't want relative motion, however slight, between parts of our turntable, hence a very rigid and dimensionally stable material and geometry is desirable. We don't want vibration, or energy that might manifest itself as vibration, to be originated or propagated by any one part of our turntable to another to the maximum extent possible. So, (I think) we want structurally rigid material that is inherently dead or inert, and we want to dampen it as much as possible. External vibrations haven't explicitly been discussed yet, other than some mention in passing of sandboxes and air bladders. How best to accomplish this (vibraplane in a vacuum vessel?) in an economical manner. One solution is likely not to fit all, since we have project members living on concrete slabs and on suspended frame floors. For my part I have been cracking the old physics and engineering texts that have been unopened on my bookshelf for too long and have been trying to learn as much as I can about material properties, vibration and noise control, acoustics, motors, power transmission, etc etc. So I've posed a bunch of questions and topics. Some of the tools that I submit will help us make informed decisions have already been mentioned. Manfred's analysis of the vibration of his motor, pod and mounting arrangement was elegant in its simplicity: place the stylus of the very signal generator we are worried about -- the cartridge -- on the bare platter and run the motor with the belt off. Can we hear it? There has been mention of using a surplus phono cartridge to do vibrational analysis of various locations on the structure of the turntable. One project member posted some values of transmissive index IIRC. This is great. We need to collect this information and post it to the group, or at least the URLs and sources of the literature so we all can become educated. Our intuitive analysis of oatmeal and horsefeathers worked rather well in eliminating these materials from consideration. However, intuition fails me completely when trying to evaluate other materials much closer in properties to what we may want -- Corian, acrylic, granite. Brass, aluminum, stainless steel. MDF. Isodamp. Which is best for our application? Examination of the materials and methods used by other endevours with similar concerns as ours -- vibration control, speed control, structural integrity -- may answer some of our questions. At present I don't know enough to pretend I have the answer. I have heard some anecdotal evidence and read some interesting theories. I have also waded through some questionable arguments for or against certain materials and postulating some suspect physical explanations of the way things work. The audio field is full of ex post facto justifications or explanations, but I am thinking we can do better than that. Personally, I fully expect to try several different chassis configurations, perhaps as radically different as a heavily damped, welded steel inverted dish-with-arms for tonearm mounts, to a MDF/Isodamp/Corian laminated slab with acrylic discs for tonearm mounts. But I am hopeful that if we subject our materials and designs to as rigorous an analysis as we are capable, we might not have to go through endless iterations searching for the magic combination. This process worked very well in arriving at a bearing design and a platter configuration. Then again, the infinite upgrade path *is* the "audiophile way", isn't it! Thanks for suffering through my pontifications. Steve Z near Libby, MT Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 17:11:04 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Steve: We will never achieve zero extraneous vibrations at the stylus, although we must strive to get as close as possible. (I believe that the lossy approach comes the closest, but that's another arguement.) Since we can't completely eliminate extraneous vibrations, we must also strive to make them as benign as possible. Our old friend Ennemoser has theories on how to do that, and I will consider them carefully when I build my TT base. Ennemoser proposes that things that sound organic (like living bone) are the least intrusive to our ears and are the easiest for our brain to filter out when necessary. That would lead me to believe that the signatures of stainless steel or other bell-like substances (even when damped) are more intrusive and those materials should be avoided where possible. Cheers, Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Steve Zettel [SMTP:zettel@libby.org] > Sent: Thursday, March 23, 2000 1:56 PM > To: teres@aiko.com > Subject: Re: [teres] Teres-Bearing & Platter - Progress Report > ..... Seriously, though I don't subscribe to the notion that measurements tell it > all (else we'd all be listening to Japanese solid state amps that measure > flat from DC to light), in the case of a turntable we are dealing > primarily > with readily explainable and understandable physical phenomena when we > list > the criteria for function: unvarying speed, and zero extraneous vibrations > presented to the stylus/generator interface. What else am I forgetting? > ....... Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 17:35:27 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com At 01:55 PM 3/23/2000 -0700, Steve Zettel wrote: >on 3/23/00 08:27, Stanley Goudge at sgoudge@cisco.com wrote: > >> Thanks Steve for your open and honest remarks, sometimes I like to shake the >> bush a bit, so to speak, to find out what others are really thinking or >> desire, this way we can arrive at a general consensus maybe before Christmas. >> >You are welcome. If you want candor from me, all you need do is ask a >question. I am liable to speak my mind at any moment. > Your right of course Steve, but usually when I ask someone a question, I end up with more questions than answers. Bush shaking seems to produce answers that cover a wide array of topics, as I have noted here. And thanks BTW. >Regarding concensus by Christmas -- you *are* a starry-eyed >idealist, Stan! 8^) > What can I say? >> The many versions of Teres on Chris's web site look great, if fact they look >> so good that I'd love to see more design types. >> >Just wait a few minutes, I am sure you will see some. > >> Opens designs seem to me the current trend and I view this as a evolutionary >> process which started with the enclosed suspended subchassis (Linn) then onto >> the plintless designs (VPI, Basis) now the open designs (Spj, Simon York, >> ClearAudio) which seem to have achieved higher levels of performance. > >Somewhere out there, there may exist "the best" turntable design. >Stereophile and TAS seem to discover it every month. > I know what you mean, least the reviews are better than looking at pictures and who knows maybe the (some)reviewers can give incite to a design without the usual bias. It does give notice to a fast paced evolutionary process at a monthly speed. >> Plus >> they use less materials which should be more economical without performance >> loss, and done right we'll have performance gain at a lower cost, now that's >> evolutionary! > >Yeah, I just had a brainstorm -- this turntable design stuff isn't so hard. >We just take a big block of acrylic and remove everything that doesn't look >like a turntable! Viola! (not to be confused with the musical instrument of >the same name). > Sounds like a brainfar.. to me Steve... I know your kidding, so am I. >Seriously, though I don't subscribe to the notion that measurements tell it >all (else we'd all be listening to Japanese solid state amps that measure >flat from DC to light), in the case of a turntable we are dealing primarily >with readily explainable and understandable physical phenomena when we list >the criteria for function: unvarying speed, and zero extraneous vibrations >presented to the stylus/generator interface. What else am I forgetting? > I agree here. >That our understanding of the complex interactions of materials is imperfect >compounds our approach to solving the problem and may take us down some >wrong paths. But I submit the more we know about the experentially >verifiable properties of materials, the closer we get to making some correct >decisions. We obviously have eliminated large catagories of materials as >unsuitable for chassis construction: oatmeal, water above 0 degrees C, >horsefeathers. . . Absurd, perhaps, but though we didn't articulate the >process of analysis we haven't (yet) considered these materials because we >"know" that they would be less than satisfactory. > I agree here totally, oatmeal is not good. >Further, we have identified that we don't want relative motion, however >slight, between parts of our turntable, hence a very rigid and dimensionally >stable material and geometry is desirable. > Extremely desirable, I agree. >We don't want vibration, or energy that might manifest itself as vibration, >to be originated or propagated by any one part of our turntable to another >to the maximum extent possible. So, (I think) we want structurally rigid >material that is inherently dead or inert, and we want to dampen it as much >as possible. > I'm getting more flexible here only because I can't prove my theory, need a working model to be sure. Remember no material is inherently dead at all frequencies. >External vibrations haven't explicitly been discussed yet, other than some >mention in passing of sandboxes and air bladders. How best to accomplish >this (vibraplane in a vacuum vessel?) in an economical manner. One solution >is likely not to fit all, since we have project members living on concrete >slabs and on suspended frame floors. > Gentleman we have the technology, it enables man to leap from the highest buildings with out a parachute, unscathed. Its called bungee cord and according to my recent experiments with my trusty seismic generator. Suspended from bungee cord, I measured more than 10dB of noise immunity over any combo of sand and air bladders. This was measured on concrete slab using a 50lbs dumbbell as the noise source. More on this later. >For my part I have been cracking the old physics and engineering texts that >have been unopened on my bookshelf for too long and have been trying to >learn as much as I can about material properties, vibration and noise >control, acoustics, motors, power transmission, etc etc. > I remember building some speakers using Small's vented alignments, took me days to get all data and another to build it. It didn't sound good, so I had to tune it by hear. I think its best to make your best guess and tune it from there. But with todays computer programs, it's easy to start here. >So I've posed a bunch of questions and topics. Some of the tools that I >submit will help us make informed decisions have already been mentioned. >Manfred's analysis of the vibration of his motor, pod and mounting >arrangement was elegant in its simplicity: place the stylus of the very >signal generator we are worried about -- the cartridge -- on the bare >platter and run the motor with the belt off. Can we hear it? I need to do this, but I need another table to provide a load to the motor. > >There has been mention of using a surplus phono cartridge to do vibrational >analysis of various locations on the structure of the turntable. One project >member posted some values of transmissive index IIRC. This is great. We need >to collect this information and post it to the group, or at least the URLs >and sources of the literature so we all can become educated. I missed out here, where's the data? > >Our intuitive analysis of oatmeal and horsefeathers worked rather well in >eliminating these materials from consideration. However, intuition fails me >completely when trying to evaluate other materials much closer in properties >to what we may want -- Corian, acrylic, granite. Brass, aluminum, stainless >steel. MDF. Isodamp. Which is best for our application? Examination of the >materials and methods used by other endevours with similar concerns as ours >-- vibration control, speed control, structural integrity -- may answer some >of our questions. > Take your best guess and tune by ear. So one needs a tunable system, maybe like some I have proposed. >At present I don't know enough to pretend I have the answer. I have heard >some anecdotal evidence and read some interesting theories. I have also >waded through some questionable arguments for or against certain materials >and postulating some suspect physical explanations of the way things work. >The audio field is full of ex post facto justifications or explanations, but >I am thinking we can do better than that. > I agree, we all have pieces of the truth, they just need to put together correctly. >Personally, I fully expect to try several different chassis configurations, >perhaps as radically different as a heavily damped, welded steel inverted >dish-with-arms for tonearm mounts, to a MDF/Isodamp/Corian laminated slab >with acrylic discs for tonearm mounts. But I am hopeful that if we subject >our materials and designs to as rigorous an analysis as we are capable, we >might not have to go through endless iterations searching for the magic >combination. This process worked very well in arriving at a bearing design >and a platter configuration. > I agree, lets get radical. >Then again, the infinite upgrade path *is* the "audiophile way", isn't it! > Only if your a Bill Gates. >Thanks for suffering through my pontifications. > >Steve Z >near Libby, MT > I enjoyed Steve. Thanks, Stan Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 17:38:38 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; 'teres@aiko.com' Hey Ken is that the sound of someone beating a dead horse. If so, I think Ennemoser has some good theories. I like that word organic, reminds me of the sound of a Kouetsu rosewood cart. Stan At 04:12 PM 3/23/2000 -0700, Schei, Kenneth wrote: >Steve: > >We will never achieve zero extraneous vibrations at the stylus, although we >must strive to get as close as possible. (I believe that the lossy approach >comes the closest, but that's another arguement.) Since we can't completely >eliminate extraneous vibrations, we must also strive to make them as benign >as possible. Our old friend Ennemoser has theories on how to do that, and I >will consider them carefully when I build my TT base. Ennemoser proposes >that things that sound organic (like living bone) are the least intrusive to >our ears and are the easiest for our brain to filter out when necessary. >That would lead me to believe that the signatures of stainless steel or >other bell-like substances (even when damped) are more intrusive and those >materials should be avoided where possible. > >Cheers, Ken > >Ken Schei, P.E. >Project Engineer >Antarctic Support Associates >Email address: scheike@asa.org >Phone: 303-643-0163 > > >> -----Original Message----- >> From: Steve Zettel [SMTP:zettel@libby.org] >> Sent: Thursday, March 23, 2000 1:56 PM >> To: teres@aiko.com >> Subject: Re: [teres] Teres-Bearing & Platter - Progress Report >> > ..... Seriously, though I don't subscribe to the notion that >measurements tell it >> all (else we'd all be listening to Japanese solid state amps that measure >> flat from DC to light), in the case of a turntable we are dealing >> primarily >> with readily explainable and understandable physical phenomena when we >> list >> the criteria for function: unvarying speed, and zero extraneous vibrations >> presented to the stylus/generator interface. What else am I forgetting? >> ....... > Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 17:48:25 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/23/00 16:12, Schei, Kenneth at SCHEIKE@asa.org wrote: > Steve: > > We will never achieve zero extraneous vibrations at the stylus, although we > must strive to get as close as possible. (I believe that the lossy approach > comes the closest, but that's another arguement.) Since we can't completely > eliminate extraneous vibrations, we must also strive to make them as benign > as possible. Our old friend Ennemoser has theories on how to do that, and I > will consider them carefully when I build my TT base. Ennemoser proposes > that things that sound organic (like living bone) are the least intrusive to > our ears and are the easiest for our brain to filter out when necessary. > That would lead me to believe that the signatures of stainless steel or > other bell-like substances (even when damped) are more intrusive and those > materials should be avoided where possible. > > Cheers, Ken > Thanks, Ken I always value your input. I will have to familiarize myself with Ennemoser. Hmmm. . . a living bone turntable chassis. Now THAT is surely over the top! Steve Z Subject: Re: [teres] C37, Ennemoser, & Dead Horses Date: Thu, 23 Mar 2000 18:35:23 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com All, Stan jokingly asked if Ken was beating a dead horse about C37/Ennemoser. There was a whole dialog on the Joe List a month ago about Ennemoser / C37. Yes, this horse still has a pulse, but as soon as it's dead we can grind up its bones & mix it into some lacquer . Seriously, I have an open minded skepticism about all of this. Tom Danley had posted an interesting view on the matter. Usually, I don't like to cut 'n paste this sort of stuff but since this keeps surfacing, I think Tom makes some interesting points. A note to non-Joe Listers ... Tim Reese put together a utility for searching the digests, but this is not a real time index. Periodically, he sweeps through the accumulated posts and re-build the indices. As fate would have it, he already indexed the posts from mid-February. Tim's site is at: http://www.nmr.mgh.harvard.edu/~reese/joelist/ The web-based joe list archives are at: http://www.io.com/~ftp/mailing-lists/sound-digest/ Or ... the direct link to archive vol 2 #454 is: http://www.io.com/~ftp/mailing-lists/sound-digest/v02.n454 If you're interested in reading more of this discussion, start a few digests before #454. Look for "C37" in the topic ... a whole lot of stuff on what it is & how to make cheap versions of it (generally using violin lacquer). With apologies, here's Tom's controversial post ... ------------------------------- From: Thomas Danley Subject: Re: [JN] C37 Date: Sat, 19 Feb 2000 10:56:24 -0500 Source: Sound Digest Archive v02.n454 Allen Wright wrote: > Hi, > As Holger (who is the world distributor) doesn't seem to be answering these > items about C37, I'll say something. > > C37 is not a normal material, at least in it's intended operation. And it's > NOT a regular damping material. > > The concept is as follows - believe it or not - and while I use it and sell > it, I don't "believe" it myself so don't go giving me a hard time about it - > OK? > > Here goes: > > The human ear hearing system uses bones at body temp (98 deg F = 37 deg C > therefore the name C37). Bone is mostly carbon and has a specific resonance > spectrum at a given temperature. To avoid our hearing sounding like being > inside a huge carbon church bell all the time, the brain must have something > like a hardwired "carbon spectrum" filter that discounts these resonances. > > Enemoser's C37 is intended to MOVE the resonances of whatever it's applied to > to those of carbon at 37C, hence having them fall into the hearing systems > "filter notches"... Boy that sounds like a cool idea, a tiny flaw in it though is the indisputable fact that any objects pattern of resonance's are dictated by its physical shape and distribution of strength and mass, not a thin coating on the exterior. When a damping coating is applied it is adding a some mass (a reactive term) but damping comes from internal shear forces which act like a resistor lowering the Q. Resistive loss is damping. It is not possible (in the physical world) for a coating to "have preprogrammed" into it a resonant structure which will dominate the mechanical system it is applied to, think about this for a sec, this is absurd.. If one refers to the page on making fine finishes on Violins posted the other day for example, the description of how the finish effects the acoustics is totally consistent with acoustical reality while the description of C37 is not. > Does it work? To my ears YES! I have done several speaker cones with amazing > results, and did the bass cones in my speakers and no one who comes here can > believe that crappy project studio UREI 809 monitors can sound like they do. Cones are notorious for being the cheapest thing that "does the job" and it is very possible to apply a coating which helps to reduce the magnitude of resonance's. While not that familiar with building fine musical instruments, I am very familiar with building fine loudspeaker radiators and would say generally that it is considered to be "bad" when a loudspeaker produces more than the input signal asks for, even if it were a "desirable harmonic structure" like that proposed to exist in C-37. Recall that the "perfect" radiator has pure piston motion and so has NO other radiation other than that caused by the force supplied by the VC. Some loudspeakers like the JBL D series have a nonlinear motor and suspension deliberately in order to make them sound good as part of a music producer (guitar amp). In this case it is truly producer, part of the sound is caused by its property's. With a guitar it sounds good. On the other hand if one says the artist knew what there vision was and the "creation" process stopped when the recording was made, the musical systems job then becomes one of a RE-producer which requires faithful reproduction of the input signal only and NO more, not even a series of "special harmonics". Not a "PC" view on it I guess.. Tom Danley ------------- ----- Original Message ----- From: Stanley Goudge Sent: Thursday, March 23, 2000 4:35 PM Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Hey Ken is that the sound of someone beating a dead horse. If so, I think Ennemoser has some good theories. I like that word organic, reminds me of the sound of a Kouetsu rosewood cart. Stan At 04:12 PM 3/23/2000 -0700, Schei, Kenneth wrote: >Steve: > >We will never achieve zero extraneous vibrations at the stylus, although we >must strive to get as close as possible. (I believe that the lossy approach >comes the closest, but that's another arguement.) Since we can't completely >eliminate extraneous vibrations, we must also strive to make them as benign >as possible. Our old friend Ennemoser has theories on how to do that, and I >will consider them carefully when I build my TT base. Ennemoser proposes >that things that sound organic (like living bone) are the least intrusive to >our ears and are the easiest for our brain to filter out when necessary. >That would lead me to believe that the signatures of stainless steel or >other bell-like substances (even when damped) are more intrusive and those >materials should be avoided where possible. > >Cheers, Ken > >Ken Schei, P.E. __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 18:50:40 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com Hi Stan, Hi all > >> We don't want vibration, or energy that might manifest itself as vibration, >> to be originated or propagated by any one part of our turntable to another >> to the maximum extent possible. So, (I think) we want structurally rigid >> material that is inherently dead or inert, and we want to dampen it as much >> as possible. >> > I'm getting more flexible here only because I can't prove my theory, need > a working model to be sure. Remember no material is inherently dead at all > frequencies. Excellent. No energy storage or transmission! OK, skeletal is good. 8^) > >> External vibrations haven't explicitly been discussed yet, other than some >> mention in passing of sandboxes and air bladders. How best to accomplish >> this (vibraplane in a vacuum vessel?) in an economical manner. One solution >> is likely not to fit all, since we have project members living on concrete >> slabs and on suspended frame floors. >> > Gentleman we have the technology, it enables man to leap from the highest > buildings > with out a parachute, unscathed. Its called bungee cord and according to > my recent experiments with my trusty seismic generator. Suspended > from bungee cord, I measured more than 10dB of noise immunity over any combo > of sand and > air bladders. This was measured on concrete slab using a 50lbs dumbbell as the > noise source. More on this later. Alright! The sooner the better. For awhile BR (before remodelling) my Oracle rested on a sink cut-out of Corian, and the whole works was suspended by heavy surgical tubing from the uppermost shelf of one of those pipe and wire-rack storage shelf systems. The bottom shelf was mass-loaded with inert vinyl laminated with thin layers of heavy paper (LPs and sleeves). The next shelf had more mass loading with complex structures of steel, aluminum, copper, fiberglass and glass tubes (electronics components). The whole business was spiked through the carpet to the subfloor. I always felt it was the best isolation system I ever used. > >> For my part I have been cracking the old physics and engineering texts that >> have been unopened on my bookshelf for too long and have been trying to >> learn as much as I can about material properties, vibration and noise >> control, acoustics, motors, power transmission, etc etc. >> > I remember building some speakers using Small's vented alignments, took me > days to get all data and another to build it. It didn't sound good, so I had > to tune > it by hear. I think its best to make your best guess and tune it from there. > But with todays computer programs, it's easy to start here. I am not techno-weenie enough to believe that I can get the optimum solution from a book or a formula, without listening. I agree. I just want to get close and eliminate some false starts. But, it may turn out as it has in other phases of audio that the measurements we have of materials are not entirely relevant to what we hear. I am hoping that the transmissive index (I have got to go back through the recent messages and see if I am even using the right term here) and some other structural measures may prove to be good indicators. > > >> So I've posed a bunch of questions and topics. Some of the tools that I >> submit will help us make informed decisions have already been mentioned. >> Manfred's analysis of the vibration of his motor, pod and mounting >> arrangement was elegant in its simplicity: place the stylus of the very >> signal generator we are worried about -- the cartridge -- on the bare >> platter and run the motor with the belt off. Can we hear it? > > I need to do this, but I need another table to provide a load to the motor. > >> >> There has been mention of using a surplus phono cartridge to do vibrational >> analysis of various locations on the structure of the turntable. One project >> member posted some values of transmissive index IIRC. This is great. We need >> to collect this information and post it to the group, or at least the URLs >> and sources of the literature so we all can become educated. > > I missed out here, where's the data? This was in the nature of a posting to the Teres list by one of the members mentioning a figure of merit for several materials, such as MDF and Isodamp IIRC. I will look it up tonight. >> >> > Take your best guess and tune by ear. So one needs a tunable system, maybe > like some I have proposed. If what you come up with is close enough to fall within a range that shows improvement or disimprovement with the tuning process. Another tack would be to try two very different subchassis and see which comes closer to the ideal, then work from there. > > >> At present I don't know enough to pretend I have the answer. >> > I agree, we all have pieces of the truth, they just need to put together > correctly. You bet. I guess my bias is that whenever possible we have some sort of data to back up assertations and/or an explanation that conforms to the generally accepted laws of physics, if possible. Even personal experience is preferable to WAGs and hearsay. > >> > I agree, lets get radical. We are already there! When I tell my friends and coworkers that I listen to LPs in preference to CDs I get disbelieving looks. When I tell them we are building a world-class turntable to play these LPs, they start edging toward the door -- if they don't get belligerent and tell me how it would be impossible to do such a thing! > > >> Thanks for suffering through my pontifications. >> > I enjoyed Steve. Thank you. Lets hear more about the bungee cord suspension soon! Best regards, Steve Z Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 19:23:15 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > That would lead me to believe that the signatures > of stainless steel or > other bell-like substances (even when damped) are > more intrusive and those > materials should be avoided where possible. > > Cheers, Ken Got it. And now I understand the dirt suspension, the bamboo tonearm, and the anticipated rubber cartridge. Will you be posting design details? Sorry Ken, couldn't resist. Seriously, as this clearly points out, when trying to make headway with just words among strangers, it's all in one's subjective assessment and associated verbiage. Put just so, anything can sound outlandish if you intend it to...I'm still waiting for the missing engineering analysis of heavy, bendy materials bonded with flexible adhesives. A classis L/R assembly (yes, read Olson's "Elements of Acoustical Engineering") bound to take off at just the right (or wrong) frequency, - say, a couple hundred Hz - especially when acoustic feedback energy at *those* frequencies is probably a few thousand percent higher in impact than any internal energy. Not to mention reflecting nasty stuff trying to exit the arm right back to the cart for another go 'round. Latest TAS has a lengthy piece on the new $7k SOTA: A solid ~1" alloy plinth riddled with nickel-sized, polymer-filled holes - classic "damp a rigid chassis" thinking with obvious merit as a sink for the RIAA-intensive HF stuff put there by the cart/arm. And unable to be modulated by the heavy, mid-spectrum energy put into the air by the hi-fi itself. The design is called the best value in mega-tables on the market, especially for its' reputed ability to resolve all the fine stuff deep in the recording. Sounds like the arm/cart are really enjoying the ride on this, SOTA's radical departure from conventional wisdom. No more chipboard-and-goop chassis for them. Further, the latest S'Phile has Mikey lauding the Shun Mook'ed Oracle Delphi as the best sound at the show. Something about that rigid loop stuff really seems to work... Jon Lane Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 20:29:16 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/23/00 18:17, Jon Lane at jhlane@email.msn.com wrote: > I'm still waiting for the > missing engineering analysis of heavy, bendy materials > bonded with flexible adhesives. Still waiting for the missing engineering analysis of rigid, undamped materials vs. rigid, inert or inherently damped materials. > A classis L/R assembly Would you define L/R, please? > (yes, read Olson's "Elements of Acoustical Engineering") > bound to take off at just the right (or wrong) frequency, - > say, a couple hundred Hz - especially when acoustic feedback > energy at *those* frequencies is probably a few thousand > percent higher in impact than any internal energy. Not to > mention reflecting nasty stuff trying to exit the arm right > back to the cart for another go 'round. What does Olson say about acoustic feedback or transmitted energy at say, 10,000Hz and up? > > Latest TAS has a lengthy piece on the new $7k SOTA: A solid > ~1" alloy plinth riddled with nickel-sized, polymer-filled > holes - classic "damp a rigid chassis" thinking with obvious > merit as a sink for the RIAA-intensive HF stuff put there by > the cart/arm. And unable to be modulated by the heavy, > mid-spectrum energy put into the air by the hi-fi itself. > The design is called the best value in mega-tables on the > market, especially for its' reputed ability to resolve all > the fine stuff deep in the recording. Sounds like the > arm/cart are really enjoying the ride on this, SOTA's > radical departure from conventional wisdom. No more > chipboard-and-goop chassis for them. Imagine how good it would be with just as rigid a chassis made of some inherently inert material like carbon fiber, and nothing but air in those drilled holes (as Stan said, nothing to resonate or store or transmit energy). > > Further, the latest S'Phile has Mikey lauding the Shun > Mook'ed Oracle Delphi as the best sound at the show. > Something about that rigid loop stuff really seems to > work... Shun Mook, I always say. This is great anecdotal evidence but still no proof that rigid and transmissive and damped after the fact is somehow better than rigid and non-transmissive, damped or not. Now where did I leave those M'pingo discs? > > Jon Lane > Always interesting, Jon. Best regards, Steve Z Subject: Re: [teres] C37, Ennemoser, & Dead Horses Date: Thu, 23 Mar 2000 20:37:16 -0700 From: Nicholas McKinney, Nicholas McKinney To: teres@aiko.com > Enemoser's C37 is intended to MOVE the resonances of whatever it's applied to > to those of carbon at 37C, hence having them fall into the hearing systems > "filter notches"... (to which Tom said "poppycock") Toms description is pretty much dead on IMHO. I have played with all sorts of coatings, dampers, etc. and have yet to find a holy grail. While it might do something good, "moving" other object's resonances to a single pre-determined one (that of carbon) is pretty far fetched IMHO. Maybe if I apply enough if it to my car suspension, I can make the road noise sound better. Nick Subject: [teres] Its "internal damping factor", not "transmissivity index" (youdumby) Date: Thu, 23 Mar 2000 21:34:45 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com This is a requotation of the e-mail Daus sent introducing me to "internal damping factor". More values like this might give us a way to rank materials. Of course, rigidity (resistance to bending) and dimensional stability is just as important if not more so. > Hi everybody, I am finally back from spring break! > I too agree making the arm/platter coupling as rigid as possible. However, > bigger does not necessarily mean better. When finding the resonance > frequency of an object, you need to consider not the weight, but the mass > and dimensions. For example, you could have a stainless steel block of 12" > cubed that would have a higher resonance frequency than a stainless steel > rod of the dimensions of 12" diameter by 10 feet. But then again, we are > talking about the 1 mode of resonance. When you have damping like isodamp, > these modes become really insignificant in the design. When I get the time, > I plan on taking advantage of a design that has a primary resonance > frequency below the 15hz region. A factor that you would also like to take > advantage of for design is the type of material and its internal damping > factor. The higher the factor, the better. I was originally set on > Plexiglas (TF=.002) but found lead (TF=.015) a better performer. > Surprisingly, I found "wood waste material bonded with plastic" or MDF to > have an internal damping factor of (.005-.01). Add some isodamp material in > a sandwich, and you will increase that factor as well. With this approach, > you can use the material itself for the damping while nearly eliminating the > movement between the tonearm and the platter. > > Daus Could you cite some references when you get time, Daus? Thank you, Steve "Dumby" Z Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 21:52:00 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com Steve advised: > Still waiting for the missing engineering > analysis of rigid, undamped > materials vs. rigid, inert or inherently damped materials. Notice you snipped where I suggested "when trying to make headway with just words among strangers, it's all in one's subjective assessment and associated verbiage." Seems you proved the point. > > A classic L/R assembly > > Would you define L/R, please? Inductive/restive - pardon my informality. Suspending heavy, bendy masses between resilient adhesives, which has been suggested, if not in those exact words... > What does Olson say about acoustic feedback or > transmitted energy at say, > 10,000Hz and up? Probably more or less the same excellent treatment he offers on any other frequency, but that wasn't the entire context, was it? You omitted the fact that a heavy, bendy chassis is specifically susceptable to frequencies around those most like acoustic feedback, footfalls, and the like, and then strongly resists the elimination of same after the fact. But back to the question: What feedback, exactly? From where? At what level? > > Latest TAS has a lengthy piece on the new $7k > SOTA: A solid > > ~1" alloy plinth riddled with nickel-sized, > polymer-filled > > holes - classic "damp a rigid chassis" thinking > with obvious > > merit as a sink for the RIAA-intensive HF stuff > put there by > > the cart/arm. And unable to be modulated by the heavy, > > mid-spectrum energy put into the air by the > hi-fi itself. > > The design is called the best value in > mega-tables on the > > market, especially for its' reputed ability to > resolve all > > the fine stuff deep in the recording. Sounds like the > > arm/cart are really enjoying the ride on this, SOTA's > > radical departure from conventional wisdom. No more > > chipboard-and-goop chassis for them. > Imagine how good it would be with just as rigid a > chassis made of some > inherently inert material like carbon fiber, and > nothing but air in those > drilled holes (as Stan said, nothing to resonate > or store or transmit > energy). "Imagine"? "Nothing"? And you have an apparent issue with me opening discussion on a cause and effect based at least somewhat on logic, to put it conservatively? Hmmm. > > Further, the latest S'Phile has Mikey lauding the Shun > > Mook'ed Oracle Delphi as the best sound at the show. > > Something about that rigid loop stuff really seems to > > work... > Shun Mook, I always say. This is great anecdotal > evidence but still no proof > that rigid and transmissive and damped after the > fact is somehow better than > rigid and non-transmissive, damped or not. So you're saying we're no place. Perhaps the onus is equally on you then, dear friend. With a dearth of chipboard-n-glue 'tables on the scene, where's the evidence that a logical attempt to raise the fundamental resonance to a frequency it can be dealt with effectively is illogical or poorly advised? If 40 lbs of lumber and silicone, OTOH, is measured (and heard) hauling ass at 250 Hz, how you gonna stop it? And, is there any proof that arms don't respond favorably to impedance coupling to their chassis? Seems not to be the case if you investigate a bit. At least your notion of a stiff, carbon fiber chassis is a *significant* improvement...I'll give you that. BTW, are you going to try this? Sounds interesting. Jon Lane Subject: [Fwd: Re: [teres] Design Philosophy & Group Dynamics] Date: Thu, 23 Mar 2000 22:36:04 -0700 From: Chris Brady, Chris Brady To: tmackris@earthlink.net -------- Original Message -------- From: "Thom Mackris" Subject: Re: [teres] Design Philosophy & Group Dynamics To: All, Steve has eloquently described the design philosophy & phases of this project - that the bearing/platter design was the **only** phase where everyone should have had an intellectual/emotional investment since we needed to arrive at exactly *one* design for reasons of economy of scale. Subchassis? I would hope that there are as many different interpretations as there are builders. I truly thought that once the bearing and platter designs were solidified (current platter matierial dialog notwithstanding) we'd be into lightweight dialogs. BTW, Chris is working hard on the recent platter discoveries & will shortly be releasing information once he has it all consolidated. Without stealing his thunder, let me say that once again, Bryce was **WAY** ahead of us. Please don't interpret any of the following as a scolding. That is not my intent. I have no right to do that and, for the most part (99.99%), I'm proud of this group and to be a part of this effort as it has unfolded. A tiny minority of individuals has seen themselves as keepers of the flame of truth and the protectors of the great unwashed. Please realize that while we truly value your analysis, there is no need for you to protect us from others' thoughts. A healthy dialog will take care of this quite nicely. Part of the problem lies with the fact that some folks are either not *able* to or are not *inclined* to work in a group. Addidionally, some of us are new to listservers and newsgroups and the standards of etiquette that prevail. For these individuals, I think it's important for you to realize that we're all a big family here. We have far more *similarities* than we have differences. With every post, we bare our souls and thoughts in front of each other with the unwritten agreement that we are all involved in a common search for knowledge. When someone launches a subtle attack against another individual, the recipient of this agression feels violated and this trust is broken. This dynamic is a lot like learning to love and maintaining a long term personal relationship with a significant other. Let me close this rant by repeating that I *love* this group and 99% of the dialog which has occurred here. I feel truly priviliged the way this has unfolded. Now ... let's all have a group "hug" go out and design 40 or 50 *different* bases... then we'll *really* have stuff to compare ... at Arhus or nyNoise or the Colorado Audio Summit or VSAC ... Peace, Thom ----- Original Message ----- From: Steve Zettel Sent: Wednesday, March 22, 2000 8:40 PM Subject: Re: [teres] Teres-Bearing & Platter - Progress Report on 3/22/00 13:10, Stanley Goudge at sgoudge@cisco.com wrote: [snip] No need to sacrifice your ideas simply to achieve group concensus, Stan. There is no rush to come to a group subchassis design. Early on in the project it was decided that we had to ultimately achieve agreement on the parts that would be prohibitive for an individual to fabricate at home due to cost or complexity or need for highly precise measuring and milling equipment. Thus the platter, bearing well and spindle needed a unified design that could be contracted out, and economies of scale realized. The same reasoning applied to the motor/controller kit, coupled with the generosity of Manfred Huber volunteering his sophisticated design and support. However, I don't think we seriously expected to do one subchassis for all. This was to be the fertile area for customization and experimentation, where various philosophies could be applied and validated or discarded. Plenty of room for both the rigid and the lossy. [snip] I think it would be very interesting to be able to compare some of the finished products in a year or so, perhaps at Thom's Colorado Triode Summit. Steve Z __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 22:52:54 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com One more point, Steve. When you said, > > What does Olson say about acoustic feedback or > > transmitted energy at say, > > 10,000Hz and up? ...I failed to note that given the speed of sound through say, alloy being what it is, an approximately foot-and-a-half long aluminum loop between stylus and spindle is of insufficient length to develop even one full wavelength at 10kHz, making the notion of out-of-phase "feedback" at frequencies lower than that somewhat less exact. I once clumsily suggested that one might want "all energy to appear everyplace" thus canceling it. With an average 1kHz input by the cartridge, our 18" metal loop experiences less than a tenth of a wavelength at any one time; the phase effectively appearing everywhere instantaneously. Perhaps that's what I was trying to intuit. All of this must assume that energy once sunk into the enormous relative mass of a "conductive", *critically-damped* chassis will be so attenuated it won't be able to return to appreciably effect the input end of the machine. Transmission is utterly pointless without termination, as some would seem to overlook. Concerning the speed of sound in materials, perhaps our physicists could generously ruminate for us over the implications of V=sqrtB/p which includes B=bulk modulus of elasticity and p=density, a couple of intimately related variables...I think its time I retired again. Jon Lane Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 23:17:18 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/23/00 20:46, Jon Lane at jhlane@email.msn.com wrote: > Steve advised: > >> Still waiting for the missing engineering analysis of rigid, undamped >> materials vs. rigid, inert or inherently damped materials. >> > Notice you snipped where I suggested "when trying to make headway with just > words among strangers, it's all in one's subjective assessment and associated > verbiage." Seems you proved the point. > HUH? I meant just what I said, Jon. I am still waiting for the missing engineering analysis of rigid, undamped materials vs. rigid inert or inherently damped materials. No more, no less. >>> A classic L/R assembly >>> >> Would you define L/R, please? >> > Inductive/restive - pardon my informality. Suspending heavy, bendy masses > between resilient adhesives, which has been suggested, if not in those exact > words... > Jon, I am NOT a proponent of bendy masses, heavy or otherwise, or resilient adhesives. You are confusing me with someone else. I am all in favor of rigid, non-bending, dimensionally stable materials. Mass has nothing to do with it except as a secondary effect. What I want to find out is whether there is some advantage to be gained by using such rigid structures of materials that are less transmissive of energy and vibrations than metals, which depend on some external or internal damping to control resonances and ringing. >> What does Olson say about acoustic feedback or transmitted energy at say, >> 10,000Hz and up? >> > Probably more or less the same excellent treatment he offers on any other > frequency, but that wasn't the entire context, was it? You omitted the fact > that a heavy, bendy chassis is specifically susceptable to frequencies around > those most like acoustic feedback, footfalls, and the like, and then strongly > resists the elimination of same after the fact. > Once again Jon, please read what I have written carefully. I accept rigid, non-bending structures as a desireable given. I don't espouse glue and MDF as the be-all, end-all that you keep insisting is the other alternative to a rigid metallic chassis, or seem to construe as the sacred ox I am trying to protect. > But back to the question: What feedback, exactly? From where? At what > level? > Hmm, acoustic feedback would normally mean vibrations transmitted via the atmosphere, in a listening room, most probably from one's loudspeakers. Of course, an alternative definition could be taken to mean that feedback in the frequency range normally taken to be acoustic, ie 20-20,000kHz. Regardless, if you postulate that "heavy, bendy chassis is specifically susceptable to frequencies around those mose like acoustic feedback, footfalls and the like, and then strongly resists the elimination of the same after the fact." (by which I take you to mean, low frequencies), then does not it follow that these stiff, rigid and metallic structures would be susceptable to high frequency vibrations, whether acoustic (via air) or transmitted via structure? >>> Latest TAS has a lengthy piece on the new $7k SOTA: A solid ~1" alloy >>> plinth riddled with nickel-sized, polymer-filled holes - classic "damp a >>> rigid chassis" thinking with obvious merit as a sink for the RIAA-intensive >>> HF stuff put there by the cart/arm. And unable to be modulated by the >>> heavy, mid-spectrum energy put into the air by the hi-fi itself. The design >>> is called the best value in mega-tables on the market, especially for its' >>> reputed ability to resolve all the fine stuff deep in the recording. Sounds >>> like the arm/cart are really enjoying the ride on this, SOTA's radical >>> departure from conventional wisdom. No more chipboard-and-goop chassis for >>> them. >>> >> Imagine how good it would be with just as rigid a chassis made of some >> inherently inert material like carbon fiber, and nothing but air in those >> drilled holes (as Stan said, nothing to resonate or store or transmit >> energy). >> > "Imagine"? "Nothing"? And you have an apparent issue with me opening > discussion on a cause and effect based at least somewhat on logic, to put it > conservatively? Hmmm. "Imagine" because to the best of my knowledge there does not exist for example, a carbon-fiber or cast resin Sota to compare the aluminum to -- we must imagine it. "Nothing" as in "no matter except air". In a previous post Stan remarked that if we are worried about vibration transmission or retention, the no matter is the best matter. My hypothesis is that a rigid, inert material as chassis will intrude less on the musical information we are trying to retreive intact than a rigid, metallic structure. I have absolutely no issue with you or anyone opening a discussion based on logic. I do have a penchant for challenging assertations that do not seem to be adequately supported by physical evidence. That is all. Jon, please don't confuse an attack on an argument as an attack on yourself. I don't know you, but I respect your fervor and enthusiasm for a topic that interests me deeply, too. We are all trying to arrive at that most elusive of goals, "the Truth". > >>> Further, the latest S'Phile has Mikey lauding the Shun Mook'ed Oracle Delphi >>> as the best sound at the show. Something about that rigid loop stuff really >>> seems to work... This rigid loop stuff may indeed work very, very well. And I think it will work even better when it is implemented with inert material that does not support or transmit energy as readily as metallic substances do. >>> >> Shun Mook, I always say. This is great anecdotal evidence but still no proof >> that rigid and transmissive and damped after the fact is somehow better than >> rigid and non-transmissive, damped or not. >> > So you're saying we're no place. Not at all. I respect Mike Fremer a great deal. If he said the Mook'ed Delphi was the best sound at the show, I believe him. Fact filed away. But how does this prove that rigid and transmissive and damped after the fact is somehow better than rigid and non-transmissive? > Perhaps the onus is equally on you then, > dear friend. With a dearth of chipboard-n-glue 'tables on the scene, where's > the evidence that a logical attempt to raise the fundamental resonance to a > frequency it can be dealt with effectively is illogical or poorly advised? Why would I want a fundamental resonance ANYWHERE within the passband of my system, or anywhere where it might intermodulate with the information I AM trying to retrieve? I don't want it at 250HZ and I don't want it higher, either! How are we dealing with it effectively at this higher frequency? > If > 40 lbs of lumber and silicone, OTOH, is measured (and heard) hauling ass at > 250 Hz, how you gonna stop it? I am NOT espousing 40 lbs of lumber and silicone, Jon. May I return the favor and ask why you take such umbrage with me when I have not tried to assert the superiority of resilient, flexible structures for our application. May I ask though, the particulars of this measurement of ass-hauling at 250 Hz? Who performed these measurements? When? What was the sample population? What modes and frequencies? > > And, is there any proof that arms don't respond favorably to impedance > coupling to their chassis? Seems not to be the case if you investigate a bit. I would welcome any information based in fact comparing the results of rigid coupling vs. dampened coupling vs "impedance coupling" (and an explanation of what impedance coupling is). Seriously. I am not wedded to any particular method. Absent anything but assertations that one is superior over the other, I will go with my (however imperfect) understanding of physics. I am happy to be *proved* wrong, and thus avoid an expensive or time-consuming mistake. > > At least your notion of a stiff, carbon fiber chassis is a *significant* > improvement...I'll give you that. Why thank you, Jon. I thought it a significant improvement too. > BTW, are you going to try this? Sounds > interesting. Cost may prove to be a prohibitive factor for me, but I want to try as rigid and inherently inert material as I can possibly afford. One-off carbon fiber chassis' may be very pricy. Aluminum and steel is cheap enough that I can always risk proto-typing with metals if my theories don't pan out. As always, commentary is always invited. Agreement is not guaranteed. 8^) Steve Z Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Thu, 23 Mar 2000 23:30:40 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/23/00 21:48, Jon Lane at jhlane@email.msn.com wrote: > One more point, Steve. When you said, > >>> What does Olson say about acoustic feedback or >>> transmitted energy at say, >>> 10,000Hz and up? > > ....I failed to note that given the speed of sound through > say, alloy being what it is, an approximately > foot-and-a-half long aluminum loop between stylus and > spindle is of insufficient length to develop even one full > wavelength at 10kHz, making the notion of out-of-phase > "feedback" at frequencies lower than that somewhat less > exact. I once clumsily suggested that one might want "all > energy to appear everyplace" thus canceling it. With an > average 1kHz input by the cartridge, our 18" metal loop > experiences less than a tenth of a wavelength at any one > time; the phase effectively appearing everywhere > instantaneously. Perhaps that's what I was trying to > intuit. I'd ideally like no energy, in phase, or only a tenth of a wavelength out of phase, exciting my cartridge's generator, other than the modulations contained in the record's groove. > > All of this must assume that energy once sunk into the > enormous relative mass of a "conductive", > *critically-damped* chassis will be so attenuated it won't > be able to return to appreciably effect the input end of the > machine. Transmission is utterly pointless without > termination, as some would seem to overlook. So you posit a path from cartridge body to arm to armboard to chassis to large conductive chassis, which is critically damped and thus attenuated (dissapated) rather than returning to the arm? Could you explain what you mean by critically damped vs the more generic "damping" as I have been, perhaps inexactly, using it. Is this some kind of tuning? > > Concerning the speed of sound in materials, perhaps our > physicists could generously ruminate for us over the > implications of V=sqrtB/p which includes B=bulk modulus of > elasticity and p=density, a couple of intimately related > variables...I think its time I retired again. I hope by that you mean, go to bed. If you are going to pull the plug on Teres again, who besides Stanley will "beat the bushes" to see what falls out? 8^) Steve Z Subject: [teres] Teres-Bearing & Platter - New Info Date: Thu, 23 Mar 2000 23:34:16 -0700 From: Chris Brady, Chris Brady To: teres@aiko.com I have new information about our options for different platter materials. Cutting to the chase we have no other viable options. As usual Bryce had already fully explored our options. Bryce had already given 3" acrylic sheet full consideration including some price estimates. The price for the material 3" was roughly twice as much. But the real hitch for using the 3" material is cutting. Few suppliers have the capability to cut this thick of material and nobody local to Bryce can. Even though Bryce did not get an actual quote to cut the material he was certain that the cutting cost would be greater than the cost of the material. At this point using 3" acrylic is simply too expensive. There is an interesting possibility of having 3" circles cast rather than cutting them from sheet. This is also too expensive and uncertain to consider for this order, but it would be better than cutting from 3" sheet. For those with deep pockets and a desire for perfect cosmetics this would be a **possible** but expensive option for a future order. Bryce checked into using black acrylic and found that it was also very expensive. The problem is that colored acrylic is not commonly used and would be an expensive special order to get the quantity that we need. The price would be more than double and the lead time would be about 8 weeks. This is all a moot point since the platter materials have already been ordered and we didn't really have on option of changing the material order without paying some possibly stiff penalties. However, it is good to know that Bryce did his homework and I certainly would not change anything now even if we did have the option. Chris Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Fri, 24 Mar 2000 08:09:38 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com Steve asked: > HUH? You're a master at standing on both sides of the fence, Steve. Given your verbatim and immediate reversal of my words in that previous post, without introduction or qualification, I took your attitude not as an attack on myself, but as a defensive posture against something I must have said. Hence the repeat: We're all, to some degree, dealing with highly subjective assessments. Should be fairly clear. > I meant just what I said, Jon. I am still waiting > for the missing > engineering analysis of rigid, undamped materials > vs. rigid inert or > inherently damped materials. No more, no less. And I've been more than open in defining my remarks as open to formal analysis, which means *I* can't give you one, even though the theory obviously has its proponents and real-world examples. You should read again if you're still waiting for *that* white paper from me... > Jon, I am NOT a proponent of bendy masses, heavy > or otherwise, or resilient > adhesives. You are confusing me with someone > else. I am all in favor of > rigid, non-bending, dimensionally stable > materials. Mass has nothing to do > with it except as a secondary effect. What I want > to find out is whether > there is some advantage to be gained by using > such rigid structures of > materials that are less transmissive of energy > and vibrations than metals, > which depend on some external or internal damping > to control resonances and > ringing. And I'm a proponent of treating the arm as part of the system. They're made of...metal. > Once again Jon, please read what I have written > carefully. I accept rigid, > non-bending structures as a desireable given. I > don't espouse glue and MDF > as the be-all, end-all that you keep insisting is > the other alternative to a > rigid metallic chassis, or seem to construe as > the sacred ox I am trying to > protect. Then Steve, in "reading carefully" please respond to my claim that the *metal* arm is part of a system with the same enthusiasm you'd expect from my investigation of and replies to your missives. Thanks: We're on even ground now. > Hmm, acoustic feedback would normally mean > vibrations transmitted via the > atmosphere, in a listening room, most probably > from one's loudspeakers. Of > course, an alternative definition could be taken > to mean that feedback in > the frequency range normally taken to be > acoustic, ie 20-20,000kHz. > Regardless, if you postulate that "heavy, bendy > chassis is specifically > susceptable to frequencies around those mose like > acoustic feedback, > footfalls and the like, and then strongly resists > the elimination of the > same after the fact." (by which I take you to > mean, low frequencies), then > does not it follow that these stiff, rigid and > metallic structures would be > susceptable to high frequency vibrations, whether > acoustic (via air) or > transmitted via structure? *Only* within the context of, (1) the RIAA curve being present in the vinyl but not the speakers, and, (2) the vastly attenuated acoustic energy in the HF's relative to that the midbass. *My* tweeters move imperceptibly; my woofers, being 200 times the surface area, move a quarter inch. It you can modulate 10 lbs of damped alloy with *your* tweeters from across the room, your arm is already well into seizure. And at *that* level, the same would hold true for carbon, ceramic, what have you. Listen to your headshell. It's precisely *that* energy I'm more than a little concerned with. I've been saying that... > "Imagine" because to the best of my knowledge > there does not exist for > example, a carbon-fiber or cast resin Sota to > compare the aluminum to -- we > must imagine it. "Nothing" as in "no matter > except air". Not so fast, Steve. Your demands of others for formal analysis should mean your own are forthcoming. Imagine and nothing are unacceptable unless this forum is comfortable discussing these topics with subjective, informal dialog. > In a previous post > Stan remarked that if we are worried about > vibration transmission or > retention, the no matter is the best matter. Is your arm matter-less? > My hypothesis is that a rigid, > inert material as chassis will intrude less on > the musical information we > are trying to retreive intact than a rigid, > metallic structure. So you cause the arm to operate in isolation. Not a good idea if its a 707, Mayware, SME II, or the like, wouldn't you agree? And even if its an Ittok, are you certain it works best in isolation? If so, stand it up proud of the chassis on long bolts and listen to the result. > I have absolutely no issue with you or anyone > opening a discussion based on > logic. I do have a penchant for challenging > assertations that do not seem to > be adequately supported by physical evidence. That is all. Apply the same insight to your tonearm. The physical evidence suggests that it benefits from being vibrationally sunk. > Jon, please don't confuse an attack on an > argument as an attack on yourself. > I don't know you, but I respect your fervor and > enthusiasm for a topic that > interests me deeply, too. We are all trying to > arrive at that most elusive > of goals, "the Truth". Steve, your attitude was brusque, curt. It seems only when pursued, your motives - which I think are acceptable - come out. > Not at all. I respect Mike Fremer a great deal. > If he said the Mook'ed > Delphi was the best sound at the show, I believe > him. Fact filed away. But > how does this prove that rigid and transmissive > and damped after the fact is > somehow better than rigid and non-transmissive? Proof has yet to be a prerequisite for opinion expressed in this forum. > Why would I want a fundamental resonance ANYWHERE > within the passband of my > system, or anywhere where it might intermodulate > with the information I AM > trying to retrieve? Exactly. > I don't want it at 250HZ and > I don't want it higher, > either! How are we dealing with it effectively at > this higher frequency? That is the question. And given that it originates at your audibly modulated headshell where it is at many times the level it expresses in the chassis, what can we do to drain it, if anything? > I am NOT espousing 40 lbs of lumber and silicone. Good. Its the obvious first stop-off for the DIY builder, but not necessarily the most enlightened solution. > May I return the > favor and ask why you take such umbrage with me > when I have not tried to > assert the superiority of resilient, flexible > structures for our > application. The shortness of your reply. But I'll refrain from associating you with *that* design goal in the future. > May I ask though, the particulars of this > measurement of ass-hauling at 250 > Hz? Who performed these measurements? When? What > was the sample population? > What modes and frequencies? Steve, I'm just applying the same instinct you do when you question transmission/termination of stuff four octaves higher. There is no test result I can cite on ass-hauling. > I would welcome any information based in fact > comparing the results of rigid > coupling vs. dampened coupling vs "impedance > coupling" (and an explanation > of what impedance coupling is). Seriously. I am > not wedded to any particular > method. Absent anything but assertations that one > is superior over the > other, I will go with my (however imperfect) > understanding of physics. I am > happy to be *proved* wrong, and thus avoid an > expensive or time-consuming > mistake. Any mechanical engineers here able to take Steve and I up on our respective hypothesis? Jon Lane Subject: RE: [teres] Teres-Bearing & Platter - the not so great debate. Date: Fri, 24 Mar 2000 14:38:52 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com On Fri, 24 Mar 2000, Jon Lane wrote: > Steve asked: > > > HUH? > > You're a master at standing on both sides of the fence, > Steve. Sticks and stones, Jon. 8^) It is an easily managed posture that only requires one to fall off their high horse near a suitable fence. Given your verbatim and immediate reversal of my > words in that previous post, without introduction or > qualification, I took your attitude not as an attack on > myself, but as a defensive posture against something I must > have said. Hence the repeat: We're all, to some degree, > dealing with highly subjective assessments. Should be > fairly clear. Nope, not defensive here. Glad it wasn't perceived as an attack. It was meant in the spirit of vigorous debate. Don't read for hidden motives in what I write, Jon. I will state my motives very clearly: I would like to learn more about materials properties and their application to turntable construction. I like logical debate. > I meant just what I said, Jon. I am still waiting > > for the missing > > engineering analysis of rigid, undamped materials > > vs. rigid inert or > > inherently damped materials. No more, no less. > > And I've been more than open in defining my remarks as open > to formal analysis, which means *I* can't give you one, even > though the theory obviously has its proponents and > real-world examples. You should read again if you're still > waiting for *that* white paper from me... Oh, but I thought you stated you were still waiting for a formal analysis of a contrary position. I made the same request. I will look elsewhere, then. > > Jon, I am NOT a proponent of bendy masses, heavy > > or otherwise, or resilient > > adhesives. You are confusing me with someone > > else. I am all in favor of > > rigid, non-bending, dimensionally stable > > materials. Mass has nothing to do > > with it except as a secondary effect. What I want > > to find out is whether > > there is some advantage to be gained by using > > such rigid structures of > > materials that are less transmissive of energy > > and vibrations than metals, > > which depend on some external or internal damping > > to control resonances and > > ringing. > > And I'm a proponent of treating the arm as part of the > system. They're made of...metal. You shifted gears on me here. 8^) I thought we were talking chassis. . . But of course, that begs the response that the entire system needs to be considered as a whole. Stipulated. Most arms are made of metal, but there are some highly touted carbon fiber and even ceramic arms in production out there too. May I risk inferring then that you believe the entire structure should be constructed of the same material? > > > Once again Jon, please read what I have written > > carefully. I accept rigid, > > non-bending structures as a desireable given. I > > don't espouse glue and MDF > > as the be-all, end-all that you keep insisting is > > the other alternative to a > > rigid metallic chassis, or seem to construe as > > the sacred ox I am trying to > > protect. > > Then Steve, in "reading carefully" please respond to my > claim that the *metal* arm is part of a system with the same > enthusiasm you'd expect from my investigation of and replies > to your missives. Yes, Jon, the metal arm (or other material) is indeed part of the system. I guess that was unstated, but implicit in you previous post. Sorry I missed it. I was thinking "chassis". May I assume then, that you are postulating that arm material must determine chassis and armboard material? Or that they must match for optimum results? > Thanks: We're on even ground now. I somehow doubt this. . . 8^) > > Hmm, acoustic feedback would normally mean > > vibrations transmitted via the > > atmosphere, in a listening room, most probably > > from one's loudspeakers. Of > > course, an alternative definition could be taken > > to mean that feedback in > > the frequency range normally taken to be > > acoustic, ie 20-20,000kHz. > > Regardless, if you postulate that "heavy, bendy > > chassis is specifically > > susceptable to frequencies around those mose like > > acoustic feedback, > > footfalls and the like, and then strongly resists > > the elimination of the > > same after the fact." (by which I take you to > > mean, low frequencies), then > > does not it follow that these stiff, rigid and > > metallic structures would be > > susceptable to high frequency vibrations, whether > > acoustic (via air) or > > transmitted via structure? > > *Only* within the context of, (1) the RIAA curve being > present in the vinyl but not the speakers, and, (2) the > vastly attenuated acoustic energy in the HF's relative to > that the midbass. *My* tweeters move imperceptibly; my > woofers, being 200 times the surface area, move a quarter > inch. It you can modulate 10 lbs of damped alloy with > *your* tweeters from across the room, your arm is already > well into seizure. And at *that* level, the same would hold > true for carbon, ceramic, what have you. Thought experiment time. Imagine a wavetank with a large expanse of water uniformly one meter deep. Little ripples are being generated by a gentle breeze blowing across the surface of the water in high frequency, but very low energy puffs. At one end of the tank, the bottom slopes upward and the sides narrow in. What happens to the amplitude of those little ripples? I would submit a similar physical phenomenon is occuring from chassis to armboard to arm to cartridge body. I am not denying lower frequency energy is bad, I am saying that high frequency energy is too, so why utilize a material that by one of it's properties more readily transmits energy and requires additional damping (mass) if another material is available that meets all other dimensional stability requirements and is less transmissive? And thus either requires less damping, or lowers the energy content even lower for the same amount of damping? > > Listen to your headshell. It's precisely *that* energy I'm > more than a little concerned with. I've been saying that... I am sorry, I am dense. Which energy is it at the headshell? Energy originating at the cartridge, or energy travelling up the arm from the chassis? > > "Imagine" because to the best of my knowledge > > there does not exist for > > example, a carbon-fiber or cast resin Sota to > > compare the aluminum to -- we > > must imagine it. "Nothing" as in "no matter > > except air". > > Not so fast, Steve. Your demands of others for formal > analysis should mean your own are forthcoming. Imagine and > nothing are unacceptable unless this forum is comfortable > discussing these topics with subjective, informal dialog. Jon, I think we are both guilty then: I, of postulating that something might be better, without proof; you of asserting that metallic structures are superior to inert structures (let alone dismissing MDF out of hand as inferior) without proof. OK, you don't have it, so I will look for proof elsewhere. I am fine with informal and subjective (as opposed to observable) dialog. I have a problem with making that leap of faith and accepting it as fact. > > In a previous post > > Stan remarked that if we are worried about > > vibration transmission or > > retention, the no matter is the best matter. > > Is your arm matter-less? The context of that statement was a discussion of chassis. > > My hypothesis is that a rigid, > > inert material as chassis will intrude less on > > the musical information we > > are trying to retreive intact than a rigid, > > metallic structure. > > So you cause the arm to operate in isolation. Not a good > idea if its a 707, Mayware, SME II, or the like, wouldn't > you agree? And even if its an Ittok, are you certain it > works best in isolation? If so, stand it up proud of the > chassis on long bolts and listen to the result. Whoa, pardner! I think you skipped a few pages on me! Baby steps, please! How is an inert chassis and armboard causing the arm to try to work in isolation? Is this because you feel the arm and the armboard/chassis should all be the same material and work together as a monolithic unit? And that an interface that doesn't transmit energy must necessarily completely reflect it back? How about accepting the energy and dissipating it right there. This is my understanding of how certain classes of dampening material work. How do you propose to critically dampen your metal chassis. You can't be suggesting adding more (low frequency energy susceptable) mass? Certainly not resilient materials? Hmmm. Maybe carbon fiber arms on carbon fiber chassis are more desireable than metal arms on a carbon fiber chassis? Why would I want to use the arms from the list you provided? I think now I want to get one of those sexy carbon fiber jobs and retire my dowdy old Rega! > > I have absolutely no issue with you or anyone > > opening a discussion based on > > logic. I do have a penchant for challenging > > assertations that do not seem to > > be adequately supported by physical evidence. That is all. > > Apply the same insight to your tonearm. The physical > evidence suggests that it benefits from being vibrationally > sunk. Actually, I don't think so. 8^) I think I will apply my insight to my tonearm and hypothesize that the same benefits I postulate for an inert chassis hold true for an inert, non-resonant tonearm. > > Jon, please don't confuse an attack on an > > argument as an attack on yourself. > > I don't know you, but I respect your fervor and > > enthusiasm for a topic that > > interests me deeply, too. We are all trying to > > arrive at that most elusive > > of goals, "the Truth". > > Steve, your attitude was brusque, curt. It seems only when > pursued, your motives - which I think are acceptable - come > out. Well, I would have said blunt and to the point. But I apologize if I have ruffled your feathers. I am probably too thick-skinned and tend to run right over the sensibilities of others. I am sorry if you imputed some other motivation to my posts. I will try to be more precise and use more emoticons, if that would be helpful. > > Not at all. I respect Mike Fremer a great deal. > > If he said the Mook'ed > > Delphi was the best sound at the show, I believe > > him. Fact filed away. But > > how does this prove that rigid and transmissive > > and damped after the fact is > > somehow better than rigid and non-transmissive? > > Proof has yet to be a prerequisite for opinion expressed in > this forum. Agreed! > > > Why would I want a fundamental resonance ANYWHERE > > within the passband of my > > system, or anywhere where it might intermodulate > > with the information I AM > > trying to retrieve? > > Exactly. > > > I don't want it at 250HZ and > > I don't want it higher, > > either! How are we dealing with it effectively at > > this higher frequency? > > That is the question. And given that it originates at your > audibly modulated headshell where it is at many times the > level it expresses in the chassis, what can we do to drain > it, if anything? I will have to go home and listen to my headshell. Honestly don't recall hearing anything there with the stylus in the groove and the platter turning. Could be that my cartridge is well-damped and/or the headshell. Or that the headshell on the Rega, being the same piece as the arm is exceptionlly rigid and massive compared to other headshells. Or maybe I am deaf, in which case anyone still reading this on the Teres list should ignore what I have to say! 8^) > > I am NOT espousing 40 lbs of lumber and silicone. > > Good. Its the obvious first stop-off for the DIY builder, > but not necessarily the most enlightened solution. > > > May I return the > > favor and ask why you take such umbrage with me > > when I have not tried to > > assert the superiority of resilient, flexible > > structures for our > > application. > > The shortness of your reply. But I'll refrain from > associating you with *that* design goal in the future. Thank you. > > May I ask though, the particulars of this > > measurement of ass-hauling at 250 > > Hz? Who performed these measurements? When? What > > was the sample population? > > What modes and frequencies? > > Steve, I'm just applying the same instinct you do when you > question transmission/termination of stuff four octaves > higher. There is no test result I can cite on ass-hauling. OK, so we both are talking out of our ass.., er, making instinctual hypotheses to try and explain something I don't understand well. 8^) > > > I would welcome any information based in fact > > comparing the results of rigid > > coupling vs. dampened coupling vs "impedance > > coupling" (and an explanation > > of what impedance coupling is). Seriously. I am > > not wedded to any particular > > method. Absent anything but assertations that one > > is superior over the > > other, I will go with my (however imperfect) > > understanding of physics. I am > > happy to be *proved* wrong, and thus avoid an > > expensive or time-consuming > > mistake. > > Any mechanical engineers here able to take Steve and I up on > our respective hypothesis? Please! > Jon Lane Steve Z Subject: Re: [teres] Bases and Vibration Date: Fri, 24 Mar 2000 16:45:43 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Note the change in the subject line. I got tired of seeing "bearing & platter" in this ongoing discussion about bases and vibes. Part of the reason for this "heated" discussion is due to: (a) The fact that we don't have any bearings and platters on hand in order to test our theories. We therefor have all of this pent up energy which we are sublimating through our typing fingers (b) The fact that testing these theories is a lot more labor intensive than swapping a cap or changing from fixed bias to adjustable bias - we have to get out our saws and routers & this takes a whole lot more time & energy. The result is that we're all trying to "reason" a lot of this stuff out a priori. This is not a bad thing, and it has certainly modified my thinking on the subject. A couple of eye opening points that Jon made have me seriously considering the whole aluminum base concept. One of them has to do with the materials match at the interfaces (arm to base. bearing to base) & the inherrant reflection/acceptance of the vibrations. I'm not totally clear on this issue but it seems to me that if the area underneath the metal base performs a damping function, this might not be such a bad thing ... I'm still unclear on this and unprepared to take a stance. Another key point that Jon made relates to our good ol' friend the RIAA curve. Hardly anyone has commented on it and yet this seems to be one of the **keys** to Jon's argument. I'm really shocked that this hasn't received more air time. I can't remember the attenuation in the < 500 Hz band, but I believe it's in the area of 40 dB (someone correct me on the exact equalization). We're all talking about noble goals of eliminating *all* vibes but we know that this ain't gonna happen in this physical universe. Certainy we all agree that minimizing vibrations is a noble pursuit. So ... assuming (a) 40dB bass amplification by the RIAA circuit (b) that bass vibes are equally as bad as higher frequency vibes Then ... A base which resonates in the bass frequencies will have to be 40dB better than something which resonates in the upper frequency spectrum. If an equal level of bass vibration is *worse* than the equivalent level of upper frequency vibration, then the 40 dB number understates how much better the bass attenuation must be. Furthermore, we seem to be pretty good at designing brute force (mass) turntable stands which inherrently pass only low frequencies. This would seem to be a good argument for a base with a higher resonant frequency, since the combination of the low-pass filter formed by the stand and the high-pass filter formed by the base would be a good thing. The key question is - if we shift the vibes to a more benign frequency range, but in the process are less able to attenuate them, is this a bad thing or a good thing? If it's a good thing, how much can we get away with until it becomes a bad thing? In the spirit of fence sitting, my first iteration is looking like a hybrid aluminum/MDF structure, with the business end being aluminum (a block perhaps 1" thick) that connects the bearing and the tonearm. This will certainly be easy to build & should give me a good idea of where I want to procede with this design. Cheers, Thom __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Bases and Vibration Date: Fri, 24 Mar 2000 16:55:06 -0700 From: Thom Mackris, Thom Mackris To: Teres_List A follow-up to my RIAA equalization assumption ... with a 6dB / octave roll off starting at 500 Hz, the bass is - 6dB down at 250 Hz, 12 dB down at 125 Hz 18 dB down at 62.5 Hz 24 dB down at 31.25 Hz So - at 31.25 Hz, the RIAA will boost the bass by a factor of 128 !!! 2 ^ (24 / 3) = 2 ^ 6 = 128 Pretty compelling numbers, IMHO. Thom __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Bases and Vibration Date: Fri, 24 Mar 2000 18:37:06 -0700 From: Chris Brady, Chris Brady To: teres@aiko.com I also found that Jon's point compelling that the RIAA curve makes higher frequency resonance's more benign. Looking at the RIAA curve the signal is +8.22db at 200hz and -8.21db at 5khz a difference of 16.43db. So in theory if we had two resonances of equal amplitude, one at 200hz and one at 5khz the effect of the 200hz resonance would be almost 7 times stronger after it passed through the RIAA equalization. I suspect that higher frequency resonances are more audible. Even if this is the case the amount of attenuation in the RIAA curve would surely be more significant than the differences in audiblity. Resonances are obviously bad, but given a choice I would gladly trade the low frequency gremlins for the higher frequency variety. Chris > A follow-up to my RIAA equalization assumption ... > > with a 6dB / octave roll off starting at 500 Hz, the bass is - > > 6dB down at 250 Hz, > 12 dB down at 125 Hz > 18 dB down at 62.5 Hz > 24 dB down at 31.25 Hz > > So - at 31.25 Hz, the RIAA will boost the bass by a factor of 128 !!! 2 > ^ (24 / 3) = 2 ^ 6 = 128 > > Pretty compelling numbers, IMHO. > > Thom > > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com Subject: Re: [teres] Bases and Vibration Date: Fri, 24 Mar 2000 21:23:11 -0700 From: Doug Kelly, Doug Kelly To: teres@aiko.com > I also found that Jon's point compelling that the RIAA > curve makes higher frequency resonance's more benign. > > Looking at the RIAA curve the signal is +8.22db at 200hz > and -8.21db at 5khz a difference of 16.43db. So in theory > if we had two resonances of equal amplitude, one at 200hz > and one at 5khz the effect of the 200hz resonance would be > almost 7 times stronger after it passed through the RIAA > equalization. > Okay, I thought about this when Jon first brought it up, and the point I'm struggling with is: if we're talking _only_ about internally-generated vibrational energy ie groove/stylus induced vibration, won't it be the case that the excitation energy in the groove will have been cut by an amount exactly equivalent to the RIAA boost, thus making things come out in the wash? Now, I realize that we can't change the energy profile in the groove, but it still seems to me that if we accept the argument about RIAA boost changing the weighting of the 'badness' of a particular resonant frequency, we would also have to look at the 'typical' spectrum of excitation energy as well. In other words, if the excitation energy coming out of the groove is going up faster than the RIAA curve is going down, then pushing the resonance up is not a win. Now, the 'half power' point for music is often taken to be about 200 hz, but I don't really know how this is altered after running through the RIAA numbers. It would _seem_ to indicate that pushing it up is probably still better, but I'm not 100% sure. This will also be complicated in that higher frequency/energy modes will naturally decay into lower energy/frequency modes, if they exist. Blah. maybe we should all just get Edison cylinder players..... > I suspect that higher frequency resonances are more audible. > Even if this is the case the amount of attenuation in the RIAA > curve would surely be more significant than the differences > in audiblity. > > Resonances are obviously bad, but given a choice I would gladly > trade the low frequency gremlins for the higher frequency variety. > Well, probably only if we can push it high enough. Noise shaping in the digital world effectively does this - by adding a particular spectrum of dither, we decrease the noice in the mid band in exchange for much greater noise at the frequency extremes. Subjectively, this is a big win. I'm not sure that the materials we're talking about will allow us to push things much higher than the low midrange (big guess here, though), and I'd _really_ prefer to avoid coloration through the mids.... > Chris > > > A follow-up to my RIAA equalization assumption ... > > > > with a 6dB / octave roll off starting at 500 Hz, the bass is - > > > > 6dB down at 250 Hz, > > 12 dB down at 125 Hz > > 18 dB down at 62.5 Hz > > 24 dB down at 31.25 Hz > > > > So - at 31.25 Hz, the RIAA will boost the bass by a factor of 128 !!! 2 > > ^ (24 / 3) = 2 ^ 6 = 128 > > > > Pretty compelling numbers, IMHO. > > > > Thom > > > > __________________________________________________ > > Do You Yahoo!? > > Talk to your friends online with Yahoo! Messenger. > > http://im.yahoo.com Subject: Re: [teres] Bases and Vibration Date: Fri, 24 Mar 2000 21:56:17 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/24/00 20:36, Doug Kelly at kdouglas1@uswest.net wrote: > > Well, probably only if we can push it high enough. Noise shaping in the > digital world effectively does this - by adding a particular spectrum of > dither, we decrease the noice in the mid band in exchange for much > greater noise at the frequency extremes. Subjectively, this is a big > win. I'm not sure that the materials we're talking about will allow us > to push things much higher than the low midrange (big guess here, > though), and I'd _really_ prefer to avoid coloration through the > mids.... > Good things to think about, Jon, Thom, Chris, Doug. To me, colorations in the midrange seem very jarring, perhaps because so much of the musical information is located there that anything that doesn't sound natural really sounds colored to me. We have a lot to compare to in real life, or live music and perhaps that makes spotting artifical timber easier. But, brightness, hardness or harshness in the highs will drive me out of the room completely. It would be very interesting to see a vibration analysis of some turntable designs to see just what frequencies and amplitudes exist with differing construction. Steve Z Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 00:26:20 -0700 From: Ivan Anderson, Ivan Anderson To: teres@aiko.com Bases and Vibration it is then. Another 2c worth. In trying to minimise internally generated vibrational interference of the stylus and its ability to move only in response to the record groove, it is convenient to ignore externally generated vibration. Perhaps a few fundamentals should be reviewed. All vibration is the passage of energy in a medium in the form of transverse or longitudinal waves. When a wave encounters a boundary of any description it is either reflected, refracted, diffracted or transmitted (absorbed), or some combination of these events. The type of occurrence a wave undergoes at some boundary is dependent upon the impedance match of the materials forming that boundary, which is determined by the mass - elasticity relationship, or the mass, density, wave speed product. When the characteristic impedance of the material after the boundary matches the characteristic impedance of material in which the wave is travelling, the transmittance is complete. When a wave encounters a hard boundary (piece of string fixed to a wall) the wave is reflected 180 deg out of phase. When a wave meets a soft boundary (piece of string attached to a ring which is able to slide up and down a shaft) the wave is reflected in phase. All boundaries both transmit and reflect to some degree. If the wave travels from a high density to a low density medium then some of the wave is transmitted (accompanied by refraction) and some is reflected (in phase). If the wave travels from a low density to a high density medium, then the reflected portion is out of phase. Obviously the boundary between a dense medium and air has the wave reflected almost completely. A medium can only damp vibration which is not reflected, in other words, a medium can only damp (or dissipate) that vibration which is transmitted through it. Inert materials (a theoretical ideal) reflect the vibration they are not influenced by. Reflected complex vibration is modulated to show a lower frequency components of greater amplitude than the original. If we are to limit the influence of vibrational energy found in the arm, we must realise that it is manifest over a wide range and choices must be made as to where in the band and how wide we want our arm board or base impedance match to be. IMO it is wise to deal with the high frequencies first. Not only are these the frequencies that most affect the full extension of stylus travel and musical clarity but lower frequencies are still likely to be transmitted through the boundary and can be dealt with later in the chain. So, if this is the case, then we need an interface between the arm and armboard or base, which has a good broad impedance match especially at high frequencies. I would suggest that light and rigid meets this requirement, be it metallic or not. Of course if the material is the same as the arm, then a good impedance match can be assured, assuming that the mass and elasticity are of the same order. I feel that using a massive chassis of any description, as the first interface, is not a good idea, but each to his own... Having transmitted the vibration from the arm into the arm board / base, and limited the amount reflected back into the arm and cartridge, one can then go about dissipating it. This may involve damping materials, constrained layers or the inherent dissipating abilities of the medium. Presumably dealing with higher frequencies first and progressively the lower. I like the idea of metal tube as the first layer of the base. Not only does the top wall of the tube have a broad impedance match (depending on wall thickness, cross section, etc.) but the bottom side can be anchored to something more massive without affecting the transmittance/acceptance of the top too much and increasing the tube's inherent damping/dissipation properties. Other damping materials can also be applied as required. The main point?... A medium can only dissipate/damp the vibration that travels through it, and not that which it has reflected. Regards Ivan. ----- Original Message ----- From: "Thom Mackris" To: Sent: Saturday, 25 March 2000 10:50 Subject: Re: [teres] Bases and Vibration > Note the change in the subject line. I got tired of seeing "bearing & > platter" in this ongoing discussion about bases and vibes. Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 01:05:30 -0700 From: PEARL Cust Serv, PEARL Cust Serv To: teres@aiko.com Hello Ivan: > Bases and Vibration it is then. > > Another 2c worth. Never mind . . that was about 2 DOLLARS worth . . .thanks Best regards, Bill - PEARL, Inc. > In trying to minimise internally generated vibrational interference of > the stylus and its ability to move only in response to the record > groove, it is convenient to ignore externally generated vibration. > > Perhaps a few fundamentals should be reviewed. > > All vibration is the passage of energy in a medium in the form of > transverse or longitudinal waves. > > When a wave encounters a boundary of any description it is either > reflected, refracted, diffracted or transmitted (absorbed), or some > combination of these events. > > The type of occurrence a wave undergoes at some boundary is dependent > upon the impedance match of the materials forming that boundary, which > is determined by the mass - elasticity relationship, or the mass, > density, wave speed product. > > When the characteristic impedance of the material after the boundary > matches the characteristic impedance of material in which the wave is > travelling, the transmittance is complete. > > When a wave encounters a hard boundary (piece of string fixed to a > wall) the wave is reflected 180 deg out of phase. > > When a wave meets a soft boundary (piece of string attached to a ring > which is able to slide up and down a shaft) the wave is reflected in > phase. > > All boundaries both transmit and reflect to some degree. > > If the wave travels from a high density to a low density medium then > some of the wave is transmitted (accompanied by refraction) and some > is reflected (in phase). > > If the wave travels from a low density to a high density medium, then > the reflected portion is out of phase. > > Obviously the boundary between a dense medium and air has the wave > reflected almost completely. > > A medium can only damp vibration which is not reflected, in other > words, a medium can only damp (or dissipate) that vibration which is > transmitted through it. > > Inert materials (a theoretical ideal) reflect the vibration they are > not influenced by. > Reflected complex vibration is modulated to show a lower frequency > components of greater amplitude than the original. > > If we are to limit the influence of vibrational energy found in the > arm, we must realise that it is manifest over a wide range and choices > must be made as to where in the band and how wide we want our arm > board or base impedance match to be. > > IMO it is wise to deal with the high frequencies first. Not only are > these the frequencies that most affect the full extension of stylus > travel and musical clarity but lower frequencies are still likely to > be transmitted through the boundary and can be dealt with later in the > chain. > > So, if this is the case, then we need an interface between the arm and > armboard or base, which has a good broad impedance match especially at > high frequencies. I would suggest that light and rigid meets this > requirement, be it metallic or not. Of course if the material is the > same as the arm, then a good impedance match can be assured, assuming > that the mass and elasticity are of the same order. > > I feel that using a massive chassis of any description, as the first > interface, is not a good idea, but each to his own... > > Having transmitted the vibration from the arm into the arm board / > base, and limited the amount reflected back into the arm and > cartridge, one can then go about dissipating it. This may involve > damping materials, constrained layers or the inherent dissipating > abilities of the medium. Presumably dealing with higher frequencies > first and progressively the lower. > > I like the idea of metal tube as the first layer of the base. Not only > does the top wall of the tube have a broad impedance match (depending > on wall thickness, cross section, etc.) but the bottom side can be > anchored to something more massive without affecting the > transmittance/acceptance of the top too much and increasing the tube's > inherent damping/dissipation properties. Other damping materials can > also be applied as required. > > The main point?... A medium can only dissipate/damp the vibration that > travels through it, and not that which it has reflected. > > Regards > Ivan. > > Subject: RE: [teres] Teres-Bearing & Platter - Progress Report Date: Sat, 25 Mar 2000 01:30:58 -0700 From: Sellek, Grant (TSA), Sellek, Grant (TSA) To: 'teres@aiko.com'; 'Chris Brady ' Looks 100% fine by me. Pray proceed. BTW I think this matter is a dead issue... or should be. I apply my "does it make the boat go faster?" test. This term, I believe, comes from an America's Cup team, where if a team member starts grumbling about the colour of the sails or some such, they are asked "the question". *I* will take responsibility for the appearance of my TT, and I won't be trying to pass it on to Chris. I also object to any ideas of changing the specification, ie thicker acrylic sheet, grooved sides etc. Deadline's passed, get real. I particularly object to anyone sitting by the keyboard and insisting that their $200 cheque for a strictly DIY product has to buy, from DIY hobbyists, high-end appearance, never mind performance. We are dealing with generous fellow hobbyists here. Let's not abuse the privilege. Chris is being TOO kind. Right now if I were he or Thom, I would be starting to regret my offer as half the "community" starts exhibiting classic audio "upgrade path consumerism" in a COMPLETELY INAPPROPRIATE WAY, and what's worse, it's all about the colour of the sails. I also reckon there is a huge amount of exaggeration about "how much nicer" the 3" sheet would look. I can just see us all using our Teres in 6 months and thinking "*what* joint?". Grant PS who said the triple-layer platter won't look *better* to half the subscribers? I'm sure you don't want to hear what I think of the appearance of half the decks some of you admire so much to look at. Grant Sellek Adelaide, Australia grant.sellek@transport.sa.gov.au -----Original Message----- From: Chris Brady [mailto:cbrady@sgi.com] Sent: Tuesday, 21 March 2000 5:12 pm Subject: [teres] Teres-Bearing & Platter - Progress Report Subject: RE: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 05:07:16 -0700 From: Sellek, Grant (TSA), Sellek, Grant (TSA) To: 'teres@aiko.com' BUT.... Grant Sellek Adelaide, Australia grant.sellek@transport.sa.gov.au >-----Original Message----- >From: Thom Mackris [mailto:thom_mackris@yahoo.com] > >So ... assuming > >(a) 40dB bass amplification by the RIAA circuit >(b) that bass vibes are equally as bad as higher frequency vibes > >Then ... > >A base which resonates in the bass frequencies will have to be >40dB better >than something which resonates in the upper frequency >spectrum. If an equal >level of bass vibration is *worse* than the equivalent level of upper >frequency vibration, then the 40 dB number understates how >much better the bass attenuation must be. BUT... if the LP grooves at bass frequencies are of lesser amplitude, then the excitation of the system by the act of playing the LP will be that much less. So it seems to cancel out? But I agree with Thom's conclusion if one considers microphonics. Grant Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 09:40:05 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/24/00 23:11, Ivan Anderson at ivan@win.co.nz wrote: > In trying to minimise internally generated vibrational interference of > the stylus and its ability to move only in response to the record > groove, it is convenient to ignore externally generated vibration. OK. One source at a time. > > Perhaps a few fundamentals should be reviewed. Thank you, Ivan. I sincerely appreciate this. > > A medium can only damp vibration which is not reflected, in other > words, a medium can only damp (or dissipate) that vibration which is > transmitted through it. > > Inert materials (a theoretical ideal) reflect the vibration they are > not influenced by. > Reflected complex vibration is modulated to show a lower frequency > components of greater amplitude than the original. Interesting. > > If we are to limit the influence of vibrational energy found in the > arm, we must realise that it is manifest over a wide range and choices > must be made as to where in the band and how wide we want our arm > board or base impedance match to be. Not arguing here, and I realize we are taking one source of vibration at a time. However, it occurs to me -- and I don't want to lose the thought -- that perhaps we also need to know what the relative magnitude of these different sources of vibration are. Does the act of tracing the groove actually generate signficant energy that gets past the compliant suspension of the cartridge and and excite the body, headshell and arm? Ideally, the compliance of the cartridge and the effective mass of the arm are selected so that the tail is not wagging the dog. I know this is not an ideal world, and many cartridge manufacturers go to heroic (and often radically different approaches) to deal with vibrations and resonances within the structure of the cartridge and cantilever. Nonetheless, it would be good to know whether the chassis borne vibrations are more significant than the cartridge borne vibrations, and deal with the worst case first. > > IMO it is wise to deal with the high frequencies first. Not only are > these the frequencies that most affect the full extension of stylus > travel and musical clarity but lower frequencies are still likely to > be transmitted through the boundary and can be dealt with later in the > chain. Seems to make a case for dealing with the vibrations at the cartridge and headshell first, then the arm tube, then through the bearing(s) into the base, armboard, etc. At some point they are attenuated enough to be below the threshold of audibility. One would think. There is a very old trick of using a little Blu-tack or similar at the headshell or on the cartridge. . . Also tonearm wraps are favored by some. Of course, in a no-holds barred effort, maybe all of these should be applied! > > So, if this is the case, then we need an interface between the arm and > armboard or base, which has a good broad impedance match especially at > high frequencies. I would suggest that light and rigid meets this > requirement, be it metallic or not. Of course if the material is the > same as the arm, then a good impedance match can be assured, assuming > that the mass and elasticity are of the same order. So material matching is one key, but so is matching mass, and elasticity. > > I feel that using a massive chassis of any description, as the first > interface, is not a good idea, but each to his own... At what point to we go from being too massive to too light? If we for a minute assume an excellent decoupling of our table from structure borne vibrations (say, suspended by bungee cords), then the lighter our structure the more susceptible to excitation by acoustic energy. Of course, we have a built-in lower limit with a 3" thick acrylic platter coupled by a close tolerance bearing to our chassis! > > Having transmitted the vibration from the arm into the arm board / > base, and limited the amount reflected back into the arm and > cartridge, one can then go about dissipating it. This may involve > damping materials, constrained layers or the inherent dissipating > abilities of the medium. Presumably dealing with higher frequencies > first and progressively the lower. So, transmissive layers AND damping, perhaps constrained and/or externally applied. Like maybe a sandwich of two sheets of thin metal (Al or SS) constraining some Isodamp and perhaps a central core of styrofoam? The outer surface, except for mounting surfaces, covered with a thin layer of damping? Just throwing ideas. . . > > I like the idea of metal tube as the first layer of the base. Not only > does the top wall of the tube have a broad impedance match (depending > on wall thickness, cross section, etc.) but the bottom side can be > anchored to something more massive without affecting the > transmittance/acceptance of the top too much and increasing the tube's > inherent damping/dissipation properties. Other damping materials can > also be applied as required. When you say top wall of the tube, is this the open end of a tube oriented so that the open ends are facing up and down? A inverted bowl with top and bottom closed with flat plate, top drilled to accept the bearing bolt, filled with damping material. Maybe the entire external surface, except for the arm mounting interface, coated with plastisol or Isodamp. . . > > The main point?... A medium can only dissipate/damp the vibration that > travels through it, and not that which it has reflected. (Click, sound of light bulb coming on). Aha, now I see. > > Regards > Ivan. > Thank you, Ivan. Very succinctly put, in a logical succession of small steps that even I could understand. Jon is vindicated; I am dressed in sackcloth, heaping ashes upon my head! Seriously, I appreciate the clear explication in terms of physical principles that now sound familiar to me from high school physics classes. Steve Z Subject: RE: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 13:15:36 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > Does the act > of tracing the groove > actually generate signficant energy that gets > past the compliant suspension > of the cartridge and and excite the body, > headshell and arm? I've always thought all of that audible hash right at the playing end of the arm was a combination of record and arm-resonance... Have you heard it too? Jon Lane Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 16:17:46 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com Hi Everyone, I was exploring www.sorbothane.com and they had this really great sorbothane design guide program. I recommend that you check it out so that you can find out the right size and shape that you need the sorbothane to give you the right amount of isolation. For an approach that I will be using, four 1" thick by 1" diameter sorbothane pucks will provide about 97% isolation. Not bad! :) I think sorbothane isolation will be excellent for those of us that will be using the "granite block in a sandbox" approach. As for as my design, I have started to stray away from the "huge block" concept I originally thought was great. The added surface area would just act as a big magnet for sound induced resonances. I liked the Clearaudio and Chris' concept with the minimalist "four pod" design and long as everything is rigid and damped. I also looked at the Sounddown website and have been happy with their "spreadable" material for use in between MDF layers. About five layers of MDF with this stuff in the layers along with some exotic wood veneering will definately add to the "eye candy" effect I have been looking for. I also think it will be easy to construct using a vacuum bad and a bandsaw. Based on some calculations and experience, I think MDF is the way to go because of its high damping factor and mass. When you layer it, you get strength. Lead has the higher damping factor and if you could layer MDF and lead, that would be even better. I just wonder how friendly it is with bandsaws!! :) We all have great designs, I have a hard time believing that anyone will be "bad" considering that the platter and motor are such world class designs. Again, going against my orignal design, I think I will use a metal motor pod and is filled with sand/lead powder and silicon. If I wanted to do it correctly, I would used another MDF/goo intereface. But, a metal pod would look SOOOOOo cool!!! :) Another reason I am choosing this is because I have four Norsorex (unhappy) balls that I have been VERY happy with using uner my AR that would provide supperior isolation of the platter from the motor noise. If I have time, I will start up a webpage with my designs on CAD. I am anxiously awaiting the end of this semester in a month so that I may start putting some REAL work into this project!!! :) Good Luck Guys, Daus Subject: Re: [teres] Teres-Bearing & Platter - Progress Report Date: Sat, 25 Mar 2000 16:39:50 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com << At 04:12 PM 3/23/2000 -0700, Schei, Kenneth wrote: >Steve: > >We will never achieve zero extraneous vibrations at the stylus, although we >must strive to get as close as possible. (I believe that the lossy approach >comes the closest, but that's another arguement.) Since we can't completely >eliminate extraneous vibrations, we must also strive to make them as benign >as possible. Our old friend Ennemoser has theories on how to do that, and I >will consider them carefully when I build my TT base. Ennemoser proposes >that things that sound organic (like living bone) are the least intrusive to >our ears and are the easiest for our brain to filter out when necessary. >That would lead me to believe that the signatures of stainless steel or >other bell-like substances (even when damped) are more intrusive and those >materials should be avoided where possible. > >Cheers, Ken >> Ken, I'd like your input on possible compounds to use as a poured material. My plan for the base presently consists of arms forming an "X" pattern with the bearing mount at the intersection. The top of this "X" pattern will be at least 1/2 aluminum. Sides will be constructed of 1/16# aluminum that will be welded to the top plate. Then inverting the whole assembly will show the cavity of this "X" shaped structure that then will be poured with a "resin" material. I like the Ennemoser theories you have enlightened us with. Since aluminum is anti - Ennesmoser, that material must be countered with Ennesmoser materials. What about urethane mixed with graphite (expensive)? Or an epoxy resin poured on top of graphite. Carbon such as activated charcoal would be a possibility to reduce costs. Until Again, Gordon Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 17:07:49 -0700 From: christopher clark, christopher clark To: teres@aiko.com Howdy Folks, I've been reading the latest discussion about the constrained layer designs with great interest. Back in my audio retailing days, I once had a phone conversation with Jack Bybee, who uses constrained damping in some of his products. He contends that simply bonding several layers of differing materials together isn't really a constrained layer design (there's no constraint, only layers). He recommended to me that a good idea for a plinth would be to bond the layers together, then keep them under active compression with clamps or threaded bolts and nuts. Any thoughts? Chris Clark Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 17:32:00 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com The bolting idea makes a lot of sense, Chris. Gordon and I have discussed this and you might recall one of his posts on the subject. The gist of it is that by bolting, you have several options: (a) varying the clamping (bolts) pressure (b) the option of changing materials used in the various layers. Of course, given an infinite amount of time and $, we would experiment with numerous materials and adhesives :-)) Cheers, Thom ----- Original Message ----- From: christopher clark To: Sent: Saturday, March 25, 2000 4:07 PM Subject: Re: [teres] Bases and Vibration Howdy Folks, I've been reading the latest discussion about the constrained layer designs with great interest. Back in my audio retailing days, I once had a phone conversation with Jack Bybee, who uses constrained damping in some of his products. He contends that simply bonding several layers of differing materials together isn't really a constrained layer design (there's no constraint, only layers). He recommended to me that a good idea for a plinth would be to bond the layers together, then keep them under active compression with clamps or threaded bolts and nuts. Any thoughts? Chris Clark Subject: Re: [teres] Bases and Vibration Date: Sat, 25 Mar 2000 17:33:55 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com In a message dated 3/24/00 5:37:51 PM Mountain Standard Time, cbrady@sgi.com writes: << Looking at the RIAA curve the signal is +8.22db at 200hz and -8.21db at 5khz a difference of 16.43db. So in theory if we had two resonances of equal amplitude, one at 200hz and one at 5khz the effect of the 200hz resonance would be almost 7 times stronger after it passed through the RIAA equalization. >> True, but don't forget the ear is much more sensitive to upper midrange sounds say 500 - 5k. Also harmonics are more noticeable the higher they increase from the fundamental. Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 06:14:06 -0700 From: Ivan Anderson, Ivan Anderson To: teres@aiko.com Hi Steve, You replied in part: > > > > If we are to limit the influence of vibrational energy found in the > > arm, we must realise that it is manifest over a wide range and choices > > must be made as to where in the band and how wide we want our arm > > board or base impedance match to be. > > Not arguing here, and I realize we are taking one source of vibration at a > time. However, it occurs to me -- and I don't want to lose the thought -- > that perhaps we also need to know what the relative magnitude of these > different sources of vibration are. Does the act of tracing the groove > actually generate signficant energy that gets past the compliant suspension > of the cartridge and and excite the body, headshell and arm? Ideally, the > compliance of the cartridge and the effective mass of the arm are selected > so that the tail is not wagging the dog. I know this is not an ideal world, > and many cartridge manufacturers go to heroic (and often radically different > approaches) to deal with vibrations and resonances within the structure of > the cartridge and cantilever. Nonetheless, it would be good to know whether > the chassis borne vibrations are more significant than the cartridge borne > vibrations, and deal with the worst case first. Well yes, this type of information would be most helpful... but there is no doubt that the headshell and arm are excited to a significant degree, as witnessed by the change in reproduction character accompanying a change in arm board. However the isolation from external vibration requires an entirely different approach from that needed to absorb and dissipate internal vibration, and is altogether easier to achieve. I can find few studies into the dissipation of the frequency range we need to deal with, but there are any number dealing with the isolation of equipment. Isolation is best achieved (perhaps) by a two step approach, the use of mass and broadly innert material to reject the greatest band of frequency possible, and the damping of the narrow but vicious fundamental that these materials inevitibly have. > > > > IMO it is wise to deal with the high frequencies first. Not only are > > these the frequencies that most affect the full extension of stylus > > travel and musical clarity but lower frequencies are still likely to > > be transmitted through the boundary and can be dealt with later in the > > chain. > > Seems to make a case for dealing with the vibrations at the cartridge and > headshell first, then the arm tube, then through the bearing(s) into the > base, armboard, etc. At some point they are attenuated enough to be below > the threshold of audibility. One would think. > > There is a very old trick of using a little Blu-tack or similar at the > headshell or on the cartridge. . . > > Also tonearm wraps are favored by some. > > Of course, in a no-holds barred effort, maybe all of these should be > applied! You are right of course, and some experimentation is called for, however, the same considerations are required in this effort as they are in base / armboard design. I imagine that Blu-tack and arm wrap materials reflect high frequencies and alter the transmission properties of the arm, for better or worse, who knows. > > > > So, if this is the case, then we need an interface between the arm and > > armboard or base, which has a good broad impedance match especially at > > high frequencies. I would suggest that light and rigid meets this > > requirement, be it metallic or not. Of course if the material is the > > same as the arm, then a good impedance match can be assured, assuming > > that the mass and elasticity are of the same order. > > So material matching is one key, but so is matching mass, and elasticity. Matching impedence is the goal, of the suitable materials, judgements are made as to practicality, expense, appearance, smell, etc. > > > > I feel that using a massive chassis of any description, as the first > > interface, is not a good idea, but each to his own... > > At what point to we go from being too massive to too light? If we for a > minute assume an excellent decoupling of our table from structure borne > vibrations (say, suspended by bungee cords), then the lighter our structure > the more susceptible to excitation by acoustic energy. Of course, we have a > built-in lower limit with a 3" thick acrylic platter coupled by a close > tolerance bearing to our chassis! After the point where it is just right :-) Both too light and too massive cause the same problem, but we are talking interfaces here. The system might comprise of layers of increasingly dense materials, and further massive components aimed at isolation. > > Having transmitted the vibration from the arm into the arm board / > > base, and limited the amount reflected back into the arm and > > cartridge, one can then go about dissipating it. This may involve > > damping materials, constrained layers or the inherent dissipating > > abilities of the medium. Presumably dealing with higher frequencies > > first and progressively the lower. > > So, transmissive layers AND damping, perhaps constrained and/or externally > applied. Yes > Like maybe a sandwich of two sheets of thin metal (Al or SS) constraining > some Isodamp and perhaps a central core of styrofoam? The outer surface, > except for mounting surfaces, covered with a thin layer of damping? Maybe, but remember while a thin layer of metal may have a good impedence match in itself, as soon as you attach something else to it you change its properties. > Just throwing ideas. . . > > > > I like the idea of metal tube as the first layer of the base. Not only > > does the top wall of the tube have a broad impedance match (depending > > on wall thickness, cross section, etc.) but the bottom side can be > > anchored to something more massive without affecting the > > transmittance/acceptance of the top too much and increasing the tube's > > inherent damping/dissipation properties. Other damping materials can > > also be applied as required. > > When you say top wall of the tube, is this the open end of a tube oriented > so that the open ends are facing up and down? Sorry Steve, I was imagining a frame of mild steel rectangular tube (ERW tube which has raidiused corners) on its flat, say 50 x 20mm x 2mm wall thickness. I'm not saying this is what I will build, but I have had good results with variations on the theme. > A inverted bowl with top and bottom closed with flat plate, top drilled to > accept the bearing bolt, filled with damping material. Maybe the entire > external surface, except for the arm mounting interface, coated with > plastisol or Isodamp. . . I think the idea, others have had, of an inverted channel or upturned pan embeded in sand is well worth trying, perhaps an upturned heat sink shape embedded in sand. > > The main point?... A medium can only dissipate/damp the vibration that > > travels through it, and not that which it has reflected. > > (Click, sound of light bulb coming on). Aha, now I see. A small but not insignificant point ;-) > > Regards > > Ivan. > > > Thank you, Ivan. Very succinctly put, in a logical succession of small steps > that even I could understand. > > Jon is vindicated; I am dressed in sackcloth, heaping ashes upon my head! We can stick you in the stocks if you think that will help. Some of Jon's ideas suffer an impedence mis-match also. The fields of mechanical vibration and acoustics are complex and not completely mapped as yet, in deed, if a series of tests corelate with the theory there seems to be much back slapping and wiping of brow, if what I have been reading lately is any indication. > Seriously, I appreciate the clear explication in terms of physical > principles that now sound familiar to me from high school physics classes. > > Steve Z Glad to be of some use! Ivan. Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 10:53:21 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Sat, 25 Mar 2000, christopher clark wrote: > Back in my audio retailing days, I once had a phone conversation with > Jack Bybee, who uses constrained damping in some of his products. He > contends that simply bonding several layers of differing materials > together isn't really a constrained layer design (there's no > constraint, only layers). He recommended to me that a good idea for a > plinth would be to bond the layers together, then keep them under > active compression with clamps or threaded bolts and nuts. > > Any thoughts? Agreed. The plinth sandwich I use is Corian/Dynamat/Lead/Aluminum. There are threaded holes in the 3/8" aluminum and hexhead bolts ar fitted through the Corian from the top. The bonding was done under weight and the bolts are available now to adjust tension. Kal Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 12:44:10 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/26/00 04:58, Ivan Anderson at ivan@win.co.nz wrote: > Hi Steve, > Hi Ivan, > Ivan wrote, about my questions concering the relative strength of chassis vs > arm vibrations: > > Well yes, this type of information would be most helpful... but there is no > doubt that the headshell and arm are excited to a significant degree, as > witnessed by the change in reproduction character accompanying a change in arm > board. > I am going to do an experiment to check that out, changing my existing acrylic armboard to aluminum. My Oracle has been a test bed of sorts for some of our early Teres questions, might as well continue. > However the isolation from external vibration requires an entirely different > approach from that needed to absorb and dissipate internal vibration, and is > altogether easier to achieve. I can find few studies into the dissipation of > the frequency range we need to deal with, but there are any number dealing > with the isolation of equipment. > Yes indeed. Visiting the Soundown and EAR sites, as well as any number addressing resilient mounts proved that to be the case. > Isolation is best achieved (perhaps) by a two step approach, the use of mass > and broadly innert material to reject the greatest band of frequency possible, > and the damping of the narrow but vicious fundamental that these materials > inevitibly have. > The other tack would be to accept a greater range of frequencies, but hopefully at a lower (near or below audibility) energy level. Damping could be applied here, too, I suppose. >>> Ivan had also written earlier: >>> >>> IMO it is wise to deal with the high frequencies first. Not only are these >>> the frequencies that most affect the full extension of stylus travel and >>> musical clarity but lower frequencies are still likely to be transmitted >>> through the boundary and can be dealt with later in the chain. >> Steve Z postulated in reply: >> Seems to make a case for dealing with the vibrations at the cartridge and >> headshell first, then the arm tube, then through the bearing(s) into the >> base, armboard, etc. At some point they are attenuated enough to be below the >> threshold of audibility. One would think. >> >> There is a very old trick of using a little Blu-tack or similar at the >> headshell or on the cartridge. . . >> >> Also tonearm wraps are favored by some. >> >> Of course, in a no-holds barred effort, maybe all of these should be applied! >> >Ivan returned: > You are right of course, and some experimentation is called for, however, the > same considerations are required in this effort as they are in base / armboard > design. I imagine that Blu-tack and arm wrap materials reflect high > frequencies and alter the transmission properties of the arm, for better or > worse, who knows. Certainly, Blu-Tack between the cartridge and headshell might reflect back energy, but some appreciable amount of energy must be getting absorbed and disipated at/in the lossier substance. Ditto armwrap on the surface of the arm. After all, this is how extensional damping works, and it has been proven to work in industrial and military applications. Besides, energy is already being reflected back by the material-to-air interface already. But I agree, besides lowering the energy content at some range of frequencies of the arm or headshell or whatever, no doubt adding the damping alters the transmission characteristics of the new damping/base material system. It doesn't alter the characteristics of the base material though. Aluminum is still aluminum, acrylic still acrylic. And I also agree, more experimentation is needed. I plan to also check out what happens when I add an arm wrap to my Rega RB-300. One correspondent on the Phonogram list reports great success with it. > snip > >> Steve (in the nature of a question, not statement of fact): >> So material matching is one key, but so is matching mass, and elasticity. > Ivan: > Matching impedence is the goal, of the suitable materials, judgements are made > as to practicality, expense, appearance, smell, etc. > >>Steve: >> At what point to we go from being too massive to too light? If we for a >> minute assume an excellent decoupling of our table from structure borne >> vibrations (say, suspended by bungee cords), then the lighter our structure >> the more susceptible to excitation by acoustic energy. Of course, we have a >> built-in lower limit with a 3" thick acrylic platter coupled by a close >> tolerance bearing to our chassis! >> > After the point where it is just right :-) Both too light and too massive > cause the same problem, but we are talking interfaces here. The system might > comprise of layers of increasingly dense materials, and further massive > components aimed at isolation. This would seem to say that one I idea I had, for a sandwiched construction of aluminum plate outside, then Isodamp or Dynamat, and a central core of styrofoam is not as good an idea as going from outer layers of aluminum to denser and denser layers, ending up with a central core of lead? > snip > >>Steve: >> Like maybe a sandwich of two sheets of thin metal (Al or SS) constraining >> some Isodamp and perhaps a central core of styrofoam? The outer surface, >> except for mounting surfaces, covered with a thin layer of damping? >> > Maybe, but remember while a thin layer of metal may have a good impedence > match in itself, as soon as you attach something else to it you change its > properties. If we don't place the damping between the two aluminum (for instance) pieces to be joined then at the interface we have as close a match as possible. I am not ignoring that you also mentioned matching mass and elasticity of the two materials, but I don't think we are going to practically have a chassis/armboard of the same mass as the arm/headshell. And we would never be able to apply damping in any case. All I see as an alternative is as gentle an impedance transformation from one part to the other as we go from component part to another. > snip > >>> I like the idea of metal tube as the first layer of the base. Not only does >>> the top wall of the tube have a broad impedance match (depending on wall >>> thickness, cross section, etc.) but the bottom side can be anchored to >>> something more massive without affecting the transmittance/acceptance of the >>> top too much and increasing the tube's inherent damping/dissipation >>> properties. Other damping materials can also be applied as required. >>> >> When you say top wall of the tube, is this the open end of a tube oriented so >> that the open ends are facing up and down? >> > Sorry Steve, I was imagining a frame of mild steel rectangular tube (ERW tube > which has raidiused corners) on its flat, say 50 x 20mm x 2mm wall thickness. > I'm not saying this is what I will build, but I have had good results with > variations on the theme. Oh. Well, we have lots of odd lengths of this and larger in the scrap pile at work. > snip >> > I think the idea, others have had, of an inverted channel or upturned pan > embeded in sand is well worth trying, perhaps an upturned heat sink shape > embedded in sand. We also have some lengths of large, heavy aluminum channel (8" across and 2" flanges) that would seem to fit this description. > >>> The main point?... A medium can only dissipate/damp the vibration that >>> travels through it, and not that which it has reflected. >>> Well, it can still travel through it even if extensional damping is applied to the surface, though I agree, the application of damping changes the system as a whole. Bottom line, lots of things to play with. Thanks again, Ivan Steve Z near Libby, MT Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 12:58:53 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/25/00 12:05, Jon Lane at jhlane@email.msn.com wrote: > > I've always thought all of that audible hash right at the > playing end of the arm was a combination of record and > arm-resonance... Have you heard it too? > > Jon Lane I have done a little listening now with my ear near the cartridge and I do hear little whispery voices singing and ghostly music. . . imaging is very poor and the soundstage is quite narrow with no depth at all. Timbral and tonal balance is very distorted. 8^) Seriously, there certainly is something audible at the vinyl/stylus/cartridge interface. Now whether that is accentuated by a high impedance interface at the arm/armboard junction is a good question. Easy enough to experiment with on my table (though I dread re-aligning my arm/cartridge one more time!): I will fab up an armboard of aluminum and replace the Delphi MK II acrylic armboard and see what happens. My understanding is that Oracle went to an aluminum armboard in a later version of the Delphi also. Must be some reason, eh? I am also planning to try some arm damping if I can track down the Warren Gehl armwrap from a vendor willing to mail order to Montana (it's not like I am in *anybody's* retail territory). No Blu-Tack at the cartridge arm interface for now, as I don't want anything resiliant interfering with a rigid interface between cartridge and arm -- though I do note with interest that part of the package that came with my Clearaudio was a thin lead wafer that was meant to be inserted between cartridge and arm in the event one's arm needed to see a bit more massy cartridge. Best regards, Steve Z Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 13:18:36 -0700 From: Roscoe Primrose, Roscoe Primrose To: teres@aiko.com Steve Zettel wrote: > > on 3/25/00 12:05, Jon Lane at jhlane@email.msn.com wrote: > > > > I've always thought all of that audible hash right at the > > playing end of the arm was a combination of record and > > arm-resonance... Have you heard it too? > > > > Jon Lane > > I have done a little listening now with my ear near the cartridge and I do > hear little whispery voices singing and ghostly music. . . imaging is very > poor and the soundstage is quite narrow with no depth at all. Timbral and > tonal balance is very distorted. 8^) > There's always going to be some sound, think about it, you've got a stylus, moving about in the air, how could it possible NOT make noise? Peace -- Roscoe Primrose -- mailto:roscoe@aiko.com -- http://www.aiko.com/roscoe -- "Once in a while you get shown the light In the strangest of places if you look at it right." Robert Hunter Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 15:31:45 -0700 From: PEARL Cust Serv, PEARL Cust Serv To: teres@aiko.com Roscoe Primrose roscoe@aiko.com wrote > Steve Zettel wrote: >> >> on 3/25/00 12:05, Jon Lane at jhlane@email.msn.com wrote: >> > >> > I've always thought all of that audible hash right at the >> > playing end of the arm was a combination of record and >> > arm-resonance... Have you heard it too? >> > >> > Jon Lane >> >> I have done a little listening now with my ear near the cartridge and I do >> hear little whispery voices singing and ghostly music. . . imaging is very >> poor and the soundstage is quite narrow with no depth at all. Timbral and >> tonal balance is very distorted. 8^) >> > > There's always going to be some sound, think about it, you've got a > stylus, moving about in the air, how could it possible NOT make noise? > > Peace > -- > Roscoe Primrose =============================== Hi Roscoe, All: If you think carefully about it, you will soon realize: I) the stylus/cantilever is FAR too small to generate even tiny sound pressures at midband frequencies. Any acoustic output it might generate simply "short circuits" around its miniscule dimensions in exactly the same way that a dipole increasingly self-cancels with decreasing frequency . . . ii) the far more likely sound source is the due to the waves propagating across the surface of the vinyl; these being initiated thru the fact of the grooves' deflections while containing the many-G forces of acceleration sustained by the stylus/cantilever as the stylus traces the grooves. Because of their distributed nature, these waves will radiate rather effectively - and somewhat omni-directionally - into the surrounding environment . . . Best regards, Bill - PEARL, Inc. Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 19:59:26 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com Hi, Bill > > Hi Roscoe, All: > If you think carefully about it, you will soon realize: > > I) the stylus/cantilever is FAR too small to generate even tiny sound > pressures at midband frequencies. Any acoustic output it might generate > simply "short circuits" around its miniscule dimensions in exactly the same > way that a dipole increasingly self-cancels with decreasing frequency . . . > > ii) the far more likely sound source is the due to the waves propagating > across the surface of the vinyl; these being initiated thru the fact of the > grooves' deflections while containing the many-G forces of acceleration > sustained by the stylus/cantilever as the stylus traces the grooves. > Because of their distributed nature, these waves will radiate rather > effectively - and somewhat omni-directionally - into the surrounding > environment . . . > Very interesting comments. I think you are on to something here, at least with my present setup. I did a quick and dirty experiment just now with my turntable: I left the amps off and played a record first with the record clamp off, then with it on and tightened down. BIG difference in perceived volume of sound from the area of the stylus. The sound stage opened up dramatically and there was a vastly improved delineation of inner detail a harmonic texture, and the highs became more extended and airy. . . 8^) Strike that last! With the clamp on and tightened down, the amount of sound was less, with the clamp off, it increased. I was able to keep lowering the perceived output by tightening the clamp until I had it reefed down as much as I dared. Thanks for bringing this up. It will be interesting to experiment with some headshell damping and armwrap as well. Steve Subject: Re: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 21:15:15 -0700 From: PEARL Cust Serv, PEARL Cust Serv To: teres@aiko.com Steve Zettel zettel@libby.org wrote: > Hi, Bill >> >> Hi Roscoe, All: >> If you think carefully about it, you will soon realize: >> >> I) the stylus/cantilever is FAR too small to generate even tiny sound >> pressures at midband frequencies. Any acoustic output it might generate >> simply "short circuits" around its miniscule dimensions in exactly the same >> way that a dipole increasingly self-cancels with decreasing frequency . . . >> >> ii) the far more likely sound source is the due to the waves propagating >> across the surface of the vinyl; these being initiated thru the fact of the >> grooves' deflections while containing the many-G forces of acceleration >> sustained by the stylus/cantilever as the stylus traces the grooves. >> Because of their distributed nature, these waves will radiate rather >> effectively - and somewhat omni-directionally - into the surrounding >> environment . . . >> > Very interesting comments. I think you are on to something here, at least > with my present setup. I did a quick and dirty experiment just now with my > turntable: I left the amps off and played a record first with the record > clamp off, then with it on and tightened down. BIG difference in perceived > volume of sound from the area of the stylus. > > The sound stage opened up dramatically and there was a vastly improved > delineation of inner detail a harmonic texture, and the highs became more > extended and airy. . . > > Strike that last! With the clamp on and tightened down, the amount of sound > was less, with the clamp off, it increased. I was able to keep lowering the > perceived output by tightening the clamp until I had it reefed down as much > as I dared. > > Thanks for bringing this up. > > It will be interesting to experiment with some headshell damping and armwrap > as well. > > Steve +++++++++++++++++++++++ Hi: This is old hat really . . . . vacuum hold-down T/Ts exist in the first place to deal with THIS issue probably more than record warp. Anybody have any skookum ideas on how to incorporate this into a subsequent Teres model? Best regards, Bill - PEARL, Inc. Subject: RE: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 22:29:30 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > > I have done a little listening now with my ear > near the cartridge and I do > > hear little whispery voices singing and ghostly > music. . . imaging is very > > poor and the soundstage is quite narrow with no > depth at all. Timbral and > > tonal balance is very distorted. 8^) > > > > There's always going to be some sound, think > about it, you've got a > stylus, moving about in the air, how could it > possible NOT make noise? Nope, cheap 'shells sound much louder - its structural. Jon Lane Subject: RE: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 22:29:41 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > I have done a little listening now with my ear > near the cartridge and I do > hear little whispery voices singing and ghostly > music. . . imaging is very > poor and the soundstage is quite narrow with no > depth at all. Timbral and > tonal balance is very distorted. 8^) Tends to illustrate the spectrum is centered right where the ear is most sensitive... > Seriously, there certainly is something audible at the > vinyl/stylus/cartridge interface. Now whether > that is accentuated by a high > impedance interface at the arm/armboard junction > is a good question. Easy > enough to experiment with on my table (though I > dread re-aligning my > arm/cartridge one more time!): I will fab up an > armboard of aluminum and > replace the Delphi MK II acrylic armboard and see > what happens. My > understanding is that Oracle went to an aluminum > armboard in a later version > of the Delphi also. Must be some reason, eh? I used to make aluminum boards for the AR that replaces the shoddy fiberboard ones and better coupled the arm to the alloy subchassis. The improvement in small detail and image focus was pronounced even if the weight of these boards tended to make the chassis impossible to balance. The Oracle, it could be argued, is a better design than as-shipped given the plastic armboard. Jon Lane Subject: RE: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 22:31:24 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com Steve experimented with clamping the record and commented, > The sound stage opened up dramatically and there > was a vastly improved > delineation of inner detail a harmonic texture, > and the highs became more > extended and airy. . . 8^) Interesting, this is the *exact* terminology I'd use to describe tight mechanical bonding between arm and chassis too...now we're getting somewhere! Jon Lane Subject: RE: [teres] Bases and Vibration Date: Sun, 26 Mar 2000 22:34:22 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > This is old hat really . . . . vacuum > hold-down T/Ts exist in the first > place to deal with THIS issue probably more than > record warp. A dear friend of mine and dedicated audiophile actually bought two copies of each favorite record and marked each one with a preferred playing side. His vacuum hold-down platter ruined the other side. Ended up with too much noise to bear... But the Oracle uses a little tapered washer under the record which forces the rim down as the clamp is applied. Jon Lane