Subject: Re: [teres] isodamp; lossy approach is not the best? Date: Wed, 15 Mar 2000 02:31:27 -0700 From: Ivan Anderson, Ivan Anderson To: teres@aiko.com Hello Jon and all, Jon, thanks for your words. I concur, mostly. My approach to this question is to try and 'see' where the vibration waves are, and what they are doing, and answer some questions. Really, the chassis and tonearm mount are the body of a musical instrument, no less so than any guitar or violin. I presume the materials and method of construction must be chosen to provide clear and true tone first, and whatever influence the 'body' might have on the over-all tone is then 'tuned' to give (in this case), the most balanced/accurate representation of live performance possible. It is my aim to remove or render inert any vibration that may interfere with this goal. And so what are vibrations and how do they act? It is my understanding that vibrations are waves travelling a medium, and that they spread out from the source much as ripples in water or, perhaps more appropriately, as heat radiates in metal when heated from a steady source. Indeed an infinite baffle might be just the ticket... Waves can be reflected or refracted or absorbed by the boundaries they meet. Reflection will occur at any boundary/interface if the boundary does not move with the wave perfectly, when this does happen the absorption is perfect. No boundary is perfect. The boundary character can be described by its ability to follow the form of the energy trying to travel through it. This implies compliance and inertia at the boundary must be matched, to ensure maximum passage of vibrational energy from one side to the other. If this process can be continued, eventually the wave will dissipate, or the distance back to the source, if the wave is finally reflected, will be too great for it to have an effect. Of course as soon as you couple a medium to the source you alter the source compliance and inertia, and effectively drive the boundary into the source, and alter dissipation. How best to control the vibration? If I supply a path for it to travel through, the further they travel the lower the energy levels and frequency I will need to deal with. If I can fashion a chassis that initially complies with the movement from the source and then progressively stiffen and damp that movement, sinking for lower and lower frequencies I will be well pleased. The best shelves I have made were 1mm Formica rigidly glued to 13mm of closed cell pvc foam glued to 20mm of granite. I see the foam as a progressive damper, it moves freely with the formica but is constrained by the granite. The best speaker stands I have made have a mild steel rectangular tube top plate in the shape of a capital 'I' (or H rotated 90deg), spikes bolted though the flat of the tube. This is welded to two medium walled pipe posts fore and aft which are free to slide up and down in closely fitting medium walled square tube (50 x 50mm) which in turn is welded to a heavy walled square tube 'T' base. The tube is constrained by a T bolt in each sq. tube leg. A capital I held in place by a capital H (side view) on top of a capital T, if you will. An adjustable stand originally made for recording studios which soon found its way into living rooms. Their good performance is due to the progressive increase in weight and thickness of material but the magic they do to speakers seems to lie in the ability of the pipe to vibrate within the confines of tube and dissipate energy in doing so, as hard welded versions do not perform as well. Food for thought... What I am trying to demonstrate is that, as Jon said, if one can get the vibration away from its source then various methods can be found to deal with it. That is the nub, but in order for something to deal with vibration it must first accept it. Connecting the record to an acrylic platter, if firmly enough coupled, approaches playing a 3" thick record, which should have the stylus moving at full extension, that is another matter. Connecting the tone arm base to something massive at its interface, even if of the same material, does not allow all the energy to flow IMO. Light and rigid to start with, is my philosophy and I'll stick with it... unless it sounds like crap. Ivan. Subject: RE: [teres] isodamp; lossy approach is not the best? Date: Wed, 15 Mar 2000 08:24:08 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com Ivan said, > What I am trying to demonstrate is that, as Jon > said, if one can get > the vibration away from its source then various > methods can be found > to deal with it. That is the nub, but in order > for something to deal > with vibration it must first accept it. > > Connecting the record to an acrylic platter, if > firmly enough coupled, > approaches playing a 3" thick record, which > should have the stylus > moving at full extension, that is another matter. > Connecting the tone > arm base to something massive at its interface, > even if of the same > material, does not allow all the energy to flow IMO. Great analysis, Ivan, and your conclusion is convincing. I've indirectly pondered this in some of my posts and we'll see what the sound says about identical arm/chassis materials in high mass vs. low mass configs. That new Kuzma (?) table has been mentioned here, and if the reviews are accurate, may point to the validity of the lighter approach. Essentially a damped tube between armbase and spindle. Logically, it seems to callout effectively extending the arm base down, back toward the spindle and terminating it there. The material is alloy, like the arm, but not a block or plate, it's a hollow tube filled with the prescribed damping. One of the Teres group has decided to make one also. Betcha it works very well. Jon Lane Subject: Re: [teres] Hello Date: Wed, 15 Mar 2000 08:40:38 -0700 From: Jeremy Epstein, Jeremy Epstein To: Nicholas McKinney; teres Nicholas McKinney wrote: > > At 04:39 PM 3/7/00 -0500, Jeremy Epstein wrote: > > >Hi Nick! > > Hi Jeremy, it was nice meeting at the show. That was a fun time, wasn't it - how was your trip back? Good effort coming up for the show, thanks for participating. Give my best to Bob! > Just got back, only a thousand emails waiting ;-) > > I really wish we could have had a chance to bi-amp with those new Sovtek 2A3 > tubes. MM hmm. Oh well, next time at your place - or Arhus maybe? > I don't really have a time table for this turntable base and no one else is > interested it seems. I plan to try the dual flat bases with inner tube, but I > might also make another one like the turntable that was at the show (ya know, > art statement) > > Let me know what you want to do. I would probably be interested in piggybacking on whatever you decide - I think my aesthetic preference would be for a rectilinear style but I could be persuaded otherwise, the arguments for a skeleton base make good sense to me. In any case, having you guys do all the prototyping and just forking over some cash at the end has a certain appeal! And if we started with rectilinear, I could always break out my PorterCable 6090 and do a little MC (maniacally controlled) machining to get down to a skeleton if necessary afterwards. ;-) I like the look of black Corian, but a deep solid color (flag blue, forest green, ruby red) would actually be much nicer in my book, and maybe those cutouts would be easier to stumble across? I'm not a big fan of flecked "faux granite"-type finishes. Keep me in the loop, I'll bet it will work out well. -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: Re: [teres] Hello Date: Wed, 15 Mar 2000 08:41:41 -0700 From: Jeremy Epstein, Jeremy Epstein To: Nicholas McKinney; teres Nicholas McKinney wrote: > > At 04:39 PM 3/7/00 -0500, Jeremy Epstein wrote: > > >Hi Nick! > > Hi Jeremy, it was nice meeting at the show. That was a fun time, wasn't it - how was your trip back? Good effort coming up for the show, thanks for participating. Give my best to Bob! > Just got back, only a thousand emails waiting ;-) > > I really wish we could have had a chance to bi-amp with those new Sovtek 2A3 > tubes. MM hmm. Oh well, next time at your place - or Arhus maybe? > I don't really have a time table for this turntable base and no one else is > interested it seems. I plan to try the dual flat bases with inner tube, but I > might also make another one like the turntable that was at the show (ya know, > art statement) > > Let me know what you want to do. I would probably be interested in piggybacking on whatever you decide - I think my aesthetic preference would be for a rectilinear style but I could be persuaded otherwise, the arguments for a skeleton base make good sense to me. In any case, having you guys do all the prototyping and just forking over some cash at the end has a certain appeal! And if we started with rectilinear, I could always break out my PorterCable 6090 and do a little MC (maniacally controlled) machining to get down to a skeleton if necessary afterwards. ;-) I like the look of black Corian, but a deep solid color (flag blue, forest green, ruby red) would actually be much nicer in my book, and maybe those cutouts would be easier to stumble across? I'm not a big fan of flecked "faux granite"-type finishes. Keep me in the loop, I'll bet it will work out well. -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: RE: [teres] isodamp; lossy approach is not the best? Date: Wed, 15 Mar 2000 09:44:40 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Jon: Thanks for taking the time and patience to reply to my uncertaincies about your proposed methods. Your detailed description is very compelling and doesn't seem to violate any laws of physics. You've obviously thought things through very thoroughly; more so than I have, and I will have to give it more thought and/or listen to results before I can argue intelligently with it. You also have explained your speaker box analogy succinctly. Cheers, Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Jon Lane [SMTP:jhlane@email.msn.com] > Sent: Tuesday, March 14, 2000 7:50 PM > To: teres@aiko.com > Subject: RE: [teres] isodamp; lossy approach is not the best? > > Ken said: > > > I've read your theses carefully, but I struggle > > with the statement "ability > > for all energy to appear at all places." That > > statement appears to violate > > the basic laws of physics as I understand them, > > and thus reduces the > > effectiveness of your argument in my mind. > > I don't mean to suggest that what's going on is a trendy, > audiophile violation of physics - quite the opposite but > without the formal definitions, I'd hoped. Once again just > to be sure, my stuff is just me thinking out loud and my > experiential basis is still lacking absolute verification - > much of this is street-level theory co-mingled with equal > parts instinct and empirical results. Obviously, we could > use some finer analysis. > > However, I'll take another shot at it since I brought it up. > > Concerning chassis, I think I see it this way. We have four > choices: > > 1. Rigid, conductive chassis; > 2. Rigid, non-conductive chassis; > 3. Compliant, conductive chassis, and; > 4. Compliant, non-conductive chassis. > > These are relative terms, please bear with me... > > 1. We select the most rigid, most "vibrationally > conductive" material we can find (aluminum comes to mind), > thus ensuring that - just like the plastic platter/plastic > record Teres design - we provide a low-impedance path for > any energy transmitted down the armtube to dissipate into > the chassis. Essentially, the "mechanical diode" - once it > leaves the arm, it ain't getting back in there (and I agree > 100% with my understanding of Igor's point - pointed feet > aren't diodes, despite their shape). Any impedance mismatch > whatsoever at the arm/chassis junction reduces the ability > of the relatively uncontrolled arm to deal with the > ferocious HF content cut into the RIAA eq curve. (Ever > notice how much cry cheap headshells give off?) Again, the > platter is doing it's job with regard to energy exiting in > *that* direction, we need to turn our attention to the only > other path for energy leaving the stylus: the arm, most of > them being rigid, alloy affairs with fixed bearings. > > Turning next to chassis rigidity, we next use a lot of > material, aiding it dramatically. We should find that of > service in ensuring that no compliance occurs between the > moving parts, which, I'm thinking, aids fundamentals, > especially in the lowest octaves. (Motion is only by way of > compliance between arm and platter, thus describing an > entirely new, but lower set of problem frequencies. Our > concept #1 prohibits this occurring.) > > Last, we damp the whole affair to taste, having thus ensured > both HF sinking/attenuation and LF stability. > > 2. We select a rigid chassis, but with impaired impedance > matching. Say, a block of ceramic or stone. All of the > above remain in place regarding a intimate connection > between parts, but this time with HF sinking worsening with > increasing frequency. We reflect increasingly more energy > back up the arm base and into the tube as we increase > frequency, not a very good thing given the RIAA curve. Low > frequency fundamentals remain strong, but HF hash appears at > the playing end of the machine that wasn't there before. > > 3. Next, we make basically a thin version of #1. A good > mechanical match once again which aids the HF losses. Maybe > a plate metal chassis. Our HF match and sinking returns > somewhat, but isn't as effective for reasons of limited > volume to attenuate the energy as well. Things presumably > get even worse when we lose our ability to rigidly constrain > the parts and we find new reactances in the lower ranges. > All in all, we've saved mass and money, but kept only some > of the benefits of allowing the arm to "talk" to the > chassis. Plus, we've developed a loss of mechanical > integrity creating a reactance somewhere in the lower > octaves. > > 4. Finally, we make a design both compliant and poorly > matched. We lose all of the previous benefits. This is > partially the fear I have in using a material or materials > with a strong fundamental internal mode at a lower frequency > unable to be corrected by any means. With a sandwich of > wood and lead, you lose both energy coupling to the arm, as > well as risking severe suseptance to external influences, > the frequencies below 1kHz being far more powerful and > difficult to stop in typical listening systems. Depending > on the mass of this structure, we are creating a reservoir > for energy to bounce around it at frequencies low enough we > cannot control them. > > It seems we've learned that we want to ensure a good > impedance match between arm and chassis. We've speculated > further that a rigid loop aids the bass for reasons > apparently related to ensuring zero motion between the parts > and rejection of external input. I don't know the precise > reason why, but I've found that such designs do have a > better bottom. > > Now, things get complex again when we consider that any of > the above can be built either as lightweights or as > heavyweights. The tonearm "sinking" changes once again, > presumably in favor of the heavy designs, and rigidity is > inherently connected to the amount of any given material, > again with the benefit going to the heavier design. The > only downside is that we lower the fundamental resonance > although we don't increase internal suseptance to the > outside input while doing so. > > The only remaining thing, as I see it, is to critically damp > any energy in the system put there by internal influences > like the cartridge. I have suggested performing this task > after the machine is built and able to be tested, and I'd > planned to observe the behavior of energy applied by a > transducer to the arm location at various points across the > surface of the chassis. While fairly crude, it seems to me > that using a scope and pickup, one could progressively damp > the surfaces until the best compromise between acceptance > and rejection across the frequencies in question came about. > Anyone? > > > Other points of your thesis > > also seem alien to me. You want a lossless > > mechanical loop; in my mind that > > would return energy sunk into it back to the > > stylus, only delayed as it > > travels through the loop. > > I can't help but think > > of that process as delayed > > feedback, which is loved by the transistor crowd > > but has no place in my > > life. > > That delayed feedback is probably why > > Linns and Oracles don't have > > the "blackness" of a SOTA or Maplenoll, as you > > point out. > > I understand your point, but if the assembly is critically > damped, this energy reappears only "once", at a greatly > attenuated level, and is attenuated rapidly after that. > This first appearance is far, far less destructive however, > than leaving it in the arm, which is the risk of not sinking > it at all. > > > Correct me if I'm > > wrong, but I suspect that the resultant sound of > > a "bright" base would be > > brighter than that of a "lossy" system. > > Actually, if this theory holds, the reverse may be true... > Tables I've made even with no damping of conductive chassis > have far better resolution through draining the excess noise > away from the cart, although they generally ended up > benefiting from progressive damping as we dialed them in. > The thing I think we need to keep in mind is the extreme > susceptibility of undamped conductive chassis to *external* > input. Frankly, an entire post could/should be written > attempting to qualify this effect as well. Personally, I > prefer to see this is a separate problem and limit my > efforts to dealing with only the energy within the loop. > But then if you listen at levels above 90dB with the table > close to the speakers... > > > One has > > to listen to decide if > > brighter is better. I remain allied to a > > "massive, lossy base," as Grant > > aptly described it. > > Bright only if you don't damp properly. The heavy lossy > base has been seen to reject input in the first place thus > throwing away the benefits of sinking unwanted energy away > from far more delicate parts like bearings, armtubes, and > cartridges. > > > As an amateur speaker designer, I don't > > understand how you equate an > > undersize speaker boss to a lossy TT base. An > > undersize speaker boss has a > > high Q and requires more damping, just the > > opposite of a lossy base. As you > > say, the analogy is indeed inverted, but I'm > > unable to set it aright. > > An undersized box is underdamped, and cannot be brought to a > state of Q=0.5, or critical damping. A large box can; throw > some bricks in there [rolls eyes - this analogy sucks] to > decrease its internal volume to bring it from say, Q=0.4 to > Q=0.5. Likewise, undamped energy left in the arm cannot be > brought into a state of critical damping without first > allowing it to dissipate as freely as possible. Once having > done so (and with its relative level conveniently > diminished), you can commence to critically damp it. The > small box is discarded just as the low-admittance chassis > would be - there is no fix. OTOH, the larger box can easily > be partially filled in order to raise it's Q. A very clumsy > analogy, but it worked for me... > > > I view our dissimilar philosophies as very > > constructive, especially in this > > format. > > I do too. Looking forward to further comment and > enlightenment. > > > Each of us will ultimately construct our > > TT bases according to our > > beliefs and tastes, and we can profit by the > > ideas of others in doing so. I > > only hope I have the opportunity to hear the > > results of different designs. > > You're always welcome. > > Jon Lane > Subject: Re: [teres] Hello Date: Wed, 15 Mar 2000 11:57:01 -0700 From: Nicholas McKinney, Nicholas McKinney To: teres@aiko.com At 10:49 PM 3/14/00 -0700, you wrote: >Hi, Nick > >> Hi Al, well alot like this picture I would imagine; >> >> http://www.audioadvancements.com/amazon1.htm > >I like the looks of the that. >> >> I plan to make a recess in each flat panel sized perfectly for a tube shaped >> air bladder, then leave about 0.1~0.2" of space between them when inflated. > >Would you be doing the recesses via CNC machining too? How difficult would >it be to delete this part of the process? I was thinking of resting the >whole works on top of a sandbox, and the sandbox on the air bladders. Hi Steve, yes on the CNC. Its super easy to not include it, the cost for the piece would be much less too. >> The motor would be on the bottom panel and pass through an access hole on the >> upper. >> >> In my case the motor on the lower panel would be replaced by an "idler >> bearing" >> and the motor moved outboard. This idler bearing would have a dual groove >> pulley, one groove carrys the belt for the platter, and the other groove >> carries another belt to the motor. This should "theoretically" lower the >> motor >> vibrations and speed changes to the platter. > >I am one of the people Thom mentioned that wants to avoid this complexity. >8^) Yeah, I can relate. I have never done it in practice either so I don't know how much gain can be realized over just the motor. cya Nick Subject: Re: [teres] isodamp; lossy approach is not the best? Date: Wed, 15 Mar 2000 13:40:30 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com How Zen, Ivan ... I *love* it! Thom ----- Original Message ----- From: Ivan Anderson To: Sent: Wednesday, March 15, 2000 1:23 AM Subject: Re: [teres] isodamp; lossy approach is not the best? Hello Jon and all, [ lots of good, thought provoking stuff snipped ] What I am trying to demonstrate is that, as Jon said, if one can get the vibration away from its source then various methods can be found to deal with it. That is the nub, but in order for something to deal with vibration it must first accept it. [ snip ] Ivan. __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] isodamp; lossy approach is not the best? Date: Wed, 15 Mar 2000 18:27:08 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com Regarding the Lossy or rigid argument on the Record, Platter, bearing, chassis, arm, and cartridge needle, and back to the record interface (loop), I believe that the trick is to damp as much as possible but do not have any type of slope to do so. Vibrational energy traveling in any material is going to bounce around and do all sorts of nasty stuff that will alter the original waveform. That energy needs to be directed somewhere, where it won't be picked up again. The idea of a perfect loop where energy arrives back at the source in sync with the original signal is impossible given the scale of structures we are dealing with. But I do agree will Jon and Tom on the idea that we don't won't the arm support moving at different rates then the platter/bearing in the audio spectrum. At low frequencies or large relative movements the structure must act as one unit. However, bearing noise (even if very little) must not be rigidly coupled to the arm board. How do you achieve both goals? 1) Make the bearing to plinth support as rigid as practical. 2) Design the plinth supports to sink small scale higher frequencies into some structure that can effectively turn this energy into heat. 3) Make the arm board massive so that it can not easily be excited into vibration modes. 4) Rigidly couple the arm board to the plinth so that large scale movements can not effect one without effecting the other. 5) Decouple the arm board to the plinth so that as frequencies increase the arm board is more and more decoupled from the plinth. Note that as frequencies increase the associated harmonics generated by the transmitting media will increase in number and time distortions will also increase up to a limit. 6) I plan to achieve item 5 by having a gasket of sorbothane under the armboard and the armboard will be drilled with holes to accept silicon tubing, through the tubing I will have SS cap screws that will secure the armboard to the plinth. The tubing will extend slightly beyond the shoulder of the holes in the armboard. This will allow the use of washers on top of the silicon tubing to compress the tubing as the cab screws are tightened. As the cap screws are tightened not only will the tubing be compressed, but so will the sorbothane gasket. I plan on using at least 4 compression assemblies for the arm board. All holes will be counter sunk so that the cap screw heads will not extend above the top surface of the armboard. I think this will allow me to effectively tune the decoupling of the arm board to achieve the best of both worlds. A rigid interface that will not transmit mechanical noise, but instead sink the energy to minimize noise pick up by the cartridge other than what it tracks. Subject: [teres] Cu Date: Wed, 15 Mar 2000 19:10:07 -0700 From: phclark, phclark To: Teres My apologies to those who posted me privately about copper. The volume of mail on the List long ago made nonsense of my filing system for keeping track of specific subjects. Pursuant to the Mega Remodel, I had occasion today to go to the salvage yard (actually to get brackets for the shelving in my, *ta-da,* dedicated LP storage **room**!!!!). (I've been without vinyl, essentially, since 6/99, and yes, the twitching has now become uncontrollable.) A casual peruse revealed usable quantities of 2", 2.5", 3", 3.75" and 4" ID copper pipe, generally with .125" wall. I think there was some 6", as well. It's $2.50/lb. and they will cut it, though I don't know how short they will cut any section. Practically, my guess is about 3". They use a big chop saw, so the cuts are square and fairly clean, but not as though they were parted off on a lathe. They also have sheet goods in approximately 12" x 18" from, my guess, 18 ga. up to about .125". I've used this for chassis before and it works fine. Also $2.50/lb.. (I also scored a 8# machined (vent-a-ports!) brass casting, 12" dia x 2.5" H for use as a platter base. Eat your hearts out.) If you are interested in some of this copper, please let me know what you are looking for. I'll be going back fairly regularly in the foreseeable future as I get closer to implementing the Teres motor pod and arm thing. We can work out specifics as required. Peter C Subject: Re: [teres] isodamp Date: Wed, 15 Mar 2000 21:13:18 -0700 From: Jon Lane, Jon Lane To: Teres@Aiko.Com Igor said, > Using a tapered metal plate, with > the large end drilled for, and attached to the > structure we want to sink vibrations *from* (just like > a heat sink)...The tapered end (to a point possibly) > would not contact any other metal. The taper would > discourage standing waves within the metal piece, just > as the taper in a TL would, and progressively > terminate the metal/other material interface. Interesting, how speaker analogies keep cropping up...naturally: both are transducers. Have you thought about putting the arm at the *small* end of a flared piece? Just like a T-line has its' function, so does a horn... Jon Lane Subject: Re: [teres] Cu Date: Wed, 15 Mar 2000 22:01:00 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com In a message dated 3/15/00 6:11:34 PM Mountain Standard Time, phclark@uswest.net writes: << If you are interested in some of this copper, please let me know what you are looking for. I'll be going back fairly regularly in the foreseeable future as I get closer to implementing the Teres motor pod and arm thing. We can work out specifics as required. >> I'm interested in some thick stuff 1/4" or greater. I would like to get some 1/2" to 3" thick stuff for an arm board. Thanks for asking. Until again Gordon Subject: Re: [teres] isodamp; lossy approach is not the best? Date: Thu, 16 Mar 2000 00:33:15 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com 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 ----- Original Message ----- From: To: Sent: Wednesday, March 15, 2000 4:23 PM Subject: Re: [teres] isodamp; lossy approach is not the best? > Regarding the Lossy or rigid argument on the Record, Platter, bearing, > chassis, arm, and cartridge needle, and back to the record interface (loop), > I believe that the trick is to damp as much as possible but do not have any > type of slope to do so. Vibrational energy traveling in any material is going > to bounce around and do all sorts of nasty stuff that will alter the original > waveform. That energy needs to be directed somewhere, where it won't be > picked up again. The idea of a perfect loop where energy arrives back at the > source in sync with the original signal is impossible given the scale of > structures we are dealing with. But I do agree will Jon and Tom on the idea > that we don't won't the arm support moving at different rates then the > platter/bearing in the audio spectrum. At low frequencies or large relative > movements the structure must act as one unit. However, bearing noise (even if > very little) must not be rigidly coupled to the arm board. How do you achieve > both goals? > 1) Make the bearing to plinth support as rigid as practical. > 2) Design the plinth supports to sink small scale higher frequencies into > some structure that can effectively turn this energy into heat. > 3) Make the arm board massive so that it can not easily be excited into > vibration modes. > 4) Rigidly couple the arm board to the plinth so that large scale movements > can not effect one without effecting the other. > 5) Decouple the arm board to the plinth so that as frequencies increase the > arm board is more and more decoupled from the plinth. Note that as > frequencies increase the associated harmonics generated by the transmitting > media will increase in number and time distortions will also increase up to a > limit. > 6) I plan to achieve item 5 by having a gasket of sorbothane under the > armboard and the armboard will be drilled with holes to accept silicon > tubing, through the tubing I will have SS cap screws that will secure the > armboard to the plinth. The tubing will extend slightly beyond the shoulder > of the holes in the armboard. This will allow the use of washers on top of > the silicon tubing to compress the tubing as the cab screws are tightened. As > the cap screws are tightened not only will the tubing be compressed, but so > will the sorbothane gasket. I plan on using at least 4 compression assemblies > for the arm board. All holes will be counter sunk so that the cap screw heads > will not extend above the top surface of the armboard. I think this will > allow me to effectively tune the decoupling of the arm board to achieve the > best of both worlds. A rigid interface that will not transmit mechanical > noise, but instead sink the energy to minimize noise pick up by the cartridge > other than what it tracks. Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 01:01:18 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Yes, I did. Igor --- Jon Lane wrote: > Igor said, > > > Using a tapered metal plate, with > > the large end drilled for, and attached to the > > structure we want to sink vibrations *from* (just > like > > a heat sink)...The tapered end (to a point > possibly) > > would not contact any other metal. The taper > would > > discourage standing waves within the metal piece, > just > > as the taper in a TL would, and progressively > > terminate the metal/other material interface. > > Interesting, how speaker analogies keep cropping > up...naturally: both are transducers. > > Have you thought about putting the arm at the > *small* end of > a flared piece? Just like a T-line has its' > function, so > does a horn... > > Jon Lane > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] isodamp Date: Thu, 16 Mar 2000 01:49:18 -0700 From: Sellek, Grant (TSA), Sellek, Grant (TSA) To: 'teres@aiko.com' Thanks for this discussion, Steve. What sort of thickness of metal and Corian are you thinking of? And when you say "bonded", do you mean glued together? Grant Grant Sellek Adelaide, Australia grant.sellek@transport.sa.gov.au -----Original Message----- From: Steve Zettel [mailto:zettel@libby.org] Sent: Thursday, 16 March 2000 3:47 pm So, before I change my mind in response to the next argument that comes along, I envision a subchassis made of a sheet of steel or aluminum bonded tightly to a piece of Corian with a thin layer of Dynamat between. This sandwich supports the bearing and the armboard. It rests on a very thin layer of sorbothane on top of a larger slab of Corian or marble or acrylic. This slab is large enough to also have the heavy motor pod resting on top (on it's own very thin layer of sorbothane), but not in contact with the subchassis. This bottommost slab is resting flat on top of the sand in the sandbox, in intimate contact over all of it's bottom surface. More energy dissipation. Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 02:21:37 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/16/00 00:49, Sellek, Grant (TSA) at Grant.Sellek@transport.sa.gov.au wrote: > Thanks for this discussion, Steve. What sort of thickness of metal and > Corian are you thinking of? And when you say "bonded", do you mean glued > together? Well, I haven't done any research at all yet on adhesives, so I don't know if any are available that would be very thin yet non-pliable between steel and Corian, say, and still make a permanent bond. I might go with thru-bolting instead. The top could be a socket head cap bolt, and underneath instead of a nut, a cone tapped to accept the bolt. One of suitable diameter at each corner, with the bearing housing nut in the middle, should be enough to secure the works together. The Corian (or MDF, or acrylic) will be 3/4" or 1", the steel or aluminum not thicker than 1/4". However, Nick makes the point that Corian by itself is quite stiff and non-bendable. I have the feeling whatever I do, and whatever configuration, my turntable is going to look "industrial-tech" rather than drawing-room elegant. Steve Z > > Grant > > Grant Sellek > Adelaide, Australia > grant.sellek@transport.sa.gov.au > > > -----Original Message----- > From: Steve Zettel [mailto:zettel@libby.org] > Sent: Thursday, 16 March 2000 3:47 pm > > > > So, before I change my mind in response to the next argument that comes > along, I envision a subchassis made of a sheet of steel or aluminum bonded > tightly to a piece of Corian with a thin layer of Dynamat between. This > sandwich supports the bearing and the armboard. It rests on a very thin > layer of sorbothane on top of a larger slab of Corian or marble or acrylic. > This slab is large enough to also have the heavy motor pod resting on top > (on it's own very thin layer of sorbothane), but not in contact with the > subchassis. This bottommost slab is resting flat on top of the sand in the > sandbox, in intimate contact over all of it's bottom surface. More energy > dissipation. > Subject: Re: [teres] Cu Date: Thu, 16 Mar 2000 02:21:38 -0700 From: Brian, Brian To: teres@aiko.com My brother is a very large volume wholesaler of copper and aluminum tubing. I'm not sure what your use is for copper/aluminum tubing but I am certain I could get a good deal on either. He may be able to have it fabricated as well. Brian ----- Original Message ----- From: phclark To: Teres Sent: Wednesday, March 15, 2000 5:59 PM Subject: [teres] Cu > My apologies to those who posted me privately about copper. The volume of > mail on the List long ago made nonsense of my filing system for keeping > track of specific subjects. > > Pursuant to the Mega Remodel, I had occasion today to go to the salvage yard > (actually to get brackets for the shelving in my, *ta-da,* dedicated LP > storage **room**!!!!). (I've been without vinyl, essentially, since 6/99, > and yes, the twitching has now become uncontrollable.) A casual peruse > revealed usable quantities of 2", 2.5", 3", 3.75" and 4" ID copper pipe, > generally with .125" wall. I think there was some 6", as well. It's > $2.50/lb. and they will cut it, though I don't know how short they will cut > any section. Practically, my guess is about 3". They use a big chop saw, > so the cuts are square and fairly clean, but not as though they were parted > off on a lathe. > > They also have sheet goods in approximately 12" x 18" from, my guess, 18 ga. > up to about .125". I've used this for chassis before and it works fine. > Also $2.50/lb.. > > (I also scored a 8# machined (vent-a-ports!) brass casting, 12" dia x 2.5" H > for use as a platter base. Eat your hearts out.) > > If you are interested in some of this copper, please let me know what you > are looking for. I'll be going back fairly regularly in the foreseeable > future as I get closer to implementing the Teres motor pod and arm thing. > We can work out specifics as required. > > Peter C > > Subject: Re: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 04:40:11 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Thank you Daus, and welcome back. I've been trying to say something much like this to the "rigid & ringy" chassis camp, but haven't had the time to explain my viewpoint very well. If I remember correctly, and also for the benefit of those recent to our group, you are a formal student of acoustics, correct? My viewpoint is that the best materials should be rigid *and* lossy, not rigid vs. lossy, and certainly *not* flexible/deformable. I believe that "lowly" MDF is indeed an *excellent* material for the purpose, especially if augmented with something like a wrap of even more rigid/ internally well damped carbon fiber/epoxy, using MDF/lead/MDF or MDF/Isodamp/MDF as an actively desirable, inexpensive, practically workable spacer core. This is far better than using a highly transmissive material, like metal, to form a "perfect loop" between the arm and platter, damped or not. It takes *time* for vibration to travel, so it simply cannot magically appear "everywhere at the same time", as in Jon's conception, as that is patently **impossible**. Fixing that relationship rigidly for stability, so that everything stays "put" relatively (or "moves together", if you like), is critical, but that should be done with a material which can "extract" the vibration, and kill it, not pass it on happily back and forth between the arm & platter. When a platter/chassis/arm/cartridge circuit is formed with a highly transmissive material like the frequently proposed Stainless Steel, vibrational energy will, as observed below, "bounce around and do all sorts of nasty stuff", ending up back at the stylus, of course. There is also an old engineering term to cover some aspects of that condition - "feedback loop". Sinking vibration from those parts can be accomplished *without* linking them with a "live" connection, or using more than a minimum of, if any, "ringing" materials, as I suggested in a possible configuration yesterday. Others are possible. Vibration *can* be extracted & quelled without resorting to the use of metal parts, which form "echo chambers" within the TT structure. As for the transmittance of low frequency floor-borne noise, the subject of chassis "Q" tuning considerations in another post, well, that's what a good air suspension underneath it all is good for (not that anything will kill that completely). More on the general subject, time permitting. Igor --- Daus Studenberg wrote: > 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 > > ----- Original Message ----- > From: > To: > Sent: Wednesday, March 15, 2000 4:23 PM > Subject: Re: [teres] isodamp; lossy approach is not > the best? > > > > Regarding the Lossy or rigid argument on the > Record, Platter, bearing, > > chassis, arm, and cartridge needle, and back to > the record interface > (loop), > > I believe that the trick is to damp as much as > possible but do not have > any > > type of slope to do so. Vibrational energy > traveling in any material is > going > > to bounce around and do all sorts of nasty stuff > that will alter the > original > > waveform. That energy needs to be directed > somewhere, where it won't be > > picked up again. The idea of a perfect loop where > energy arrives back at > the > > source in sync with the original signal is > impossible given the scale of > > structures we are dealing with. But I do agree > will Jon and Tom on the > idea > > that we don't won't the arm support moving at > different rates then the > > platter/bearing in the audio spectrum. At low > frequencies or large > relative > > movements the structure must act as one unit. > However, bearing noise (even > if > > very little) must not be rigidly coupled to the > arm board. How do you > achieve > > both goals? > > 1) Make the bearing to plinth support as rigid as > practical. > > 2) Design the plinth supports to sink small scale > higher frequencies into > > some structure that can effectively turn this > energy into heat. > > 3) Make the arm board massive so that it can not > easily be excited into > > vibration modes. > > 4) Rigidly couple the arm board to the plinth so > that large scale > movements > > can not effect one without effecting the other. > > 5) Decouple the arm board to the plinth so that as > frequencies increase > the > > arm board is more and more decoupled from the > plinth. Note that as > > frequencies increase the associated harmonics > generated by the > transmitting > > media will increase in number and time distortions > will also increase up > to a > > limit. > > 6) I plan to achieve item 5 by having a gasket of > sorbothane under the > > armboard and the armboard will be drilled with > holes to accept silicon > > tubing, through the tubing I will have SS cap > screws that will secure the > > armboard to the plinth. The tubing will extend > slightly beyond the > shoulder > > of the holes in the armboard. This will allow the > use of washers on top of > > the silicon tubing to compress the tubing as the > cab screws are tightened. > As > > the cap screws are tightened not only will the > tubing be compressed, but > so > > will the sorbothane gasket. I plan on using at > least 4 compression > assemblies > > for the arm board. All holes will be counter sunk > so that the cap screw > heads > > will not extend above the top surface of the > armboard. I think this will > > allow me to effectively tune the decoupling of the > arm board to achieve > the > > best of both worlds. A rigid interface that will > not transmit mechanical > > noise, but instead sink the energy to minimize > noise pick up by the > cartridge > > other than what it tracks. > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 04:44:22 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Good points, Steve. Igor --- Steve Zettel wrote: > Hello, all > > Several thoughts occur to me about the various > chassis arguments so far: > > The idea of impedance matches is an attractive one, > but ultimately fails > because at any discontinuity, even between two > identical materials bolted > tightly together there will be some energy reflected > back. > > Several people have used the idea of an acrylic > platter as a sink for vinyl > vibrations, or made the statement that vinyl and > acrylic are well-matched, > impedance wise. Well, maybe more so than aluminum, > but I think we discussed > this early on. The only way to ensure a > low-impedance junction between the > platter and the record would be to make the platter > out of vinyl, and bond > the record tightly to it all over its surface. If > the rigid, stiff crowd was > truly carrying their argument through, the bearing, > housing, sub or chassis, > armboard, AND the platter would all be made out of > SS or AL, ditto the arm. > > (I have tried my experiments again with my two > sorbothane mats, the acrylic > mat and the bare aluminum platter now that I have my > Clearaudio Sigma pretty > well broken in. Same results as before: the hard > acrylic and especially the > bare platter seem artificially bright, but worse, > harmonically incorrect. > Ken had talked about the "detail" of the stiff, > rigid undamped designs being > an addition of vibrational energy at the cartridge, > and I would tend to > agree. But this is perhaps only true of the platter > and mats). > > The stiff, undamped argument does not fully address > some other phenomena: > > If we could make everything of a piece with perfect > impedance-matched > junctions, so no energy is reflected at junctions, > there still is some > amount of lag time before a noise impulse or energy > spike (or vibration) > travels from it's origin to some other point. You > can't have all parts > instantaneously accelerated, and in phase, to boot. > If there is no relative > motion between parts, then there is no extraneous > signal - all parts are > moving in concert. But who can predict what phase > the signal from chassis is > going to be at the end of the tonearm. Or any other > point. > > Also, the junction between the surface of all parts > and the surrounding > air, is a large impedance mismatch, which reflects > most of the energy > reaching this boundary right back in where it > continues to ring. And, just > as we find in driver physics, surface area > mismatches, instead of smooth > transitions or gently flaring throats in a horn, > also reflect a portion of > the energy. A large, stiff piece of metal that > resists bending will > definitely transmit energy. The tonearm, no matter > how tightly coupled at > the armboard, and no matter what the material, has > to be free to move, else > it could not trace the record grooves. This energy > will excite the tonearm > at some characteristic frequency and it WILL be free > to vibrate (ever see > the whip-style radio antenna on a car or truck start > vibrating violently > even though the car body was motionless to the naked > eye, as the motor was > revved?). > > The argument was made that high frequency vibrations > are short sharp spikes > of high amplitude and short duration, low frequency > vibrations are longer in > duration (but for the same amount of energy will be > lower in amplitude). Can > we ensure that all vibrations propagated through our > material will be so > high (but unfortunately higher in amplitude as well) > that they will be above > the ability of the cantilever of the cartridge to > respond? Low frequency > (but low amplitude) vibrations are *bad*, because > they are stretched out > over time and cause smearing of the sound. But ONLY > if they are of high > enough amplitude to be above the threshold to which > the cantilever can > respond. Now we are shaking the back end of our > cartridge's generator > relative to the cantilever! > > My thought is we want our chassis material rigid > enough so that there is no > relative motion between platter, bearing and > armboard, inert enough that > vibrational energy is not readily propagated, and > damped enough that what > energy *is* propagated is rapidly attenuated below > the response threshold of > the cartridge's generator. > > One or two rigid sheets of aluminum or steel, > sandwiching a core of inert > foam or honeycomb (like the old Hexcel skis) might > be one configuration. > Carbon fiber might be another. So might a flat sheet > of acrylic sandwiched > or at least backed by a sheet of steel or aluminum > plate. Corian might work > here too, as might MDF. > > The damping might come from a thin layer of > sorbothane, isodamp, or the > auto-sound favorite, Dynamat, contrained within the > sandwich (though I want > to be careful not to make the sandwich "squishy" or > dimensionally unstable > as that would defeat the idea of rigidity and no > relative motion between the > parts mounted to it). I don't want to get into > "tuning" my table by > adjusting the torque of the bearing securing nut > squeezing on the subchassis > sandwich! Certainly, a layer of damping under the > subchassis is a good idea. > > So, before I change my mind in response to the next > argument that comes > along, I envision a subchassis made of a sheet of > steel or aluminum bonded > tightly to a piece of Corian with a thin layer of > Dynamat between. This > sandwich supports the bearing and the armboard. It > rests on a very thin > layer of sorbothane on top of a larger slab of > Corian or marble or acrylic. > This slab is large enough to also have the heavy > motor pod resting on top > (on it's own very thin layer of sorbothane), but not > in contact with the > subchassis. This bottommost slab is resting flat on > top of the sand in the > sandbox, in intimate contact over all of it's bottom > surface. More energy > dissipation. > > Just my 2 cents worth. > > Steve Z > near Libby, MT > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] isodamp; lossy approach is not the best? Date: Thu, 16 Mar 2000 08:42:01 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Gordon: An excellent analysis with which I agree. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: MaughanAudio@aol.com [SMTP:MaughanAudio@aol.com] > Sent: Wednesday, March 15, 2000 5:23 PM > To: teres@aiko.com > Subject: Re: [teres] isodamp; lossy approach is not the best? > > Regarding the Lossy or rigid argument on the Record, Platter, bearing, > chassis, arm, and cartridge needle, and back to the record interface > (loop), > I believe that the trick is to damp as much as possible but do not have > any > type of slope to do so. Vibrational energy traveling in any material is > going > to bounce around and do all sorts of nasty stuff that will alter the > original > waveform. That energy needs to be directed somewhere, where it won't be > picked up again. The idea of a perfect loop where energy arrives back at > the > source in sync with the original signal is impossible given the scale of > structures we are dealing with. But I do agree will Jon and Tom on the > idea > that we don't won't the arm support moving at different rates then the > platter/bearing in the audio spectrum. At low frequencies or large > relative > movements the structure must act as one unit. However, bearing noise (even > if > very little) must not be rigidly coupled to the arm board. How do you > achieve > both goals? > 1) Make the bearing to plinth support as rigid as practical. > 2) Design the plinth supports to sink small scale higher frequencies into > some structure that can effectively turn this energy into heat. > 3) Make the arm board massive so that it can not easily be excited into > vibration modes. > 4) Rigidly couple the arm board to the plinth so that large scale > movements > can not effect one without effecting the other. > 5) Decouple the arm board to the plinth so that as frequencies increase > the > arm board is more and more decoupled from the plinth. Note that as > frequencies increase the associated harmonics generated by the > transmitting > media will increase in number and time distortions will also increase up > to a > limit. > 6) I plan to achieve item 5 by having a gasket of sorbothane under the > armboard and the armboard will be drilled with holes to accept silicon > tubing, through the tubing I will have SS cap screws that will secure the > armboard to the plinth. The tubing will extend slightly beyond the > shoulder > of the holes in the armboard. This will allow the use of washers on top of > > the silicon tubing to compress the tubing as the cab screws are tightened. > As > the cap screws are tightened not only will the tubing be compressed, but > so > will the sorbothane gasket. I plan on using at least 4 compression > assemblies > for the arm board. All holes will be counter sunk so that the cap screw > heads > will not extend above the top surface of the armboard. I think this will > allow me to effectively tune the decoupling of the arm board to achieve > the > best of both worlds. A rigid interface that will not transmit mechanical > noise, but instead sink the energy to minimize noise pick up by the > cartridge > other than what it tracks. Subject: RE: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 08:53:46 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com Igor, I tend to think your comments include a certain amount of intentional wrench throwing. Let's review: > I've been trying to > say something much like this to the "rigid & ringy" > chassis camp, but haven't had the time to explain my > viewpoint very well. There is no rigid and "ringy" camp in all of audio that I can find, certainly not here. All mentions of impedance matching have included liberal discussion of damping, yours included. > If I remember correctly, and > also for the benefit of those recent to our group, you > are a formal student of acoustics, correct? My > viewpoint is that the best materials should be rigid > *and* lossy, not rigid vs. lossy, and certainly *not* > flexible/deformable. Exactly what's been pondered before by the rest of us. Rigid for reasons of impedance matching, not reflection, and lossy *after* this ensured to critically damp the energy. Had you read more carefully, you would have seen that my material on that point was...I think you called it "long-winded." > I believe that "lowly" MDF is > indeed an *excellent* material for the purpose, > especially if augmented with something like a wrap of > even more rigid/ internally well damped carbon > fiber/epoxy, using MDF/lead/MDF or MDF/Isodamp/MDF > as an actively desirable, inexpensive, practically > workable spacer core. Raw MDF is not rigid. MDF *will* resonate like crazy and at a frequency you can't control. Already tried it. Now, if you constrain it, it will be far better behaved, but then you're actually describing something *closer* to damping a material with good - but not excellent - transmissive characteristics. Any losses in the constraining adhesive will still create fundamental resonances unless you bond with crystalline-like agents - at which point you're back to rigid but *not* transmissive. Given the energy RIAA and relatively light arms put into the system, I then question exactly which frequency spectrum you plan to absorb or reflect and in what amounts? > This is far better than using a > highly transmissive material, like metal, to form a > "perfect loop" between the arm and platter, damped or > not. > It takes *time* for vibration to travel, so it > simply cannot magically appear "everywhere at the same > time", as in Jon's conception, as that is patently > **impossible**. Nonsense. Appearing everywhere at the same time is generalization intended to demonstrate that you will have to contend with doing something about the energy put there in the HF's by the arm. I'd guess most of us are reasonably familiar with the concept of time as a function of transmission, wouldn't you agree? OTOH, your lossy sandwich *guarantees* having to deal with increasing amounts of far higher level energy entering the system from outside, a vastly stronger influence and one weighted toward the lower octaves. This energy *will not* appear everywhere, preferring instead to modulate this bendy laminated base you're suggesting everything be bolted to. Unless you don't plan to use an RIAA inversion anywhere in your electronics... > Fixing that relationship rigidly for > stability, so that everything stays "put" relatively > (or "moves together", if you like), is critical, but > that should be done with a material which can > "extract" the vibration, and kill it, not pass it on > happily back and forth between the arm & platter. That's precisely the question we're trying to answer... Have you read the posts on measuring the chassis for critical damping? > When a platter/chassis/arm/cartridge circuit is formed > with a highly transmissive material like the > frequently proposed Stainless Steel, vibrational > energy will, as observed below, "bounce around and do > all sorts of nasty stuff", ending up back at the > stylus, of course. Wrong. Only if (1) this energy appears in bucketfuls from some equally "magical" source in the HF's, something the tonearm simply cannot impress on 10 or 20 lbs of material, (2) if the chassis isn't damped at all, (3) if the attenuation of mass magically disappears again once the energy selectively finds it's way back to the arm base, and (4) if the arm can then accept said energy in precisely the same frequencies it emitted it at will it end up back at the stylus, of course. > There is also an old engineering > term to cover some aspects of that condition - > "feedback loop". Sinking vibration from those parts > can be accomplished *without* linking them with a > "live" connection, or using more than a minimum of, if > any, "ringing" materials, as I suggested in a possible > configuration yesterday. "Live connections" are impossible to avoid. One *must* however, select the frequencies and amplitudes - internal and external - this is wished to occur at and select the chassis accordingly. A bar of alloy is "live" in the highs; a laminated slab of wood and lead is "live" in the low frequencies. Then ask yourself what energy appears from what source and at what frequency? > Others are possible. > Vibration *can* be extracted & quelled without > resorting to the use of metal parts, which form "echo > chambers" within the TT structure. That's conjecture, Igor. Thorough, scientific, validated analysis has yet to be performed on any of these concepts. IOW, a "perfect" transmission of energy centered at exactly the mid point of all frequencies emitted by any given arm with regard to level (RIAA) which can then be perfectly damped to critical. This is possible, we just don't know how to do it yet. > As for the > transmittance of low frequency floor-borne noise, the > subject of chassis "Q" tuning considerations in > another post, well, that's what a good air suspension > underneath it all is good for (not that anything will > kill that completely). More on the general subject, > time permitting. > > Igor The concern expressed by another member some time ago is one needing further exposure: *Any* decoupling of relatively heavy parts within the base sandwich and any decoupling of the arm/bearing interface *will* fall prey to some degree to the preponderance of midbass energy (reproduced musical power in a room being centered very roughly above 100 and below 250 Hz) and risks injecting exponentially higher amounts of energy into the system. Once you correct RIAA *and* amplify to 100dB, you *will* be faced with this. Further, and as a entirely separate topic, *any* loss of coupling/sinking/matching at the arm base will impair (to what degree remains debatable) the predominately HF energy present in that assembly from dissipating. Assuming that's a design goal, which it may not actually be. What amazes me is that your comments, Igor, contain such tremendous vocal concern about huge blasts of incredibly delayed energy ricocheting all over our base but never a word about the duress the arm is under. I own a Kuzma Reference Stogi, easily one of the most robust tapered alloy arms in terms of it's ability to deal with energy input by the cartridge - perhaps while this arm *will* couple very well to the heavier base, those planning to use Maywares and Black Widows and Grace 707's *should* indeed plan thin damped bases made of carbon fiber or pressboard. And should play records at lower volumes... Jon Lane Subject: RE: [teres] isodamp; lossy approach is not the best? Date: Thu, 16 Mar 2000 09:06:13 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Daus: Thanks for the analysis. I agree that a high internal damping factor is important for a lossy approach. Your research in that area is valuable and I was pleased to see that MDF has such a good TF. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Daus Studenberg [SMTP:daus@ufl.edu] > Sent: Thursday, March 16, 2000 12:42 AM > To: teres@aiko.com > Subject: Re: [teres] isodamp; lossy approach is not the best? > > 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 > > ----- Original Message ----- > From: > To: > Sent: Wednesday, March 15, 2000 4:23 PM > Subject: Re: [teres] isodamp; lossy approach is not the best? > > > > Regarding the Lossy or rigid argument on the Record, Platter, bearing, > > chassis, arm, and cartridge needle, and back to the record interface > (loop), > > I believe that the trick is to damp as much as possible but do not have > any > > type of slope to do so. Vibrational energy traveling in any material is > going > > to bounce around and do all sorts of nasty stuff that will alter the > original > > waveform. That energy needs to be directed somewhere, where it won't be > > picked up again. The idea of a perfect loop where energy arrives back at > the > > source in sync with the original signal is impossible given the scale of > > structures we are dealing with. But I do agree will Jon and Tom on the > idea > > that we don't won't the arm support moving at different rates then the > > platter/bearing in the audio spectrum. At low frequencies or large > relative > > movements the structure must act as one unit. However, bearing noise > (even > if > > very little) must not be rigidly coupled to the arm board. How do you > achieve > > both goals? > > 1) Make the bearing to plinth support as rigid as practical. > > 2) Design the plinth supports to sink small scale higher frequencies > into > > some structure that can effectively turn this energy into heat. > > 3) Make the arm board massive so that it can not easily be excited into > > vibration modes. > > 4) Rigidly couple the arm board to the plinth so that large scale > movements > > can not effect one without effecting the other. > > 5) Decouple the arm board to the plinth so that as frequencies increase > the > > arm board is more and more decoupled from the plinth. Note that as > > frequencies increase the associated harmonics generated by the > transmitting > > media will increase in number and time distortions will also increase up > to a > > limit. > > 6) I plan to achieve item 5 by having a gasket of sorbothane under the > > armboard and the armboard will be drilled with holes to accept silicon > > tubing, through the tubing I will have SS cap screws that will secure > the > > armboard to the plinth. The tubing will extend slightly beyond the > shoulder > > of the holes in the armboard. This will allow the use of washers on top > of > > the silicon tubing to compress the tubing as the cab screws are > tightened. > As > > the cap screws are tightened not only will the tubing be compressed, but > so > > will the sorbothane gasket. I plan on using at least 4 compression > assemblies > > for the arm board. All holes will be counter sunk so that the cap screw > heads > > will not extend above the top surface of the armboard. I think this will > > allow me to effectively tune the decoupling of the arm board to achieve > the > > best of both worlds. A rigid interface that will not transmit mechanical > > noise, but instead sink the energy to minimize noise pick up by the > cartridge > > other than what it tracks. Subject: RE: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 09:16:33 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Igor has articulated my beliefs very succinctly and his description below is very close to how I plan on doing my base. He has saved me the effort of saying very similar things. There have been a number of intelligent and detailed arguements for both the lossy and the rigid & ringy camps. Earlier I told Jon that I would have to think more before I could disagree with his compelling arguement; I now have thought it through and decided I don't agree with his techniques. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Igor Kuznetsoff [SMTP:gorkuz@yahoo.com] > Sent: Thursday, March 16, 2000 3:37 AM > To: teres@aiko.com > Subject: Re: [teres] isodamp; lossy approach is the best? > > Thank you Daus, and welcome back. I've been trying to > say something much like this to the "rigid & ringy" > chassis camp, but haven't had the time to explain my > viewpoint very well. If I remember correctly, and > also for the benefit of those recent to our group, you > are a formal student of acoustics, correct? My > viewpoint is that the best materials should be rigid > *and* lossy, not rigid vs. lossy, and certainly *not* > flexible/deformable. I believe that "lowly" MDF is > indeed an *excellent* material for the purpose, > especially if augmented with something like a wrap of > even more rigid/ internally well damped carbon > fiber/epoxy, using MDF/lead/MDF or MDF/Isodamp/MDF > as an actively desirable, inexpensive, practically > workable spacer core. This is far better than using a > highly transmissive material, like metal, to form a > "perfect loop" between the arm and platter, damped or > not. It takes *time* for vibration to travel, so it > simply cannot magically appear "everywhere at the same > time", as in Jon's conception, as that is patently > **impossible**. Fixing that relationship rigidly for > stability, so that everything stays "put" relatively > (or "moves together", if you like), is critical, but > that should be done with a material which can > "extract" the vibration, and kill it, not pass it on > happily back and forth between the arm & platter. > When a platter/chassis/arm/cartridge circuit is formed > with a highly transmissive material like the > frequently proposed Stainless Steel, vibrational > energy will, as observed below, "bounce around and do > all sorts of nasty stuff", ending up back at the > stylus, of course. There is also an old engineering > term to cover some aspects of that condition - > "feedback loop". Sinking vibration from those parts > can be accomplished *without* linking them with a > "live" connection, or using more than a minimum of, if > any, "ringing" materials, as I suggested in a possible > configuration yesterday. Others are possible. > Vibration *can* be extracted & quelled without > resorting to the use of metal parts, which form "echo > chambers" within the TT structure. As for the > transmittance of low frequency floor-borne noise, the > subject of chassis "Q" tuning considerations in > another post, well, that's what a good air suspension > underneath it all is good for (not that anything will > kill that completely). More on the general subject, > time permitting. > > Igor > > > --- Daus Studenberg wrote: > > 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 > > > > ----- Original Message ----- > > From: > > To: > > Sent: Wednesday, March 15, 2000 4:23 PM > > Subject: Re: [teres] isodamp; lossy approach is not > > the best? > > > > > > > Regarding the Lossy or rigid argument on the > > Record, Platter, bearing, > > > chassis, arm, and cartridge needle, and back to > > the record interface > > (loop), > > > I believe that the trick is to damp as much as > > possible but do not have > > any > > > type of slope to do so. Vibrational energy > > traveling in any material is > > going > > > to bounce around and do all sorts of nasty stuff > > that will alter the > > original > > > waveform. That energy needs to be directed > > somewhere, where it won't be > > > picked up again. The idea of a perfect loop where > > energy arrives back at > > the > > > source in sync with the original signal is > > impossible given the scale of > > > structures we are dealing with. But I do agree > > will Jon and Tom on the > > idea > > > that we don't won't the arm support moving at > > different rates then the > > > platter/bearing in the audio spectrum. At low > > frequencies or large > > relative > > > movements the structure must act as one unit. > > However, bearing noise (even > > if > > > very little) must not be rigidly coupled to the > > arm board. How do you > > achieve > > > both goals? > > > 1) Make the bearing to plinth support as rigid as > > practical. > > > 2) Design the plinth supports to sink small scale > > higher frequencies into > > > some structure that can effectively turn this > > energy into heat. > > > 3) Make the arm board massive so that it can not > > easily be excited into > > > vibration modes. > > > 4) Rigidly couple the arm board to the plinth so > > that large scale > > movements > > > can not effect one without effecting the other. > > > 5) Decouple the arm board to the plinth so that as > > frequencies increase > > the > > > arm board is more and more decoupled from the > > plinth. Note that as > > > frequencies increase the associated harmonics > > generated by the > > transmitting > > > media will increase in number and time distortions > > will also increase up > > to a > > > limit. > > > 6) I plan to achieve item 5 by having a gasket of > > sorbothane under the > > > armboard and the armboard will be drilled with > > holes to accept silicon > > > tubing, through the tubing I will have SS cap > > screws that will secure the > > > armboard to the plinth. The tubing will extend > > slightly beyond the > > shoulder > > > of the holes in the armboard. This will allow the > > use of washers on top of > > > the silicon tubing to compress the tubing as the > > cab screws are tightened. > > As > > > the cap screws are tightened not only will the > > tubing be compressed, but > > so > > > will the sorbothane gasket. I plan on using at > > least 4 compression > > assemblies > > > for the arm board. All holes will be counter sunk > > so that the cap screw > > heads > > > will not extend above the top surface of the > > armboard. I think this will > > > allow me to effectively tune the decoupling of the > > arm board to achieve > > the > > > best of both worlds. A rigid interface that will > > not transmit mechanical > > > noise, but instead sink the energy to minimize > > noise pick up by the > > cartridge > > > other than what it tracks. > > > > > > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 09:49:08 -0700 From: Zack Winestine, Zack Winestine To: teres@aiko.com On Thu, 16 Mar 2000, Steve Zettel wrote: > > The Corian (or MDF, or acrylic) will be 3/4" or 1", the steel or aluminum > not thicker than 1/4". However, Nick makes the point that Corian by itself > is quite stiff and non-bendable. FWIW, the Townshend table uses a 1/8" steel plinth (coated with some substance claimed to have anti-resonant properties) with MDF bonded to the bottom and 1/2" acrylic bonded to the front top half of the plinth. The whole plinth rests on an air bladder (innertube) which is in turn supported by an MDF chassis. Results in my difficult space have been very satisfactory -- the 'table is in a corner just two feet to the side of one of my speakers, everything supported by a suspended wood floor. No problems with footfalls, and no apparent problems with acoustical feedback (although the background noise level in my NYC apartment may be high enough to mask some of these problems if they were present). Zack ________________ STATES OF CONTROL soundtrack now available the STATES OF CONTROL site www.statesofcontrol.com Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 09:50:23 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Thu, 16 Mar 2000, Steve Zettel wrote: > The Corian (or MDF, or acrylic) will be 3/4" or 1", the steel or aluminum > not thicker than 1/4". However, Nick makes the point that Corian by itself > is quite stiff and non-bendable. True but it has some strange resonant characters which demand lamination. I used 5/16" aluminum with 1/8" lead in between for my plinth. Kal Subject: [teres] Strobo disc Date: Thu, 16 Mar 2000 09:56:58 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Dear list members, Now that that the design of the motor controller is mostly done we need to talk about the strobe disc. This disc has an outer diameter of about 145mm and is divided into 54 black and 54 white fields. It has to be attached to the back side of the platter. A small reflective interrupter is mounted to the plinth in a way that the distance between the sensor and the strobe disc is about 1mm. The sensor is connected to the controller by a wire with three conductors. For the sensor to work correctly the black fields of the strobe disc have to absorb IR light while the white fields have to be reflective. The sensor is not focussed so we do not need a mirror surface. The output signal of the sensor looks more like a sine wave than a square wave. An analog comparator on the controller board shapes the output of the sensor into a rectangular form which can be applied to the CPU. After some try and error I found out that the toner material used in laser printers absorbs IR light very well. The contrast of the toner and normal white paper is enough to give a 1:10 current ratio at the output of the sensor. There are two different control algorithms running on the controller. The first is 'fast' reacting and relies on the period of the signal coming from the sensor. This algorithm is used to bring the platter up to nominal speed at startup. The second algo. is very slow and does not rely on the period of the sensor signal but instead it simply counts impulses. This algo. is used during normal operation. The fast algo. relies on the precision of the strobe disc but fortunately it is only used during startup and we don't care much about the quality of control during that phase. The slow algo. which is vital for the performance of the control unit doesn't care too much about the geometric precision of the strobe disc. This scheme allows us to get away with a fairly simple interrupter device and strobe disc. Here is how I implemented the strobe disc: First I used a CAD program to create an image of the strobe disc (STROBO.TIF). The .tif has an resolution of 600dpi and when printed on a 600dpi laser printer the result is a strobe disc with an outer diameter of about 147mm. After printing is done the back side of the paper is covered with sticky tape. I used the type of tape that is sticky on both sides. The protective cover on the tape is *not* removed at this point in time. Next I used a compass that is equipped with a scalpel blade to do four circular cuts: 1. d=160mm, cut all way though the disc, tape and cover. 2. d=145mm, cut from the back side through the protective cover, the tape and the paper. The cut through the paper is not done completely so that there is still some connection of the inner and outer part of the disc. 3. d=125mm, cut in the same way as (2) 4. d=diameter of center hole of the platter. Cut all way though the disc, tape and cover. This is gives a hole in the center of the strobe disc that can be used to align the center of the disc and the platter. After cutting is done a ring of protective cover between cut 2 and 3 is removed. The remaining cover is not removed! Now the disc is centered on the back side of the platter and the sticky tape is pressed on. Do not rub! You don't want to remover the toner! Now all material on the inside of cut #3 and on the outside of cut #4 can be removed. All that remains on the platter is a ring with an inner diameter of 125mm and an outer diameter of 145mm. Recently I noticed that there is a white plastic foil on the market that is sticky on one side and can be used with a laser printer. This can simplify the whole procedure quite a bit. Maybe there is someone on the list who is working in the printing/publishing business and can help us with the strobe disks? Any ideas to simplify the process are welcome. Please excuse the language used in this article but it is very hard for me to describe such a complicated task in english. Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: RE: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 10:00:00 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Sorry, Jon. Choose your reference frame: Newtonian Physics, Relativistic Physics, or Quantum Physics; perfection is not possible. That's the flaw that invalidates your whole arguement. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Jon Lane [SMTP:jhlane@email.msn.com] > Sent: Thursday, March 16, 2000 7:49 AM > To: teres@aiko.com > Subject: RE: [teres] isodamp; lossy approach is the best? > Jon Lane said: " IOW, a "perfect" transmission of energy centered at exactly > the mid point of all frequencies emitted by any given arm > with regard to level (RIAA) which can then be perfectly > damped to critical. This is possible, we just don't know > how to do it yet." > Subject: [teres] lossy and rigid materials Date: Thu, 16 Mar 2000 10:24:50 -0700 From: daus@ufl.edu, daus@ufl.edu To: teres@aiko.com Hi everyone, I found out that "super matereial" that I saw in my vibrations class. It is manufatured from EAR specialty composites and is labeled CN-62. Yes, this an an ISODAMP material. I understand that some people are ordering the sheet, but this is a .5" thick tile. It is also quite strong like plexiglass. I love the 4.50lb/sqft spec!! Another material I found was c- 1002. This is 1" thick and I believe a solid vinyl and like 6.50 lbs/sqft! I will look into this a little more when I have some more time. The other company that made the some similar stuff that I knew was "Sounddown". Daus Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 11:33:37 -0700 From: David Dlugos, David Dlugos To: teres@aiko.com >On Thu, 16 Mar 2000, Zack Winestine wrote: > >> Incidentally, does anyone know of a site anywhere with a Mac program for >> printing a 60hz (33 1/3) strobe disc? > >How about an editable post-script file? Given the dimensional requirements (ie a spec) it would be easy to draw something up in Illustrater or VectorWorks and generate a pdf file so anyone could use it. I have all these tools so i guess i could be put on the short list of volenteers. dave __________________ Transmission Line Speaker Page http://www.t-linespeakers.org/ Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 11:33:46 -0700 From: David Dlugos, David Dlugos To: teres@aiko.com >It would be nice if we could figure out a way >to print the disc on plastic rather than paper (which might yellow or >abosorb moister and wrinkle). My local copy shop offers laser printing >onto clear plastic sheets (for overhead transparencies) but I don't know >if a white option might be availale. I will check. > >Incidentally, does anyone know of a site anywhere with a Mac program for >printing a 60hz (33 1/3) strobe disc? > Given the dimensional requirements (ie a spec) it would be easy to draw something up in Illustrater or VectorWorks and generate a pdf file so anyone could use it. I have all these tools so i guess i could be put on the short list of volenteers. To get the strobe on plastic, just take the file (or mail it to) a service bureau and get it output on the "linotype" as a positive on film stock. Black on clear is the only option here thou. inkjets & laserwriters can output onto transparency film. I don't know wether the inks would be opaque enuff thou and dimensional accuracy is not as good as on a properly calibrated "lino" dave __________________ Transmission Line Speaker Page http://www.t-linespeakers.org/ Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 11:59:17 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com > >On Thu, 16 Mar 2000, Zack Winestine wrote: > > > >> Incidentally, does anyone know of a site anywhere with a Mac program for > >> printing a 60hz (33 1/3) strobe disc? Here's a simple eps script which will do 3 speeds at 60hz. I have edited if for other applications including the generation of a 600line/revolution disc. Kal --------------------------------------------------------------------- Name: 60hz.eps 60hz.eps Type: Postscript Document (application/postscript) Encoding: base64 Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 12:03:17 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com All, Steve expresses my feelings concisely. All anecdotal data is certainly appreciated, even if we end up with our "own" design. One thing is certain - that the shape of my base will not be overly complex, and like Steve's will probably take on an industrial art look rather than "drawing room" look. This should be easier to produce and re-produce (out of different materials). Cheers, Thom ----- Original Message ----- From: Steve Zettel Sent: Thursday, March 16, 2000 10:47 AM Subject: Re: [teres] isodamp And thank you, Kal, for more data. I appreciate the help zeroing in on the design. I was afraid I would be siting here next year with a platter/bearing kit and motor/controller kit, but be paralyzed by chassis and plinth concerns! Steve Z __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 12:07:55 -0700 From: Jeremy Epstein, Jeremy Epstein To: teres@aiko.com > on 3/16/00 08:48, Zack Winestine at impulse@echonyc.com wrote: > > Results in my difficult space have been very > > satisfactory -- the 'table is in a corner just two feet to the side of one > > of my speakers, everything supported by a suspended wood floor. No > > problems with footfalls, and no apparent problems with acoustical feedback > > (although the background noise level in my NYC apartment may be high > > enough to mask some of these problems if they were present). I have a similar layout and I am using a shelf mounted to the wall - I wasn't able to kill the shock from footsteps any other way, I was getting skipping, never mind noise. What is under your 'table? -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: Re: [teres] isodamp - off topic : skis Date: Thu, 16 Mar 2000 12:10:14 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Hexcellant idea Steve, I got some old 165cm hexcels that are pretty beat up and too short now that I can ski good, at least for a Texan. Sounds like this could start a recycling program, that is if they sound as good as they ski. Time to hack the Hexcel's. Stan At 08:58 AM 3/16/2000 -0500, Jeremy Epstein wrote: >Steve Zettel wrote: > >> One or two rigid sheets of aluminum or steel, sandwiching a core of inert >> foam or honeycomb (like the old Hexcel skis) might be one configuration. > >Finally a subject on which I can speak with authority. > >My 80's Hexcel Super Comps were, by a wide margin and without a shadow >of a doubt, the finest skis I have ever had the pleasure to use. The >shovel (front 1/3 to the non-skiers on the list) was so quick and >responsive that, despite running 195 cm skis, I was able to turn on a >dime as if I was on 175 cm slalom skis, and the tails were so stiff and >well damped that I was able to laugh at ice, even with >less-than-perfectly tuned edges (yes, Thom and Igor, ice is a feature of >skiing, at least the Vermont kind.) They ran amazingly stable and fast >on the flats and were simple to carve smooth turns with - truly a ski >without compromises. I miss them. > >The K2's I will be trotting out for next week's trip to Smuggler's Notch >just give me nostalgia for the Hexcels. Boy, would I love to find a >warehouse full of NOS Hexcels! > >-j >-- >========================================= >Jeremy Epstein .........jepstein@shwd.com >========================================= > Subject: [teres] "Tiptoes" an alternative Date: Thu, 16 Mar 2000 12:14:47 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com One thought that just struck me (this a tip from Pierre Sprey of Mapleshade) -- instead of using a cone as a tiptoe support, brass acorn nuts work just as well for point contact on hard surfaces, are readily available, and are much cheaper (not a specially fabricated, low volume, "audiophile" item). They are already tapped and threaded, so could readily be used as both feet on the bottom of a subchassis, and as the securing nut on the end of a properly sized through bolt. Don't thank me, thank Pierre (buy some of his excellent CDs!) Steve Z Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 12:26:26 -0700 From: David Dlugos, David Dlugos To: teres@aiko.com >> >On Thu, 16 Mar 2000, Zack Winestine wrote: >> > >> >> Incidentally, does anyone know of a site anywhere with a Mac program for >> >> printing a 60hz (33 1/3) strobe disc? > >Here's a simple eps script which will do 3 speeds at >60hz. I have edited if for other applications including >the generation of a 600line/revolution disc. Here is the file converted to a pdf. dave --------------------------------------------------------------------- Name: 60hz_strobe.pdf 60hz_strobe.pdf Type: Portable Document Format (application/pdf) Encoding: base64 Name: ATT00060.txt ATT00060.txt Type: Plain Text (text/plain) Encoding: base64 Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 12:46:23 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Thu, 16 Mar 2000, David Dlugos wrote: > >Here's a simple eps script which will do 3 speeds at > >60hz. I have edited if for other applications including > >the generation of a 600line/revolution disc. > > Here is the file converted to a pdf. Note that one can edit the file by 1. deleting unnecessary lines (other speeds) 2. changing line thickness 3. changing line length 4. changing number of lines Very flexible. Kal Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 12:47:24 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Thu, 16 Mar 2000, Steve Zettel wrote: > I responded in the affirmative that an .eps file would work with a Mac. I > was thinking .pdf, which any version of Adobe Acrobat Reader would open. > Sorry for the brain bubble. EPS should work just fine, too, if I can figure > out which Mac program I can use to open and edit it, how to send it to the > printer. . . The eps file can be opened and edited as ordinary text. Kal Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 12:48:16 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com Looking back at Manfred's post, the key items that pop out at me are: > This disc has an outer diameter of about 145mm and is divided into 54 black > and 54 white fields. It has to be attached to the back side of the platter. A > small reflective interrupter is mounted to the plinth in a way that the > distance between the sensor and the strobe disc is about 1mm. The sensor is > connected to the controller by a wire with three conductors. > And: > First I used a CAD program to create an image of the strobe disc (STROBO.TIF). > The .tif has an resolution of 600dpi and when printed on a 600dpi laser > printer the result is a strobe disc with an outer diameter of about 147mm. > The existing strobe pattern via Kal and David doesn't quite meet this criteria, but it should be possible to use Manfred's .tif file regardless of platform. >From Manfred's explanation of how the timing signals are used, during running the sensor/circuit is counting pulses, so as long as there are 54 light and dark pulses it should function OK, even with a diameter smaller than 145mm. For start up, reducing the strobe diameter to recess the works in from the edge of the platter, may be more problematical. Steve Z Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 12:59:07 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Thu, 16 Mar 2000, Steve Zettel wrote: > The existing strobe pattern via Kal and David doesn't quite meet this > criteria, but it should be possible to use Manfred's .tif file regardless of > platform. It requires editing. Here's an edited version for 600 lines. Kal --------------------------------------------------------------------- Name: 600.eps 600.eps Type: Postscript Document (application/postscript) Encoding: base64 Subject: Re: [teres] "Tiptoes" an alternative Date: Thu, 16 Mar 2000 13:52:29 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com As much as I like a cheapskate solution, beware that all cones do not "sound" alike. Cap nuts may be just fine in some applications. Go back and read Gordon's excellent post from last week on (his understanding of) how tip toes do their thing. It was a response to a fuzzy comment I made where I noted that many contend that tip toes are the mechanical analog of a diode. Certainly from the viewpoint of concentrating the point of contact on a flat surface, cap nuts will do the job. I'll certainy give them a try to see how they compare to my (a) garden variety aluminum jobbies (b) a set of Simply Physics cones (c) a set of Black Diamond Racing cones. The Black Diamonds did nice things for my BAT preamp on a triple layer MDF surface. On Chris' Loesch preamp, all of us thought the aluminum ones were superior to both the BDR's and various inflation levels of the inner tube. Moral of the story - we're tortured souls and are forever doomed to experimentation :>)) Cheers, Thom ----- Original Message ----- From: Jeremy Epstein To: Sent: Thursday, March 16, 2000 12:17 PM Subject: Re: [teres] "Tiptoes" an alternative Any hardware store will have acorn nuts, also called cap nuts, in various sizes. They are like any regular nut except they are closed on one side with a round "cap." This round side will make point contact if the nut gets used as a foot. -j Alex Mitaru wrote: > > At 11:13 AM 3/16/00 -0700, you wrote: > >Steve Zettel > >-- instead of using a cone as a tiptoe support, brass acorn nuts work just > >as well for point contact on hard surfaces, are readily available, and are > >much cheaper (not a specially fabricated, low volume, "audiophile" item). > > sorry, but what are these and where does one buy them? > > thanks, alex > > ____________________________________________________________________ > Alexandru Mitaru alexmi@omneon.com > System Architect (503) 533-0621 ext 228 > Omneon Video Networks (503) 533-5811 FAX -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 14:19:55 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > Sorry, Jon. Choose your reference frame: > Newtonian Physics, Relativistic > Physics, or Quantum Physics; perfection is not > possible. That's the flaw > that invalidates your whole argument. What is? I'm genuinely anxious to hear your analysis. Of *course* perfection is not possible; the question has always been couched in variables: mass, tuning, transmission, etc. I'm sorry to rub up against your chosen politics, Ken, but despite your vagueness (and my informality), I still ask you to explain specifically how a device cannot be designed to allow frequency selective input...you're the engineer. Jon Lane Subject: Re: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 16:00:31 -0700 From: Doug Kelly, Doug Kelly To: teres@aiko.com > > Sorry, Jon. Choose your reference frame: > > Newtonian Physics, Relativistic > > Physics, or Quantum Physics; perfection is not > > possible. That's the flaw > > that invalidates your whole argument. > > What is? I'm genuinely anxious to hear your analysis. > > Of *course* perfection is not possible; the question has > always been couched in variables: mass, tuning, > transmission, etc. > > I'm sorry to rub up against your chosen politics, Ken, but > despite your vagueness (and my informality), I still ask you > to explain specifically how a device cannot be designed to > allow frequency selective input...you're the engineer. > > Jon Lane I may be jumping in out of place here, but I'll give it a shot. Jon, I don't think anyone is arguing with the notion of selective damping of transmission at the tonearm junction - I think what most people are taking issue with is the notion of a 'closed loop' mechanical system. A closed loop system in electrical or control systems is essentially one that employs feedback as a means of minimizing errors (oversimplified, so don't kill me). At a high-level, handwaving perspective, this looks great as applied to turntables - make sure that the bearing and tonearm form a 'closed loop' system, so that everything vibrates together in-phase, so that there is no differential motion. The problem, as people have argued, is that vibration doesn't really work that way, and that such a feedback loop can't possibly reduce vibration-induced distortion in a turntable. Now, your other point, which appears to be the one that you are more closely attached to, is really one of how best to sink vibration away from the tonearm. Here, I think there is less objection, but I don't want to put words in anyones moutn. Fundamentally, your intention to measure the results as much as possible is the right direction. However, having done some measurement of something as relatively well-defined as speaker frequency response, I know this isn't going to be easy. I've been intending to perform similar measurements to test isolation and damping as well, although I'm not entirely sure how. I have a couple piezo disks around which certainly produce a signal when placed on a shelf and the shelf is tapped, but whether they produce anything that can be anaylysed is another question. I have LAUD, and so it's occured to me that by placing a raw driver in mechanical contact with a test material and then measuring the response of the piezo you can get a 'frequency response' for transmitted energy, but I'm rather dubious that this will produce much. Before signing off, I'll throw another $0.02 thought into the damping fray, though perhaps I shouldn't. The question of sinking vibrational energy at the tonearm base is interesting, and I don't disagree with it, but I'm having difficulty relating the importance that people are placing on it with the apparent success of air-bearing arms. It looks like no air-bearing is really 'state of the art' at this point, but even the ET2 stands up very well against most competition. Now, given the lack of mechanical contact with anything, it would appear the the ET has no way to 'sink' vibration, and so must rely almost completely on internal damping. Given the enthusiasm with people are attacking the vibration sinking problem, this leaves me at a loss - either - the ET is significantly better damped than conventional arms. This would surprise me somewhat, as it _must_ be lighter than conventional arms due to the lack of a pivot, and so conventional arms could simply incorporate the same damping mechanisms - more energy is 'sunk' through the air layer into the manifold than I think. - this 'problem' isn't as big as it seems - ??something else - resonant structure is 'euphonic' - arm really isn't as good as I think it is.... Given my use of an air-bearing on the platter, I went through similar thought patterns here as well, but it doesn't take much to get to the point where I feel that it's not an issue - the platter itself needs to be internally damped to a high degree, and so I don't think 'sinking' energy via the bearing is critical. This is indeed a different case than conventional bearings, though, as there is no bearing noise to be concerned about - I would think you _do_ need to be conderned about 'sinking' this bearing noise in a conventional bearing. Doug Kelly kdouglas1@uswest.net Subject: RE: [teres] isodamp; lossy approach is the best? Date: Thu, 16 Mar 2000 17:13:05 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Jon: I'm glad to hear you agree that perfection is impossible because the wording of your prior statement and others before that read as if you believed it was. I'm not saying your method won't work, only your explanation. If you say "nearly perfect" instead of "perfect" and "almost instantaneous transmission of enegy" instead of "instantaneous transmission of energy" then your explanation becomes theoretically plausible. And a device certainly can be designed to allow frequency selective input - I have no arguement with that. The reason I'm so fastidious about the wording is because your explanation demands a level of near-perfection and near-instantaneous transmission of energy that I have doubts about achieving. To say "perfect" and "instantaneous" glosses those problems over. Igor eloquently described a good lossy system and I won't waste bandwidth repeating the same things. One reason I favor a lossy system rather than your system is because the lossy system doesn't demand those near-perfect qualities and near-instantaneous transmissions of energy. Cheers, Ken > -----Original Message----- > From: Jon Lane [SMTP:jhlane@email.msn.com] > Sent: Thursday, March 16, 2000 1:15 PM > To: teres@aiko.com > Subject: RE: [teres] isodamp; lossy approach is the best? > > > > Sorry, Jon. Choose your reference frame: > > Newtonian Physics, Relativistic > > Physics, or Quantum Physics; perfection is not > > possible. That's the flaw > > that invalidates your whole argument. > > What is? I'm genuinely anxious to hear your analysis. > > Of *course* perfection is not possible; the question has > always been couched in variables: mass, tuning, > transmission, etc. > > I'm sorry to rub up against your chosen politics, Ken, but > despite your vagueness (and my informality), I still ask you > to explain specifically how a device cannot be designed to > allow frequency selective input...you're the engineer. > > Jon Lane > > Subject: Re: [teres] isodamp Date: Thu, 16 Mar 2000 19:02:13 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com CC: almarj@uswestmail.net In a message dated 3/16/00 12:59:48 PM Mountain Standard Time, phclark@uswest.net writes: << I suspect that there will be enough different implementations that some of the discussion recently won't apply except in the general sense. I'm following it all closely, but barring making *stupid* mistakes, for me I think just forging ahead (with a clear eye) may prove to be the practical answer. Since I am graced with concrete floors, I can only speculate how much the "lossy" aspects will apply to the platter and motor. >> I too have a listening room with concrete floors. I'm building two tables one for suspended floors and one for solid concrete floors. They will both use the same plinth. I am going to build an "X" shaped plint with two inch or greater brass cylinders for the legs that will connect to the end of each arm of the "X". The solid floor model will have the brass legs working as piers into a sandbox. They will be floating above the base of this sandbox using springs. Once the unit is leveled, the sand will flow around the spring pier structure to work as a sink for vibrational energy. The suspended floor model will have air bladders in a large diameter cup. The brass legs will sit on top of the air bladders. The cups will rest on a large base or self probably made out of some constrained laminated dampening materials such as corian, massonite, hardwood, etc. The cups will also allow the option of filling with silicon dampning fluid. Firestone makes some excellent air bladders but I have not yet found a price out. Here is the web address if anyone is interested. http://www.firestoneindustrial.com/microact.htm until again, Gordon Subject: Re: [teres] lossy and rigid materials Date: Thu, 16 Mar 2000 19:10:55 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com Possibly, I only looked at the labels and that was the name on one of them. I will check later on, their stuff that was of interest was the equivalent of CN-62 in 1/4" thickness. Daus BTW, you asked about what I was studying and it is in mechanical engineering. I am unfortunately taking the ONLY acoustics class offered here this semester. :( ----- Original Message ----- From: Igor Kuznetsoff To: Sent: Thursday, March 16, 2000 12:08 PM Subject: Re: [teres] lossy and rigid materials > Daus, > Would this be Soundown at 17 lime St, > Marblehead, > Mass., 01945 , # 617-631-9611 ? > Subject: [teres] Have to run now... Date: Thu, 16 Mar 2000 20:28:40 -0700 From: Jon Lane, Jon Lane To: Teres@Aiko.Com Dear Gentlemen, With all of our Teres platters within sight, and with Manfred’s heroic efforts providing the best possible motivation with which to turn them, now feels right to thank the players for their insight and dedication. Teres is undoubtedly one of the most notable DIY projects to ever grace an audiophile’s system, and I’m certain we’re all anticipating making a tremendous performance upgrade, regardless of our individual final designs. Hats off to Chris for his leadership, and also to Thom, Bryce, Ken, Igor and the others who have so generously offered the opportunity of the year, if not the decade. And thanks too, to the spirited participants in our discussions of the remaining elements like chassis, bases, and isolation methods. While I think lack of a formal analysis has us arriving at an impasse concerning at least one of these, it appears nobody need be overly concerned with not realizing excellent performance. The combination of talents present here cannot fail to achieve a variety of subtly differing but still extraordinary results. My schedule makes my further participation nearly impossible, and I find I must concentrate on other things. I think I've been reasonable, if vocal, and failing a formal background, have endeavored to present my notions with an ability to be corrected. At times, we've seen the usual “not invented here” comments and occasionally the personal remark, but on balance, its been a blast. Thanks to all. And to Thom, a special thanks and recognition for possessing what I’ve feel is the finest balance. Thom, your passionate enthusiasm, like mine, has brought you here, and your common sense and civility has allowed you a certain grace through it all. Remarkable stuff. “I think we're all fighting that obsessive tendency - sometimes more successfully than other times.” You’re right, as usual, Thom. Thanks for bring it all back to earth. Best to all, Jon Lane Subject: Re: [teres] Strobo disc Date: Thu, 16 Mar 2000 23:16:57 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 3/16/00 18:50, Daus Studenberg at daus@ufl.edu wrote: > I think it would be best of we could find an adhesive backed paper similar > to the Avery printing labels, but without the label cutouts. Just a plain > white matte sheet would do. Now I think about it, I think a sheet of white > matte vinyl used for window signs might work. Does anyone know how well the > toner sticks to vinyl...if it does at all??? > Daus > > http://www.3m.com/market/graphicarts/imagegraphics/press/archive/ISA/IJPoste rPaper.html 3M restickable ink-jet poster paper http://www.3M.com/us/graphicarts/ 3M graphics arts supplies website http://www.3m.com/profile/pressbox/thermal.html 3M durable outdoor use adhesive back thermal ink-jet paper My suggestion would be that we contact a professional copy/print outfit in some large metro area and tell them exactly what we want; we can even provide them the .eps or other suitable file, or one finished, full size strobe disc, black on white paper, to use as a copy. I'd volunteer, but Libby, MT at 2,800 people (when everybody comes to town) doesn't support even one full-service print place. Steve Z near Libby, MT Subject: Re: [teres] Strobo disc Date: Fri, 17 Mar 2000 00:37:13 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Worst case, we use a little spray contact cement, and mount *anything* at all that we like. Igor --- Steve Zettel wrote: > on 3/16/00 18:50, Daus Studenberg at daus@ufl.edu > wrote: > > > I think it would be best of we could find an > adhesive backed paper similar > > to the Avery printing labels, but without the > label cutouts. Just a plain > > white matte sheet would do. Now I think about it, > I think a sheet of white > > matte vinyl used for window signs might work. > Does anyone know how well the > > toner sticks to vinyl...if it does at all??? > > Daus > > > > > http://www.3m.com/market/graphicarts/imagegraphics/press/archive/ISA/IJPoste > rPaper.html 3M restickable ink-jet poster paper > > http://www.3M.com/us/graphicarts/ 3M graphics > arts supplies website > > http://www.3m.com/profile/pressbox/thermal.html 3M > durable outdoor use > adhesive back thermal ink-jet paper > > My suggestion would be that we contact a > professional copy/print outfit in > some large metro area and tell them exactly what we > want; we can even > provide them the .eps or other suitable file, or one > finished, full size > strobe disc, black on white paper, to use as a copy. > > I'd volunteer, but Libby, MT at 2,800 people (when > everybody comes to town) > doesn't support even one full-service print place. > > Steve Z > near Libby, MT > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Strobo disc Date: Fri, 17 Mar 2000 01:07:27 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com If it doesn't, a fixatif or clear plastic spray could be used over plain/sticky backed/plain paper, or, perhaps better, heavier stock photo paper, like the fairly common 65 lb. either glossy or flat stuff. I just wonder about how long the sticky backed stuff will stay stuck to the *underside* of the platter. Avery type labels, after a few years, tend to dry out and fall off, I've noticed. Maybe some spray contact cement would be more reliable, if perhaps a little too permanent, should changes be desired. Perhaps the best option would be to use double-sticky-sided CN12 plus the heavy photo paper. Do two things at once. Igor --- Daus Studenberg wrote: > I think it would be best of we could find an > adhesive backed paper similar > to the Avery printing labels, but without the label > cutouts. Just a plain > white matte sheet would do. Now I think about it, I > think a sheet of white > matte vinyl used for window signs might work. Does > anyone know how well the > toner sticks to vinyl...if it does at all??? > Daus > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] isodamp Date: Fri, 17 Mar 2000 01:16:37 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Gordon, I've tried adding silicon damping fluid to the *inside* of my inner tubes by removing the valve, injecting it, and replacing the valve. The tube works better than ever after I smush the fluid around to coat the inside surfaces. I had only a fairly thin fluid to try, and even that seemed to work, but I suspect that the thicker that is, the more effective it would be. Igor --- MaughanAudio@aol.com wrote: > In a message dated 3/16/00 12:59:48 PM Mountain > Standard Time, > phclark@uswest.net writes: > > << I suspect that there will be enough different > implementations that some of > the discussion recently won't apply except in the > general sense. I'm > following it all closely, but barring making > *stupid* mistakes, for me I > think just forging ahead (with a clear eye) may > prove to be the practical > answer. Since I am graced with concrete floors, I > can only speculate how > much the "lossy" aspects will apply to the platter > and motor. >> > > I too have a listening room with concrete floors. > I'm building two tables one > for suspended floors and one for solid concrete > floors. They will both use > the same plinth. I am going to build an "X" shaped > plint with two inch or > greater brass cylinders for the legs that will > connect to the end of each arm > of the "X". The solid floor model will have the > brass legs working as piers > into a sandbox. They will be floating above the base > of this sandbox using > springs. Once the unit is leveled, the sand will > flow around the spring pier > structure to work as a sink for vibrational energy. > > The suspended floor model will have air bladders in > a large diameter cup. The > brass legs will sit on top of the air bladders. The > cups will rest on a large > base or self probably made out of some constrained > laminated dampening > materials such as corian, massonite, hardwood, etc. > The cups will also allow > the option of filling with silicon dampning fluid. > Firestone makes some > excellent air bladders but I have not yet found a > price out. Here is the web > address if anyone is interested. > http://www.firestoneindustrial.com/microact.htm > > until again, Gordon > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] isodamp Date: Fri, 17 Mar 2000 01:23:23 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Just looked at the site, thanks. Their mini air spring looks like an interesting way to suspend a sandbox. Holler if you hear prices. Igor --- MaughanAudio@aol.com wrote: > In a message dated 3/16/00 12:59:48 PM Mountain > Standard Time, > phclark@uswest.net writes: > > << I suspect that there will be enough different > implementations that some of > the discussion recently won't apply except in the > general sense. I'm > following it all closely, but barring making > *stupid* mistakes, for me I > think just forging ahead (with a clear eye) may > prove to be the practical > answer. Since I am graced with concrete floors, I > can only speculate how > much the "lossy" aspects will apply to the platter > and motor. >> > > I too have a listening room with concrete floors. > I'm building two tables one > for suspended floors and one for solid concrete > floors. They will both use > the same plinth. I am going to build an "X" shaped > plint with two inch or > greater brass cylinders for the legs that will > connect to the end of each arm > of the "X". The solid floor model will have the > brass legs working as piers > into a sandbox. They will be floating above the base > of this sandbox using > springs. Once the unit is leveled, the sand will > flow around the spring pier > structure to work as a sink for vibrational energy. > > The suspended floor model will have air bladders in > a large diameter cup. The > brass legs will sit on top of the air bladders. The > cups will rest on a large > base or self probably made out of some constrained > laminated dampening > materials such as corian, massonite, hardwood, etc. > The cups will also allow > the option of filling with silicon dampning fluid. > Firestone makes some > excellent air bladders but I have not yet found a > price out. Here is the web > address if anyone is interested. > http://www.firestoneindustrial.com/microact.htm > > until again, Gordon > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Chassis impedance Date: Fri, 17 Mar 2000 02:53:03 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Folks, Some further notes came to mind concerning part of a previous post, tacked on below for reference, that I would like to add. Notes follow below. The excerpt: A "hybrid" structure keeps surfacing in my thoughts lately. Using a tapered metal plate, with the large end drilled for, and attached to the structure we want to sink vibrations *from* (just like a heat sink), a rigid structure can be formed by embedding this plate in something else that is very rigid, but lossy, like, say, a carbon fiber/epoxy composite. The tapered end (to a point possibly) would not contact any other metal. The taper would discourage standing waves within the metal piece, just as the taper in a TL would, and progressively terminate the metal/other material interface. Let's say that the arm is mounted in this piece. From the other end, a similar detail is built, mounting the bearing, say. The two metal plates never contact. They can be spiked with 'toes to sink them individually to the (hopefully lossy) surface underneath, if desired. This prevents direct transmission from one to the other, reducing the formation of a feedback/transmissive loop, while providing the rigid coupling necessary for fixing the arm/platter relationship stably, and avoiding the modulation noise which could occur if this were not so. In my rush to dash this off, I left off: The metal plates would not only act as "vibration sinks", but also as *impedance matching devices* between the parts mounted on them, and the rigid but lossier material they are embedded in. As such, they themselves can be custom matched to the parts in question, something that would be impossible if one were to build, say a metal based CLD chassis system. The bearing, being brass, can be mounted onto a brass plate, and the arm can be mounted onto an aluminum or other matching metal. The parts can, in this scheme be coupled directly, metal-to metal (and same to cones, if used), to improve noise transmission, reducing the acoustical impedance reflection that inevitably occurs at all junctions & discontinuities of *any* type, as Steve pointed out, I believe (even with similar materials). This problem becomes far worse when *different* materials are coupled. In this manner, and by employing a diminishing taper to progressively terminate the "sink" area to the remainder of the structure, the transmissive impedances of such a structure can be more smoothly matched, resulting in less reflection back to either the platter or arm. Igor __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: [teres] extreme TT Date: Fri, 17 Mar 2000 11:04:38 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com Hi guys, Good points Steve, looks like this thick cloud is starting to form some solid structure. I totally agree with your platter/record interface ideas and made similar comments earlier at least about using SS as my first choice for platter, arm board and sub chassis. Again look at the Simon York TT, where different mats are recommended to suite each listeners taste. I believe SS or Al would have provided superior support for different mats. Since we have a acrylic platter and have noticed that many of the very top TT are either all acrylic or all metal for the most part. Is this so that the energy velocity will remain constant for lower reflective energy or in a close loop system where energy arrival times will match and thus cancel at the arm board ? I doubt if most designers really worry much about this aspect, except when they write some techno advertisement and I doubt if we can conclusively demonstrate any technological advantage based on some theory. Ah but there is no one that says we can't try. This impedance mismatch/reflectivity. problem has made me upgrade my vision for a close loop armboard, similar to Simon York. It would have the same basic shape, except with a concave (SS) shape at the top and bottom with flat milled areas for the spindle and armboard. The center would be very thin 1/4" at the spindles only contact area and 3/32" at the armboard. With a thin center this should "except" energy and progress at a constant rate towards the thicker 3/4" outer rim which has channels cut at the periphery to except a piece of CN-38 isodamp around the entire armboard. Just like a speaker cone where the surround absorbs the energy with little reflection. This speaker analogous makes more sense to me than some of the others. Of course the top and bottom would be covered by CN-12 or CN-38, which ever one would conform to the concave shape. And the top & bottom would need a coned shaped piece (6" dia.) to match the contours and provide a flat surface for the subchassis. And the top cone would be tapped so that the two cones and subchassis would bolt together as one piece. Also need a center hole to access the spindle nut. Now the armboard is ready to bolt w/o adhesive to the subchassis using long bolts thru the subchassis. Again similar to Simon York except using CLD SS and about 7" circles. There will be a gap between the cones and thin section of the armboard, because the concave runs the entire length of the armboard. Below the bottom cone this area can be cut to a semicircle shape down the entire subchassis. Just like the Accuton speaker drivers that have this semicircle notch to help breakup standing waves on the cone. Another speaker analogy. This cutout can be filled with a cylinder made from stacked CN-62 . I like this subchassis design because the armboard is better isolated from floor borne vibrations and this is very important because the armboard is designed to except and dissipate energy from the inside, at the spindle and tonearm mounts only. Also a smaller foot print provides immunity to higher modal resonances from the TT platform. There's my .02 cents Stan At 10:17 PM 3/15/2000 -0700, Steve Zettel wrote: >Hello, all > >Several thoughts occur to me about the various chassis arguments so far: > >The idea of impedance matches is an attractive one, but ultimately fails >because at any discontinuity, even between two identical materials bolted >tightly together there will be some energy reflected back. > >Several people have used the idea of an acrylic platter as a sink for vinyl >vibrations, or made the statement that vinyl and acrylic are well-matched, >impedance wise. Well, maybe more so than aluminum, but I think we discussed >this early on. The only way to ensure a low-impedance junction between the >platter and the record would be to make the platter out of vinyl, and bond >the record tightly to it all over its surface. If the rigid, stiff crowd was >truly carrying their argument through, the bearing, housing, sub or chassis, >armboard, AND the platter would all be made out of SS or AL, ditto the arm. > >(I have tried my experiments again with my two sorbothane mats, the acrylic >mat and the bare aluminum platter now that I have my Clearaudio Sigma pretty >well broken in. Same results as before: the hard acrylic and especially the >bare platter seem artificially bright, but worse, harmonically incorrect. >Ken had talked about the "detail" of the stiff, rigid undamped designs being >an addition of vibrational energy at the cartridge, and I would tend to >agree. But this is perhaps only true of the platter and mats). > >The stiff, undamped argument does not fully address some other phenomena: > >If we could make everything of a piece with perfect impedance-matched >junctions, so no energy is reflected at junctions, there still is some >amount of lag time before a noise impulse or energy spike (or vibration) >travels from it's origin to some other point. You can't have all parts >instantaneously accelerated, and in phase, to boot. If there is no relative >motion between parts, then there is no extraneous signal - all parts are >moving in concert. But who can predict what phase the signal from chassis is >going to be at the end of the tonearm. Or any other point. > > Also, the junction between the surface of all parts and the surrounding >air, is a large impedance mismatch, which reflects most of the energy >reaching this boundary right back in where it continues to ring. And, just >as we find in driver physics, surface area mismatches, instead of smooth >transitions or gently flaring throats in a horn, also reflect a portion of >the energy. A large, stiff piece of metal that resists bending will >definitely transmit energy. The tonearm, no matter how tightly coupled at >the armboard, and no matter what the material, has to be free to move, else >it could not trace the record grooves. This energy will excite the tonearm >at some characteristic frequency and it WILL be free to vibrate (ever see >the whip-style radio antenna on a car or truck start vibrating violently >even though the car body was motionless to the naked eye, as the motor was >revved?). > >The argument was made that high frequency vibrations are short sharp spikes >of high amplitude and short duration, low frequency vibrations are longer in >duration (but for the same amount of energy will be lower in amplitude). Can >we ensure that all vibrations propagated through our material will be so >high (but unfortunately higher in amplitude as well) that they will be above >the ability of the cantilever of the cartridge to respond? Low frequency >(but low amplitude) vibrations are *bad*, because they are stretched out >over time and cause smearing of the sound. But ONLY if they are of high >enough amplitude to be above the threshold to which the cantilever can >respond. Now we are shaking the back end of our cartridge's generator >relative to the cantilever! > >My thought is we want our chassis material rigid enough so that there is no >relative motion between platter, bearing and armboard, inert enough that >vibrational energy is not readily propagated, and damped enough that what >energy *is* propagated is rapidly attenuated below the response threshold of >the cartridge's generator. > >One or two rigid sheets of aluminum or steel, sandwiching a core of inert >foam or honeycomb (like the old Hexcel skis) might be one configuration. >Carbon fiber might be another. So might a flat sheet of acrylic sandwiched >or at least backed by a sheet of steel or aluminum plate. Corian might work >here too, as might MDF. > >The damping might come from a thin layer of sorbothane, isodamp, or the >auto-sound favorite, Dynamat, contrained within the sandwich (though I want >to be careful not to make the sandwich "squishy" or dimensionally unstable >as that would defeat the idea of rigidity and no relative motion between the >parts mounted to it). I don't want to get into "tuning" my table by >adjusting the torque of the bearing securing nut squeezing on the subchassis >sandwich! Certainly, a layer of damping under the subchassis is a good idea. > >So, before I change my mind in response to the next argument that comes >along, I envision a subchassis made of a sheet of steel or aluminum bonded >tightly to a piece of Corian with a thin layer of Dynamat between. This >sandwich supports the bearing and the armboard. It rests on a very thin >layer of sorbothane on top of a larger slab of Corian or marble or acrylic. >This slab is large enough to also have the heavy motor pod resting on top >(on it's own very thin layer of sorbothane), but not in contact with the >subchassis. This bottommost slab is resting flat on top of the sand in the >sandbox, in intimate contact over all of it's bottom surface. More energy >dissipation. > >Just my 2 cents worth. > >Steve Z >near Libby, MT > Subject: Re: [teres] isodamp; lossy approach is not the best? Date: Fri, 17 Mar 2000 12:18:48 -0700 From: Anya & Fred Humphrey, Anya & Fred Humphrey To: teres@aiko.com ----- Original Message ----- From: "Jon Lane" To: Sent: Tuesday, March 14, 2000 9:22 AM Subject: RE: [teres] isodamp; lossy approach is not the best? There is so much conjecture here in this lossy vs. closed-loop base discussion, backed up by very clever reasoning. I find it stimulating but also headache inducing, and like another member find myself agreeing with whoever has posted most recently. Even the empirical evidence has not always been as helpful as its authors doubtlessly intended, both because of a tendancy to leap to conclusions about the causes of the perceived effects, and, relatedly, because of a failure to eliminate variables. In Jon's fascinating post below, he makes a number of statements characterizing different decks. eg. the Maplenoll and SOTA have the "sonic blackness of a heavy, quiet design". Well, my Maplenoll Ariadne (85 #'s of lead and Corian not counting the platter) has this, and, yes, I'd expect the Sota to be similar here, but that hasn't been my experience. With Atmosphere OTL's and Snell A's and Talisman(?) cartridge, the noise level made the Chesky Lt. Kije unlistenable. The Linn and Oracle have more detail? Again, not in my experience. Mid-80's Linn's with their mid-bass hump were a joke, at least to my ears. In terms of detail, as opposed to timing,etc., the biggest improvement hasn't really been to the deck at all; the Ekos arm shows how much the Linn is really capable of. But I think it would be a dramatic improvement on most TT's. My old Oracle Alexandria was bright, I assume because of undamped arm resonances, but not particularly detailed. The Delphi's I've heard have been impossibly bright. I'm reluctant to blame it on the TT though; more likely bad setup by dealers who've damaged their hearing and are trying to compensate. So, we've got inconclusive empirical evidence and conflicting theoretical arguments. No wonder people are afraid they may end up just staring at their platters and motors. What to do? What do the Brits say? "Suck it and see." I'm a little nervous about what that actually means, but the idea is useful. I'll build my sandbox and air pillow support (NOT innertube - too unstable) as a permanent structure. Mine will be a bit atypical since the platter will have to hang out an inch or two over the edge of the sandbox so I can try rim drive. And I have to review the strobe disc geometry to see where I can actually drive the platter. But for the all-important base that's consumed so much thought these past few weeks, I'm just going to cobble together (that ought to offend Jon's precision engineering sensibilities) an I-beam out of MDF and see what it sounds like. Actually it will be more like an inverted U-beam, and the sides won't be parallel; it will be wider at the bearing than under the arm. The sides will be buried in the sand, and the top-plate will sit on the sand. Cheap, easy to make, quite rigid, lossy, and if it doesn't sound great I can try something else or refine the approach. > Two reasons. > > 1. The mechanical loop needs to be as lossless as possible > otherwise tiny internal bending ("resonance" being the > trendy audiophile word for this) interrupts the ability for > all energy to appear at all places. If the latter does not > occur, logically we can see how this energy would be > localized through inadequate transmission. > > 2. Directly pursuant to this (or perhaps as just a > different interpretation of the same thing), just as the 3" > acrylic is used to ensure a mechanical impedance match > between vinyl and platter for reasons of sinking resonance > (or high coupling if you prefer to see it that way), the use > of a thick alloy base is only one option that can do the > same sinking for the tonearm. > > Once again, any interruption of the loop obscures the > retrieval of fine detail. SOTA's and Maplenol's have the > sonic "blackness" of a quiet, heavy design, but neither has > the detail and focus of a Linn or Oracle, the latter two > going to pains to maximize the mechanical loop. The SOTA > decouples the parts with liberal use of lead and pressboard > including a thin armboard, the Maplenol is a completely > decoupled airbearing; while the Linn is rigid steel and > hardboard, and the Oracle mostly heavy alloy. The mother of > all coupled loop designs was the Goldmund, and was almost > universally regarded for the depth of it's information > retrieval. > > I explored the two philosophies over ten years ago and IMO, > the rigid loop blew the lossy subchassis completely away. > If you'll permit an unabashed opinion, I think too much > attention is paid to obsessing over stopping "resonance" > before it starts and not enough to coupling the essential > components as tightly as possible. One thing to bear in > mind is that there is literally no place for *internal* > resonance to come from outside of the stylus/record > interface which encounters the 3" platter immediately. The > platter-to-base-to-arm loop is dead quiet with a bearing of > this caliber, and the motor is completely isolated. Or > certainly should be. This leaves only out-of-system energy > needing attention and this is dealt with via sandbox or what > have you, all being accessories to the basic machine. The > use of a fundamentally lossy, bendy material (plexiglas, in > the case of the highly cosmetic designs) just begs for > decoupling/bending to the point that any energy found in > these parts is going to stay reactive longer, lower in > frequency, and local to its origin and will subtly color the > proceedings. OTOH, as the theory goes, energy found in a > heavy, rigid, "conductive" chassis naturally appears > "everyplace" in the structure with a minimum of resonant > bending, and can be damped critically after the fact as the > designer wishes. Further, the sheer rigid mass couples all > the way back into the arm and bearing themselves, > attenuating their contribution to the vibrational soup - > lossy chassis cannot do this, leaving either or both to > their own devices. As a speaker designer, I see this > analogous to never being able to critically damp a > undersized box, but being able to critically damp an > oversized box by reducing it's Q. While the analogy appears > inverted, the notion is that one can design with the > intention of critical damping after the fact. > > Apologies for the overt editorial, but I felt this was still > an area of mixed understanding. > > Jon Lane > > > > -----Original Message----- > > From: owner-teres@aiko.com > > [mailto:owner-teres@aiko.com]On Behalf Of > > Sellek, Grant (TSA) > > Sent: Tuesday, March 14, 2000 2:47 AM > > To: 'teres@aiko.com' > > Subject: RE: [teres] isodamp; lossy approach is > > not the best? > > > > > > What is the essential nature of the discontent > > with the "lossy" approach? > > > > I cannot imagine why "more rigid materials" > > should be cause for celebration, > > unless one was upgrading from a relatively > > lightweight lossy approach (dare > > I say a "floppy" approach) to a more massive > > rigid approach. I can see how > > this may be an upgrade. But I cannot see why a > > massive, lossy approach > > should be flawed. > > > > Any takers? > > > > > > Grant Sellek > > Adelaide, Australia > > grant.sellek@transport.sa.gov.au > Subject: Re: [teres] isodamp Date: Fri, 17 Mar 2000 12:51:51 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Last night I hook up the seismic generator to my sony pro cassette and listened with headphones at the TT . Now I know why they call it rumble, in my TT the sound changes, gets worse then better at the rotation rate. I did this because my the line amp in the Michigan logger is noisy and this generator picks up lots of interference. The signal on the scope changes as the TV screen changes, so I figured that by listening I can filter thru the noise. Need better headrooms with low cutoff or a freq. conversion so that subsonics are easy to detect. Stan At 07:41 PM 3/15/2000 -0500, MaughanAudio@aol.com wrote: >In a message dated 3/15/00 11:21:35 AM Mountain Standard Time, >sgoudge@cisco.com writes: > ><< I do have a ultra sensitive seismic generator I bought at supplus for $5 >many > years ago. >> >Great tool, Stan. Update us on the local seismic activities. By the way on my >lengthy note regarding rigid and lossy system loop interface, I forgot to say >bye! > >Until again, Gordon. > Subject: Re: [teres] Strobo disc Date: Fri, 17 Mar 2000 14:30:48 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Guys, We have another vendor playing the same game, just got the data from soundown. Prices and data are similar so might be a coin flip. Just got off the phone with Joe Quiet, he's the engineer at soundown and had quit a bit to say, so I gave him Teres link so he may be giving us some valuable info thru the list. Hopefully he can make since of some of our B.S..., err, ideas. Stan http://www.soundown.com/ http://www.earsc.com/new/ At 11:49 AM 3/17/2000 -0700, Thom Mackris wrote: >Manfred, > >Stanley Goudge had brought a series of damping materials to our attention - >all going by the company name of Isodamp. They have adhesive on either one >or both surfaces. Some are soft, and one (CN68) is a thick .5" thick plate >or tile (.5" = 12.5 mm). > >I will hopefully be putting out a couple of digests this weekend (for Chris >to put on the website). The category will be subchassis & motor pod. I >have all of the posts stored on my home computer, but not accessible from >(this) yahoo mailbox. > >Here are a couple of recent posts which I do have access to at the moment: > >-- Daus wrote: > >Hi everyone, >I found out that "super matereial" that I saw in my >vibrations class. It is manufatured from EAR specialty >composites and is labeled CN-62. Yes, this an an >ISODAMP material. I understand that some people are >ordering the sheet, but this is a .5" thick tile. It >is also quite strong like plexiglass. I love the >4.50lb/sqft spec!! Another material I found was c- >1002. This is 1" thick and I believe a solid vinyl and >like 6.50 lbs/sqft! I will look into this a little >more when I have some more time. The other company >that made the some similar stuff that I knew was >"Sounddown". Daus > >-- Stan Wrote: > >Yes if anyone wants any CN-62 I'll put it down. Its $15.42 ea. 1' x1' tile >and $18.06 ea. 1' x 1' tile both sides peel and stick. The order for the >Isodamp has not been placed yet, need checks first guys. >The C-1002 is more flexible and has a wider effective temp. range than >the CN-xx, but is not near as lossy at room temp. >The CN-xx is designed to damp rigid metal structures like submarines, but >also is effective on >Corian and Acrylic. > >Stan > >Cheers, >Thom > >----- Original Message ----- >From: Manfred Huber >Sent: Friday, March 17, 2000 2:59 AM >Subject: Re: [teres] Strobo disc > > >[ snip ] > >>Perhaps the best option would be to use >>double-sticky-sided CN12 plus the heavy photo paper. > >CN12? > >Regards >Manfred > >------------------ >Manfred Huber >MHuber@t-online.de >------------------ > > > > >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com >