Subject: Re: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 00:04:35 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Peter, Polished copper certainly does have a nice look, but be sure to clear coat it so that it stays that way. The clear coat will also give the surface a feeling of depth, which can be played up with multiple coats, possibly with a light sprinkle of something in between coats to add a 3-D layer-over-layer effect. Igor --- phclark wrote: > > ----- Original Message ----- > From: "Igor Kuznetsoff" > To: > Sent: Thursday, February 17, 2000 2:00 PM > Subject: RE: [teres] > Teres-Motor&Supply/Shield&Damping > > > > Ron, > > Mass loading the motor pod was discussed some > time > > ago, early in the project. > . Copper is, while also not exactly cheap (but we > only need a > > little), easily obtainable, and cheaper than > mu-metal. > > I have a source locally, Phoenix, for copper @ > $2.00/lb, approx. 12" x 24", > up to 1/8" thick that I've used for chassis tops and > bottoms. This might > have an application here. The same outfit also has > varying lengths of > copper pipe of varying diameters at the same price, > for the adventurous. > I'm considering this myself, mainly for cosmetic > purposes. > > Cheers, > > Peter C > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 01:06:41 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Scott, Oil & lead is an excellent way to absorb vibration. Back around '85 or so, I built some highly effective absorption units out of mason jars, soft open cell foam rubber (for a suspension medium), and an assortment of sizes of lead ("split shot") fishing weights. With some glue & heat I bonded the weights onto a pair of strips of the foam, rolled them up like a jelly roll & inserted these assemblies into the mason jars. I then filled them with oil, capped, and coated them with fiberglass resin (to make sure they could not ever leak). These then went into a pair of super-high tech silica sand filled satellites, which I still use. The satellites enjoy a two stage decoupling suspension, among a lengthy list of original tricks (at least at that time, some have been duplicated singly here and there since). I wanted these viscous absorbers to kill anything that the suspension couldn't stop. They worked fabulously well. Shaking one of these in the hand felt a lot like trying to shake a large egg. You know about trying to spin a raw egg vs. a hardboiled one? It's an old school days science experiment. The raw egg will resist the spin, coming to a halt very quickly. Try it if you aren't familiar with this already, it's an interesting demonstration of a viscous effect. This trick *can* be adapted to the motor housing, but I would be concerned about ever moving the result anywhere. If this arrangement were to be turned over accidentally, the motor would end up a mess, unless it is a hermetically sealed unit. So, it would have to be sealed off from the oil chamber for safety, adding another detail in order to gild the lily in two layers of precious metals, so to speak. When you gild with two layers, you only get to see the last one. The first one is wasted. Are you sure you want to do this? I admit that the idea is tempting to a fanatic like myself, but I plan to ground the motor housing mechanically to a pocket of sand mixture which will be acoustically isolated from the rest of the TT, which will be grounded likewise on its own decoupling isolated pocket of same. Seems like this ought to be enough if the motor pod is already heavy with lead ballast/damping, and sand. Of course, not everyone will be using the sandbox concept, and perhaps this will be worthwhile to try building, if a bit complicated to realize properly. What weight of oil would you recommend? Seems I vaguely remember using straight 30W or 40W or so, but it's been a long time since I built those devices. Igor --- Thom Mackris / Joan Panzella wrote: > I like this!! > > So one thing we want to be certain of is that our > motor pod is not > permeable. MDF would be a bad choice, unless we > coated it with polyurethane > (or C37 ). > > Cheers, > Thom > > > ----- Original Message ----- > From: Scott Fraser > To: > Sent: Thursday, February 17, 2000 4:16 PM > Subject: RE: [teres] > Teres-Motor&Supply/Shield&Damping > > > Mass helps, but something lossy in combination with > the mass makes the > system perform much better. > > On our most critical optical components we use an > old trick of filling a > chamber in the housing not with lead, but with lead > shot and then filling > the space around that with light mineral oil. The > dashpot action of oil on > the shot is great at eliminating the motions that > mass alone would leave > behind.... > > Tested this on a Scheu and it is quiet. > > Scott > > > > > > = = = = = = = = = = = = = = = = = > Scott Fraser (sefraser@caltech.edu) > Caltech, Beckman Institute (139-74) > Pasadena, CA 91125 > 626 395-2790 telephone > 626 449-5163 fax > > > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 03:37:34 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Igor, I certainly agree that it is a good idea to apply shielding to the motor unit. Fortunately I can tell from my own experience the RFI/EMI generated by the Maxon dc motor is very low. I'm using it in a housing made of wood (mass loaded with lead shot) and there is no problem with RFI/EMI even with my Grado reference wood MM cartridge which is a bit notorious in this regard. One important thing to consider when making a housing is mechanical noise. I find it very annoying when I can hear the motor from my listening position. The maxon motor runs quiet but you have to take care the housing is non-resonant and that the used material has good inner damping. You definitely do not want the housing to resonate with the mechanical vibrations generated by the motor. I choose wood mainly because I had the tooling needed to work with this material. If I had a lathe I would have built a cylindrical housing from copper. Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 07:34:47 -0700 From: Paul Croft, Paul Croft To: teres@aiko.com Hi Igor, Could you expand on the clear coat idea? What is the name of the clear coat you would recommend? Also, what is the "light sprinkle" you refer to? Thanks, Paul > -----Original Message----- > From: owner-teres@aiko.com [mailto:owner-teres@aiko.com]On Behalf Of > Igor Kuznetsoff > Sent: Friday, February 18, 2000 1:03 AM > To: teres@aiko.com > Subject: Re: [teres] Teres-Motor&Supply/Shield&Damping > > > Peter, > Polished copper certainly does have a nice look, > but be sure to clear coat it so that it stays that > way. The clear coat will also give the surface a > feeling of depth, which can be played up with multiple > coats, possibly with a light sprinkle of something in > between coats to add a 3-D layer-over-layer effect. > > Igor Snip... Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 09:08:40 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Hi, Paul: There are many choices for coating copper and other polished metals to keep their finish from tarnishing. Common Krylon clear protectant finish in an aerosol spray can will work well if you take care in applying it. You can get different levels of glossiness. For a clear coat, I prefer a matt or a semi-gloss finish, but that's strictly personal preference. I've also used Testors Clear Coat and Dull Coat, available at hobby shops either in spray cans or for air brushes. Dull Coat is obviously a very flat finish, and it looks good on the aluminum top plate of my 300B amp chassis. Makes the aluminum look kinda like old silver. The Testors products are probably not as durable as Krylon, but our applications shouldn't see much abuse. For a really exotic finish on copper, I would try a hand-rubbed shellac finish. It will give the copper a deep, warm, old-instrument lustre. Shellac takes a little practice to get it right, though. A shellac finish should be protected with a coating of fine furniture polish (not Pledge, anything aerosol, or anything you would probably find in a grocery or discount store). One nice thing about shellac is that it is probably the easiest finish to repair or restore; just the opposite of polyurethane. Shellac can be damaged by alcohol, though, so don't set your Scotch on it. :>) Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Paul Croft [SMTP:pcroft@iximd.com] > Sent: Friday, February 18, 2000 6:29 AM > To: teres@aiko.com > Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping > > Hi Igor, > Could you expand on the clear coat idea? What is the name of the clear > coat > you would recommend? Also, what is the "light sprinkle" you refer to? > Thanks, > Paul > > > -----Original Message----- > > From: owner-teres@aiko.com [mailto:owner-teres@aiko.com]On Behalf Of > > Igor Kuznetsoff > > Sent: Friday, February 18, 2000 1:03 AM > > To: teres@aiko.com > > Subject: Re: [teres] Teres-Motor&Supply/Shield&Damping > > > > > > Peter, > > Polished copper certainly does have a nice look, > > but be sure to clear coat it so that it stays that > > way. The clear coat will also give the surface a > > feeling of depth, which can be played up with multiple > > coats, possibly with a light sprinkle of something in > > between coats to add a 3-D layer-over-layer effect. > > > > Igor > Snip... Subject: Re: [teres] Teres-Finish Date: Fri, 18 Feb 2000 10:01:22 -0700 From: Jeremy Epstein, Jeremy Epstein To: teres@aiko.com "Schei, Kenneth" wrote: > > Hi, Paul: > > There are many choices for coating copper and other polished metals to keep > their finish from tarnishing. Note that unprotected copper tarnishes to a warm dull brown after a few months (indoors.) The blue/green patina never happens indoors in my experience. The copper has to be exposed to the outdoors for that to occur (but you CAN induce it chemically, I think with sulfur compounds.) A ScotchBrite pad and some Bon Ami copper cleaner will shine it back up after the brown tarnish occurs, with little effort. It looks really good shiny, and I also like the dull brown no-maintenance look pretty well too. Unless clear coated, it can get scratched but I have found this to be minimal and unobtrusive in my experience, however, there are different annealing hardnesses of copper, so I guess the really soft stuff would scratch more easily. If you are buying copper sheet for amp top plates, I would think the soft stuff might not support transformers, etc., whereas the hard stuff would be somewhat more difficult to bend and saw. If using the usual plain rectangular flat plate atop a wooden base, get the hard annealed copper. My bedframe is made of copper tubing, and it was never clear coated, is how I know the stuff about the finish. -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: [teres] Subchassis & Armboard Date: Fri, 18 Feb 2000 10:18:47 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'Teres_List' >From the Joe List ... Thom -----Original Message----- From: PEARL Cust Serv [mailto:custserv@pearl-hifi.com] Sent: Thursday, February 17, 2000 7:46 PM To: sound@lists.io.com Subject: [JN] AEROSPACE Composite Products Catalog Home Page Hi All: Here's a link to a very interesting company supplying, as their name indicates, high tech composite products. They carry a very broad range of products and have been around for years http://www.deltronix.com/public/acp/ACP-CAT.HTM Bill - PEARL, Inc. Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 11:30:03 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Manfred, This is good news, thanks for the info. I certainly agree about the noise. I've been known to build remote fans & piping the air in or out with flex duct for that reason. Also setting refrigerators on vibration isolating devices, hanging dehumidifiers with bungee cord suspensions, etc. Scott Fraser had a good suggestion, if a bit awkward to implement safely, yesterday about oil & lead mass loading/vibration damping for motor pods. Igor --- Manfred Huber wrote: > Igor, > > I certainly agree that it is a good idea to apply > shielding > to the motor unit. Fortunately I can tell from my > own experience > the RFI/EMI generated by the Maxon dc motor is very > low. I'm > using it in a housing made of wood (mass loaded with > lead shot) > and there is no problem with RFI/EMI even with my > Grado > reference wood MM cartridge which is a bit notorious > in this regard. > > One important thing to consider when making a > housing is mechanical noise. > I find it very annoying when I can hear the motor > from my listening position. > The maxon motor runs quiet but you have to take care > the housing is non-resonant > and that the used material has good inner damping. > You definitely do not want > the housing to resonate with the mechanical > vibrations generated by the motor. > > I choose wood mainly because I had the tooling > needed to work with this material. > If I had a lathe I would have built a cylindrical > housing from copper. > > Regards > Manfred > > > ------------------ > Manfred Huber > MHuber@t-online.de > ------------------ > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: [teres] Subchassis & Armboard Date: Fri, 18 Feb 2000 12:09:05 -0700 From: steve brooks, steve brooks To: teres@aiko.com No one has mentioned and I know it would be expensive, but what about carbon fiber...maybe only for the armboard? Would there be any advantage in using it for the subchasis? By the way it's expensive. But if we bought as a group it would still be expensive. Steve Brooks BTW, The mail list won't let me send my JPEG's so I'll ask Chris if he wants to put them on his website. Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 13:08:59 -0700 From: Mikhail Karlin, Mikhail Karlin To: teres@aiko.com Reading all nice ideas about mass loading of the motor pod and its placement on the subchassis I came up with a question: the mass loading'll lead to the shift of the center of gravity of loaded subchasses away from the center of rotation of the platter.This means that the weight which action passes through the center of gravity'll create some vertical torque in reference to the center of rotation. Is it important that both centers to be at the same point or the mechanical and damping qualities of the system'd makethe effect negligable. Any way we could bring the center of gravity back by changing position of cones under subchasses or(and) by mass loading of the lighter part of subchasses. Any comments? Michael On Thu, 17 Feb 2000, Igor Kuznetsoff wrote: > Ron, > Mass loading the motor pod was discussed some time > ago, early in the project. It is a fine idea, and > should certainly be done. Lead by itself would > probably be too dimensionally unstable to form a > housing out of, and, of course, the motor could not be > mounted directly to it. But, using it to form a > housing, as per your suggestion is a still a good > idea. It would be more practical to find an > attractive metal housing of the right size, with a > convenient wall thickness, and use it *as* the > non-detachable mold & outer cosmetic. What I mean is > pour the lead right into it, and leave it attached. A > second (smaller, of course) container or sleeve of > metal, say easily formable copper, which would also > serve as a (partial) shield (or use mu-metal,as > suggested below) could be used to make the inner > form/wall, and the lead poured between them, leaving > the inside hollow. Doing it this way is simpler *and* > more effective, *both*. This would result in a top of > stiffer metal, sides shielded/ reinforced/damped/mass > loaded, and bottom, depending on how you orient & > arrange the parts. Additional shielding could easily > be added to the (thin, possibly only decorative in > terms of shielding) top by laminating a shielding > layer of your choice. Mu-metal is indeed the material > of choice, but pricey, I noticed, from looking at > several catalogs that I have, some time ago. Copper > is, while also not exactly cheap (but we only need a > little), easily obtainable, and cheaper than mu-metal. > It can be obtained from roofing supply houses in a > fairly respectably thick gauge. They use it for > flashing & other roofing work. Also for trim & fancy > range hoods occasionally in "designer" kitchens. > Copper can also be obtained from hobby supply shops in > small sheets, and from Dick Blick's Art Supply. > Chances are, if you call a roofer or three, you can > obtain cutoffs for next to nothing, if that. Please > keep in mind that while copper is very good with > RFI, it is not as good with EMI, and that is what the > motor is likely to put out, even our DC motor, as Ken > pointed out earlier. Steel can actually be a better > shield for EMI than copper, making it a likely choice > for the box, unless you can find a monel metal box of > suitable size. Interestingly, while monel is > expensive now, back during the '50's or so a lot of > restaurant counters & containers were made of monel > because it has rust & corrosion resistance properties > akin to that of stainless steel. If you have some > idea of how to find some of that... > The most practical combo of choice would be to > use copper sheet for the inside wall form, and a sheet > of mu-metal laminated to the underside of the top. > This would keep the top thin but effective, and the > thick sidewalls of copper/lead/whatever metal the box > is made of should be plenty effective as well. > Whatever space is left under the motor can be filled > with, you guessed it, sand/whatever, if you like, but > I would suggest stabilizing its location somehow by > "skinning" its surface with whatever is handy that's > rubbery & flexible, so that it cannot get into, or > even onto, the motor. Or just go with all lead, so > long as you are working with it anyway. The addition > of sand would probably be superior to depending on > just the lead, as sand has good acoustic damping > properties that are different from lead, but this > would represent some additional fuss. If you do use a > sand mix, I suggest mixing in recycled tire rubber > chips before the addition of lead shot, which is also > a good addition, but secondary to the rubber chips. > Sorry, don't have time to rehash the virtues of rubber > chips, we beat that subject to death already earlier > in the project, please look up the old posts. It > might be a good idea to drill a few air holes for > cooling, but I do not know if these motors require > that under the loads we will subject them to. Perhaps > our motor experts will supply that datum. > Finally, please keep in mind that this is *not* > (by *any* crippling of the imagination) an AR. The AR > used an AC motor, and that was placed under the > platter. We > are (most of us) using a DC motor, and it will be > placed away from the playing area the cartridge will > be traversing. Even if the motor is placed on the > non-traditional right side, something that made Ken > nervous the other day. Even if on the right side, > when the cartridge is in play, the arm with cart & > wiring are *moved away* from the general location of > the motor, which, obviously, should not be placed any > closer to the sensitive parts than can be helped. a > matter of choice & careful implementation. A little > shielding to be sure, and we should good. > > Igor > > --- "Mackris, Thom G." > wrote: > > Ron, > > > > Lead and other mass loading/damping seems like a > > fine idea to me. Would > > solid lead be better than say a mix of lead shot & > > sand? Comments from our > > damping experts?? > > > > Something like the box in Chris' preliminary drawing > > would certainly afford > > a lot of volume to (a) load up with mass and (b) > > house the controller. I'll > > bet we could get that pod to weigh 15 lbs. (that's 7 > > kilos to the rest of > > you folks) without tring too hard. > > > > BTW, a co-worker I knew in California was a skeet > > shooter (clay pidgeons - > > shotgun). He told me that skeet ranges sell > > recycled lead shot at about 50% > > off the normal retail price. I have not verified > > this. > > > > Thom > > > > -----Original Message----- > > From: Ron Welborne [mailto:wlabs@ix.netcom.com] > > Sent: Thursday, February 17, 2000 10:12 AM > > To: teres@aiko.com > > Subject: Re: [teres] Teres-Motor&Supply > > > > > > > > Possibly one of my last suggestions ended up in the > > 'domo bit bucket. Here > > goes again: > > > > The motor should be mounted in/on a very heavy mass > > to help isolate from > > vibrations. I previously suggested a housing or > > base manufactured from > > lead. It seems that a simple mold could be easily > > created and then poured > > by ourselves. Lead is soft thereby making it easy > > to work with. > > > > A lead cup, or square box, with the motor mounted to > > the lid is one possible > > option. > > > > A cylindrical lead base fitted with a PVC cover > > might be another option. > > > > Any thoughts out there on using lead? > > > > > > Ron > > > > Welborne Labs > > wlabs@ix.netcom.com > > ph: 303.470.6585 > > fax: 303.791.5783 > > website --------------- www.welbornelabs.com > > ----------------- > > > > ----- Original Message ----- > > From: Mackris, Thom G. > > To: > > Sent: Thursday, February 17, 2000 8:52 AM > > Subject: RE: [teres] Teres-Motor&Supply > > > > > > > Hi Bill, > > > > > > Chris is out of town on business today (Thursday) > > through tomorrow > > (Friday), > > > so let me take a first crack responding to your > > request to consider > > > including some form of steel shielding or housing > > for the motor. > > > > > > If you're talking about some kind of "can" to slip > > over the motor, then > > > perhaps mu-metal is the solution you're looking > > for. Additional good good > > > news comes from the fact that we're using a DC > > motor so other than some of > > > the garbage resulting from the brushes, the motor > > will be fairly quiet > > from > > > an electrical noise standpoint. > > > > > > At the end of this reply, I'm attaching a thread I > > compiled from last year > > > from the Joe list on sourcing mu-metal. Note the > > comments about thin > > guage > > > and easy conformability. Since we're likely to > > diverge in our concepts of > > > motor housing / subchassis, this is important - > > one size does not > > > necessarily fit all solutions. > > > > > > My current two thoughts for housing/mounting the > > motor are (a) Something > > > resembling the preliminary drawing that Chris put > > up on his website and > > (b) > > > a cylinder made of PVC tubing - finished with > > Hammerite or some other > > > tough/glossy finish. Chris' option looks to be a > > bit more flexible as it > > > affords the opportunity for more mass loading, as > > well as a housing for > > the > > > controller board. > > > > > > Cheers, > > > Thom > > > > > > -------------------------------------- > > > Compiled thread follows .... > > > -------------------------------------- > > > > > > > > > Hi all - > > > > > > From Joe_List (#313 & #369), John Leverault noted > > that our > > > favorite bad-boy, Corey Greenberg discussed some > > hum busting techniques > > for > > > Grado Cartridges and Rega 'tables in this July's > > Audio Magazine (p22-25) > > of > > > all places. > > > > > > He uses a Mu-Metal kit from: > > > > > > Magnetic Shield Corporation (630) 766-7800 ... > > product # LK-110 > > > > > > Hum and (unshielded) Grados has traditionally been > > a problem with the AR > > > turntables which I had highly recommended to Chris > > (BTW, no hum problems > > in > > > my friends' with a Shure cartridge). This would > > be great if you could > > mate > > > these two products without a hum problem. > > > > > > and ... from Joe_List vol 369 (7/31/98) .. > > > > > > > > > Date: Fri, 31 Jul 1998 16:01:03 +1000 > > > From: "Ian McPhail" > > > Subject: mu metal hum job > > > > > > Anyone seen the interesting article in July 98 > > issue of Audio by Corey > > > Greenberg hum busting a Grado (unshielded) on a > > Rega Planar 3 (unshielded > > > motor). He mentions a try out kit of mu metal > > sample pieces avalable from > > > Magnetic Shield Corporation for $80. > > > http:://magnetic-shield.com/labkit.html > > > regards Ian > > > > > > Ian McPhail i.mcphail@rmit.edu.au > > > RMIT Chem and Met Eng Dept 110 > > > GPO Box 2476V > > > Melbourne 3001 > > > Australia > > > tel +61 3 9925 2408 > > > fax +61 3 9925 3746 > > > > > > ------------------------------ > > > > > > Date: Fri, 31 Jul 1998 02:16:08 EDT > > > From: Acrosound@aol.com > > > Subject: Re: mu metal hum job > > > > > > In a message dated 7/31/98 1:05:57 AM, Ian wrote: > > > > > > >Anyone seen the interesting article in July 98 > > issue of Audio by Corey > > > >Greenberg hum busting a Grado (unshielded) on a > > Rega Planar 3 (unshielded > > > >motor). He mentions a try out kit of mu metal > > sample pieces avalable from > > > >Magnetic Shield Corporation for $80. > > > >http:://magnetic-shield.com/labkit.html > > > > > > > > > If anyone needs little pieces of mu-metal for > > experimentation drop me an > > > email. I have some .006" thick material. If ya > > just need just a > > > little....it > > > === message truncated === > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com > Subject: Re: [teres] Subchassis & Armboard Date: Fri, 18 Feb 2000 14:50:13 -0700 From: WMollard, WMollard To: teres@aiko.com Hey Teresites, here is an interesting base... or "iso base". Does anyone have any expereince with this item? http://www.silentrunningaudio.com/prod02.htm best bill -----Original Message----- From: Mackris, Thom G. To: 'Teres_List' Date: Friday, February 18, 2000 8:35 AM Subject: [teres] Subchassis & Armboard >>From the Joe List ... >Thom > >-----Original Message----- >From: PEARL Cust Serv [mailto:custserv@pearl-hifi.com] >Sent: Thursday, February 17, 2000 7:46 PM >To: sound@lists.io.com >Subject: [JN] AEROSPACE Composite Products Catalog Home Page > > > Hi All: > Here's a link to a very interesting company supplying, as their name >indicates, high tech composite products. They carry a very broad range of >products and have been around for years > > > http://www.deltronix.com/public/acp/ACP-CAT.HTM > > > Bill - PEARL, Inc. > Subject: Re: [teres] Subchassis & Armboard Date: Fri, 18 Feb 2000 15:14:44 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com --- steve brooks wrote: > No one has mentioned and I know it would be > expensive, but what about carbon > fiber...maybe only for the armboard? Would there be > any advantage in using > it for the subchasis? By the way it's expensive. > But if we bought as a > group it would still be expensive. > Steve Brooks > Oh, heck, there's nothing that can't be solved by the frivolous waste of money copiously thrown at a problem. Just buy a large Diamond Racing Platform, drill & trim the thing down, diamond stud the perimeter, and voila ! A subchassis you can *really* brag about! And plenty of carbon! Weeeeel... It *is* an option! Just funnin' ya, but yes, that would be expensive. And, I hear, hard to work with. Igor :-) __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Fri, 18 Feb 2000 15:31:32 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Paul, Ken covers the subject nicely below. There are a lot of useful clear coating possibilities. For the "depth" effect I mentioned, you should use a glossy, or, at least, fairly glossy finish. This is a common technique used by the fancy show car painters. They spray multiple coats of clear, interspersed with *very light* touches of fine metalflake in an untinted clear base. By building up layers with solid particles at different depths, they develop a 3-D depth effect, which becomes apparent when you move around while viewing the painted object. This happens because you are seeing the particles occlude each other, with space in between. This effect can be achieved with light oversprays of color as well. Be warned, this takes a good deal of practice, and a *lot* of clear coats. I just meantioned it speculatively. Igor --- "Schei, Kenneth" wrote: > Hi, Paul: > > There are many choices for coating copper and other > polished metals to keep > their finish from tarnishing. Common Krylon clear > protectant finish in an > aerosol spray can will work well if you take care in > applying it. You can > get different levels of glossiness. For a clear > coat, I prefer a matt or > a semi-gloss finish, but that's strictly personal > preference. I've also > used Testors Clear Coat and Dull Coat, available at > hobby shops either in > spray cans or for air brushes. Dull Coat is > obviously a very flat finish, > and it looks good on the aluminum top plate of my > 300B amp chassis. Makes > the aluminum look kinda like old silver. The > Testors products are probably > not as durable as Krylon, but our applications > shouldn't see much abuse. > For a really exotic finish on copper, I would try a > hand-rubbed shellac > finish. It will give the copper a deep, warm, > old-instrument lustre. > Shellac takes a little practice to get it right, > though. A shellac finish > should be protected with a coating of fine furniture > polish (not Pledge, > anything aerosol, or anything you would probably > find in a grocery or > discount store). One nice thing about shellac is > that it is probably the > easiest finish to repair or restore; just the > opposite of polyurethane. > Shellac can be damaged by alcohol, though, so don't > set your Scotch on it. > :>) > > Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > > > -----Original Message----- > > From: Paul Croft [SMTP:pcroft@iximd.com] > > Sent: Friday, February 18, 2000 6:29 AM > > To: teres@aiko.com > > Subject: RE: [teres] > Teres-Motor&Supply/Shield&Damping > > > > Hi Igor, > > Could you expand on the clear coat idea? What is > the name of the clear > > coat > > you would recommend? Also, what is the "light > sprinkle" you refer to? > > Thanks, > > Paul > > > > > -----Original Message----- > > > From: owner-teres@aiko.com > [mailto:owner-teres@aiko.com]On Behalf Of > > > Igor Kuznetsoff > > > Sent: Friday, February 18, 2000 1:03 AM > > > To: teres@aiko.com > > > Subject: Re: [teres] > Teres-Motor&Supply/Shield&Damping > > > > > > > > > Peter, > > > Polished copper certainly does have a nice > look, > > > but be sure to clear coat it so that it stays > that > > > way. The clear coat will also give the surface > a > > > feeling of depth, which can be played up with > multiple > > > coats, possibly with a light sprinkle of > something in > > > between coats to add a 3-D layer-over-layer > effect. > > > > > > Igor > > Snip... > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Subchassis & Armboard Date: Fri, 18 Feb 2000 15:42:20 -0700 From: steve brooks, steve brooks To: teres@aiko.com I was thinking of having someone make it for us...I wouldn't know the first thing about machining Carbon Fiber..but if we went to someone who makes racing parts..I know of one here in Atlanta, and said we wanted 20 of these armboards or chasis...remember we don't have to worry about profit and dealer markup...so what seems expensive when you buy it on a Wilson Benesch may not be to us...or maybe it still would, I don't know but if there is interest in it, I would be happy to investigate. Steve > > Oh, heck, there's nothing that can't be solved by the > frivolous waste of money copiously thrown at a > problem. Just buy a large Diamond Racing Platform, > drill & trim the thing down, diamond stud the > perimeter, and voila ! A subchassis you can *really* > brag about! And plenty of carbon! Weeeeel... It *is* > an option! > > Just funnin' ya, but yes, that would be expensive. > And, I hear, hard to work with. Subject: Re: [teres] Subchassis & Armboard Date: Sat, 19 Feb 2000 14:57:43 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/18/00 23:53, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > Steve, > > Did you check out that aerospace link that I forwarded earlier from Bill's > Joe List post? > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > Carbon fiber plates and other stuff. I'd be curious in Ken's take on this, > what with his structural engineering background ... the meaning of the > numbers. > > Thom I haven't had time to do more than go there and bookmark the site (working night shift now 8^( It sounds interesting, but I am a bit of a skeptic regarding the "magical" properties of carbon fiber. Perhaps because I don't understand it enough. Though it is probably more dead and dimensionally stable than many other materials, I am wondering if it is enough so that the large price differential merits its higher price? And the characteristics of construction - direction of fibers, weave of the reinforcing cloth, layers, etc, all probably have a bearing on final suitability. It might still have to be mass-loaded and/or dampened to be optimum for our purposes. Not saying it's a bad idea, just saying I don't know enough, and there seem to be a lot of variables to consider. Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sat, 19 Feb 2000 20:37:01 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com Steve, Indeed, I don't think of carbon as being a silver bullet either. I hope I didn't convey that. All I had time to do was to add this site to my expanding bookmarks too. One day I'll get to go through this stuff :-(( I look at carbon as just another interesting material that might work in one context but not in another. Speaking of context, I had a long conversation with Chris today about tonearm mounting. We're trying to envision a mounting platform for the tonearm which does not compromise rigidity, energy sinking, etc. and yet is aesthetic. I can see why Verdier has that "tab" poking out on the right side of the 'table, but I'm striving for something a bit more elegant looking. Two obvious constraints to any design are access to (a) secure tonearm mounting as well as for (b) arm cable routing. My Audiocraft arm has a big threaded tube and a which passes through the armboard. A large nut secures the arm to the armboard. One needs either a big socket to secure the nut or enough access to use a big open end wrench. I believe that your Rega has similar mounting issues. Thom ----- Original Message ----- From: Steve Zettel To: Sent: Saturday, February 19, 2000 1:56 PM Subject: Re: [teres] Subchassis & Armboard on 2/18/00 23:53, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > Steve, > > Did you check out that aerospace link that I forwarded earlier from Bill's > Joe List post? > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > Carbon fiber plates and other stuff. I'd be curious in Ken's take on this, > what with his structural engineering background ... the meaning of the > numbers. > > Thom I haven't had time to do more than go there and bookmark the site (working night shift now 8^( It sounds interesting, but I am a bit of a skeptic regarding the "magical" properties of carbon fiber. Perhaps because I don't understand it enough. Though it is probably more dead and dimensionally stable than many other materials, I am wondering if it is enough so that the large price differential merits its higher price? And the characteristics of construction - direction of fibers, weave of the reinforcing cloth, layers, etc, all probably have a bearing on final suitability. It might still have to be mass-loaded and/or dampened to be optimum for our purposes. Not saying it's a bad idea, just saying I don't know enough, and there seem to be a lot of variables to consider. Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sat, 19 Feb 2000 21:39:52 -0700 From: phclark, phclark To: teres@aiko.com Thom et al., Here I was fat, dumb and happy, figuring I had a tenuous grip on my "new" TT project, and Thom (ever so casually) drops the bomb: >I believe that your Rega has similar mounting issues. (see below) Oh lordy. Based on previous posts addressing the subject specifically of a first pass (hot or not) at a tonearm for the Teres, I had decided to do the Origin modified Rega 250 (brass in the base being preferred to steel.) Am I being an alarmist about "mounting issues?" I was pretty much OK with the big honkin' retaining nut on the bottom of the Rega. Is there something I'm missing, something Mom Should Have Told Me, but Didn't? Anxious in Scottsdale, Peter C ----- Original Message ----- From: "Thom Mackris / Joan Panzella" To: Sent: Saturday, February 19, 2000 7:41 PM Subject: Re: [teres] Subchassis & Armboard > Steve, > > Indeed, I don't think of carbon as being a silver bullet either. I hope I > didn't convey that. All I had time to do was to add this site to my > expanding bookmarks too. One day I'll get to go through this stuff (( I > look at carbon as just another interesting material that might work in one > context but not in another. > > Speaking of context, I had a long conversation with Chris today about > tonearm mounting. > > We're trying to envision a mounting platform for the tonearm which does not > compromise rigidity, energy sinking, etc. and yet is aesthetic. I can see > why Verdier has that "tab" poking out on the right side of the 'table, but > I'm striving for something a bit more elegant looking. Two obvious > constraints to any design are access to (a) secure tonearm mounting as well > as for (b) arm cable routing. My Audiocraft arm has a big threaded tube and > a which passes through the armboard. A large nut secures the arm to the > armboard. One needs either a big socket to secure the nut or enough access > to use a big open end wrench. I believe that your Rega has similar mounting > issues. > > Thom > > > ----- Original Message ----- > From: Steve Zettel > To: > Sent: Saturday, February 19, 2000 1:56 PM > Subject: Re: [teres] Subchassis & Armboard > > > on 2/18/00 23:53, Thom Mackris / Joan Panzella at tmackris@earthlink.net > wrote: > > > Steve, > > > > Did you check out that aerospace link that I forwarded earlier from Bill's > > Joe List post? > > > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > > > Carbon fiber plates and other stuff. I'd be curious in Ken's take on > this, > > what with his structural engineering background ... the meaning of the > > numbers. > > > > Thom > > I haven't had time to do more than go there and bookmark the site (working > night shift now 8^( > > It sounds interesting, but I am a bit of a skeptic regarding the "magical" > properties of carbon fiber. Perhaps because I don't understand it enough. > Though it is probably more dead and dimensionally stable than many other > materials, I am wondering if it is enough so that the large price > differential merits its higher price? And the characteristics of > construction - direction of fibers, weave of the reinforcing cloth, layers, > etc, all probably have a bearing on final suitability. > > It might still have to be mass-loaded and/or dampened to be optimum for our > purposes. > > Not saying it's a bad idea, just saying I don't know enough, and there seem > to be a lot of variables to consider. > > Steve Z > > > > Subject: Re: [teres] Subchassis & Armboard Date: Sat, 19 Feb 2000 21:49:02 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Steve, Take a look at the tapered carbon fiber tubes they offer. .550" to .250" over 36" for ~$30 depending on wall thickness. A 10-12" piece from the small end would run about .250"-.350", for example. Perfect for arm tubes. Or any usage requiring strong, resonance resisting struts or standoffs. Also, they can be filled with anti-resonance materials for additional damping over and above the natural resonance distributing tapered shape & low res characteristics of carbon composites. Igor --- Steve Zettel wrote: > on 2/18/00 23:53, Thom Mackris / Joan Panzella at > tmackris@earthlink.net > wrote: > > > Steve, > > > > Did you check out that aerospace link that I > forwarded earlier from Bill's > > Joe List post? > > > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > > > Carbon fiber plates and other stuff. I'd be > curious in Ken's take on this, > > what with his structural engineering background > ... the meaning of the > > numbers. > > > > Thom > > I haven't had time to do more than go there and > bookmark the site (working > night shift now 8^( > > It sounds interesting, but I am a bit of a skeptic > regarding the "magical" > properties of carbon fiber. Perhaps because I don't > understand it enough. > Though it is probably more dead and dimensionally > stable than many other > materials, I am wondering if it is enough so that > the large price > differential merits its higher price? And the > characteristics of > construction - direction of fibers, weave of the > reinforcing cloth, layers, > etc, all probably have a bearing on final > suitability. > > It might still have to be mass-loaded and/or > dampened to be optimum for our > purposes. > > Not saying it's a bad idea, just saying I don't know > enough, and there seem > to be a lot of variables to consider. > > Steve Z > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 01:58:08 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com Peter, There's no problem with the mounting nut on the Rega or my Audiocraft. Other mouting techniques (Linn's multiple allen screws) present a variation on the same problem. You are not alone on this design issue. BTW, it seems as if we need to try to figure out a group buy on Origin Live Rega 250 mods. I'll bet there are at least a dozen candidates on this list for one. We'll just have to play around with a design for mounting arms that takes into account the fact that you need to turn a wrench in order to mount the arm. It seems as if functionality and aesthetics are at odds with each other on this issue, but I'm not giving up yet :-)) This problem (of mounting the arm) will of course be simpler for those of us who adopt a removable armboard because the arm can be cinched down prior to installing the armboard. If however, you follow Linn's doctrine of performing final cartridge tightening with the arm off the 'table, then you might have some problems in getting the exact same overhang after re-mounting the arm / board :-(( IOW, it behooves us to design accessibility into the system and not depend on a removable armboard for access to mounting the arm. Maybe I've been reading too much of George Merrill, but since I don't expect to change my arm in the near future, I'm hoping to make my subchassis with an integral armboard. Warning !! My thoughts are subject to change every 10 minutes at this point in the design. One case that can be made against a fixed armboard is that perhaps we can effect some final tuning by trying different armboard materials - acrylic, acrylic/aluminum, carbon fiber ?? What we'll never know is whether the best one we find will approximate a fixed armboard or exceed it. For those of you who are not familiar with Linn's doctrine, they condend that final cartridge bolt tightening should be performed with the arm off the 'table in order to keep from putting unnecessary force on the bearings. Linn is the only manufacturer I know of who issues this caution, so I don't know how valid it is, especially for someone who doesn't exercize a gorilla grip on the arm when tightening down a cartridge. Another problem for Rega owners who do not adopt some form of VTA adjustable base is the necessity of removing the arm in order to add or remove VTA adjusting shims (ouch !). I'd definitely go for the adjustable base (Origin Live's or a personal design) on any 'table I mounted a Rega. Not so anxious, but extremely interested in the eventual outcome ... Thom Original Message ----- From: phclark To: Sent: Saturday, February 19, 2000 8:25 PM Subject: Re: [teres] Subchassis & Armboard Thom et al., Here I was fat, dumb and happy, figuring I had a tenuous grip on my "new" TT project, and Thom (ever so casually) drops the bomb: >I believe that your Rega has similar mounting issues. (see below) Oh lordy. Based on previous posts addressing the subject specifically of a first pass (hot or not) at a tonearm for the Teres, I had decided to do the Origin modified Rega 250 (brass in the base being preferred to steel.) Am I being an alarmist about "mounting issues?" I was pretty much OK with the big honkin' retaining nut on the bottom of the Rega. Is there something I'm missing, something Mom Should Have Told Me, but Didn't? Anxious in Scottsdale, Peter C ----- Original Message ----- From: "Thom Mackris / Joan Panzella" To: Sent: Saturday, February 19, 2000 7:41 PM Subject: Re: [teres] Subchassis & Armboard > Steve, > > Indeed, I don't think of carbon as being a silver bullet either. I hope I > didn't convey that. All I had time to do was to add this site to my > expanding bookmarks too. One day I'll get to go through this stuff (( I > look at carbon as just another interesting material that might work in one > context but not in another. > > Speaking of context, I had a long conversation with Chris today about > tonearm mounting. > > We're trying to envision a mounting platform for the tonearm which does not > compromise rigidity, energy sinking, etc. and yet is aesthetic. I can see > why Verdier has that "tab" poking out on the right side of the 'table, but > I'm striving for something a bit more elegant looking. Two obvious > constraints to any design are access to (a) secure tonearm mounting as well > as for (b) arm cable routing. My Audiocraft arm has a big threaded tube and > a which passes through the armboard. A large nut secures the arm to the > armboard. One needs either a big socket to secure the nut or enough access > to use a big open end wrench. I believe that your Rega has similar mounting > issues. > > Thom > > > ----- Original Message ----- > From: Steve Zettel > To: > Sent: Saturday, February 19, 2000 1:56 PM > Subject: Re: [teres] Subchassis & Armboard > > > on 2/18/00 23:53, Thom Mackris / Joan Panzella at tmackris@earthlink.net > wrote: > > > Steve, > > > > Did you check out that aerospace link that I forwarded earlier from Bill's > > Joe List post? > > > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > > > Carbon fiber plates and other stuff. I'd be curious in Ken's take on > this, > > what with his structural engineering background ... the meaning of the > > numbers. > > > > Thom > > I haven't had time to do more than go there and bookmark the site (working > night shift now 8^( > > It sounds interesting, but I am a bit of a skeptic regarding the "magical" > properties of carbon fiber. Perhaps because I don't understand it enough. > Though it is probably more dead and dimensionally stable than many other > materials, I am wondering if it is enough so that the large price > differential merits its higher price? And the characteristics of > construction - direction of fibers, weave of the reinforcing cloth, layers, > etc, all probably have a bearing on final suitability. > > It might still have to be mass-loaded and/or dampened to be optimum for our > purposes. > > Not saying it's a bad idea, just saying I don't know enough, and there seem > to be a lot of variables to consider. > > Steve Z > > > > Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 02:07:12 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/19/00 19:41, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > Steve, > > Indeed, I don't think of carbon as being a silver bullet either. I hope I > didn't convey that. No, not at all. > > Speaking of context, I had a long conversation with Chris today about > tonearm mounting. > > We're trying to envision a mounting platform for the tonearm which does not > compromise rigidity, energy sinking, etc. and yet is aesthetic. I can see > why Verdier has that "tab" poking out on the right side of the 'table, but > I'm striving for something a bit more elegant looking. Two obvious > constraints to any design are access to (a) secure tonearm mounting as well > as for (b) arm cable routing. My Audiocraft arm has a big threaded tube and > a which passes through the armboard. A large nut secures the arm to the > armboard. One needs either a big socket to secure the nut or enough access > to use a big open end wrench. I believe that your Rega has similar mounting > issues. I am having the same conceptual problems. As you note, my Rega's require access to the mounting nut. I was considering several 1" thick rings of Corian, topped with a matching or contrasting slab drilled to accept the arm tube. Or maybe the top disc will be a frosted acrylic to match the cosmetics of the platter. Or maybe the arm towers will be completely acrylic. Anyway the bottom one or two would be more like hollow rings with a portion missing, oriented toward the back of the turntable, to allow access. I have been thinking about saving the missing segments and replacing them when access is not needed. A smaller hole drilled through the subchassis slab would allow the tonearm cables to exit underneath the subchassis (and sand). Glue would be one method for laminating the sections of acrylic or Corian together; another alternative (the high-tech look) would be to use stainless steel socket cap head bolts all the way through the subchassis and arm mounting towers. Let me know what you all think -- this group consistantly has better ideas collectively than spring up unassisted from my own imagination. Thanks, Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 02:19:50 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/19/00 20:25, phclark at phclark@uswest.net wrote: > Thom et al., > > Here I was fat, dumb and happy, figuring I had a tenuous grip on my "new" TT > project, and Thom (ever so casually) drops the bomb: >I believe that your > Rega has similar mounting issues. (see below) > > Oh lordy. Based on previous posts addressing the subject specifically of a > first pass (hot or not) at a tonearm for the Teres, I had decided to do the > Origin modified Rega 250 (brass in the base being preferred to steel.) > > Am I being an alarmist about "mounting issues?" I was pretty much OK with > the big honkin' retaining nut on the bottom of the Rega. Is there something > I'm missing, something Mom Should Have Told Me, but Didn't? > > Anxious in Scottsdale, > > Peter C Nothing to be anxious about, Peter. I am going to mount not one, but two Rega RB-300 arms on my Teres. I think the concern Thom expressed was valid for *whatever* tonearms we use -- how best to have a rigid, non-resonant arm-mounting platform and still have access to arm wiring and mounting bolts. That the Regas use one large nut instead of several smaller bolts arount the periphery is really no big deal. Almost all of the subchassis designs I have heard about so far posit rather thick and massive dimensions, and might pose problems with drill small or large holes. One solution for the access to the Rega nut would completely eliminate the need for getting a wrench or socket in under the arm-mounting board: have a welder tack two tabs on the face of the nut, 180 degress apart to turn it into a wing-nut. The nut doesn't have to be torqued to a tremendous tightness, a stout "finger-tight" will do it. A castellated nut of the same size would allow tightening by inserting a screwdriver through an access slot to engage the slots in the nut for turning. I am sure there are other, inventive ways to skin this cat. I don't see anything out there to better the Regas, until you start talking much more $$$ for a tonearm. My humble opinion, Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 02:21:48 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/19/00 20:47, Igor Kuznetsoff at gorkuz@yahoo.com wrote: > Steve, > Take a look at the tapered carbon fiber tubes > they offer. .550" to .250" over 36" for ~$30 > depending on wall thickness. A 10-12" piece from the > small end would run about .250"-.350", for example. > Perfect for arm tubes. Or any usage requiring strong, > resonance resisting struts or standoffs. Also, they > can be filled with anti-resonance materials for > additional damping over and above the natural > resonance distributing tapered shape & low res > characteristics of carbon composites. > > Igor > Nice, Igor. Good call. Steve Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 02:35:34 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com Thom wrote, in part: > For those of you who are not familiar with Linn's doctrine, they condend > that final cartridge bolt tightening should be performed with the arm off > the 'table in order to keep from putting unnecessary force on the bearings. > Linn is the only manufacturer I know of who issues this caution, so I don't > know how valid it is, especially for someone who doesn't exercize a gorilla > grip on the arm when tightening down a cartridge. Maybe with an arm like the Zeta, or perhaps Linn's own arms (which I know nothing about) this is a concern. I am sure the prudent person would have no problem tightening the cartridge bolts in situ on a mounted Rega. > > Another problem for Rega owners who do not adopt some form of VTA adjustable > base is the necessity of removing the arm in order to add or remove VTA > adjusting shims (ouch !). I'd definitely go for the adjustable base (Origin > Live's or a personal design) on any 'table I mounted a Rega. Ha! Not so, little grasshopper! Instead of using closed washers of shim material, splitting the shim into two halves, or with very thin shim stock, cutting the washer at one point will allow slipping shims in and out from the base by slightly backing off on the mounting nut. A lesson learned through experience (after removing the whole arm more times than I care to admit!) Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 19:47:09 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com I had similar thoughts to yours Steve. One probably only needs access to spin a Crescent wrench or large box wrench 90-120 degrees. Some kind of access slot facing the back of the table will suffice. One thing I didn't mention which makes this an issue with me is the comment in SP #10 about adjusting the belt tension when using something non-compliant such as recording tape or string. The correct tension is that which will spin the platter at the correct speed at the *lowest* voltage. With a rubber belt, this is a non-issue. If you have to move everything around everytime you access the arm, then adjusting belt tension is one more operation you have to perform. I'd like to end up with a design which doesn't require you to move the assembly. This obviously brings up the issue of how much mass allows the motor assembly to stay in place. Thom ----- Original Message ----- From: Steve Zettel To: Sent: Sunday, February 20, 2000 1:05 AM Subject: Re: [teres] Subchassis & Armboard on 2/19/00 19:41, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > Steve, > > Indeed, I don't think of carbon as being a silver bullet either. I hope I > didn't convey that. No, not at all. > > Speaking of context, I had a long conversation with Chris today about > tonearm mounting. > > We're trying to envision a mounting platform for the tonearm which does not > compromise rigidity, energy sinking, etc. and yet is aesthetic. I can see > why Verdier has that "tab" poking out on the right side of the 'table, but > I'm striving for something a bit more elegant looking. Two obvious > constraints to any design are access to (a) secure tonearm mounting as well > as for (b) arm cable routing. My Audiocraft arm has a big threaded tube and > a which passes through the armboard. A large nut secures the arm to the > armboard. One needs either a big socket to secure the nut or enough access > to use a big open end wrench. I believe that your Rega has similar mounting > issues. I am having the same conceptual problems. As you note, my Rega's require access to the mounting nut. I was considering several 1" thick rings of Corian, topped with a matching or contrasting slab drilled to accept the arm tube. Or maybe the top disc will be a frosted acrylic to match the cosmetics of the platter. Or maybe the arm towers will be completely acrylic. Anyway the bottom one or two would be more like hollow rings with a portion missing, oriented toward the back of the turntable, to allow access. I have been thinking about saving the missing segments and replacing them when access is not needed. A smaller hole drilled through the subchassis slab would allow the tonearm cables to exit underneath the subchassis (and sand). Glue would be one method for laminating the sections of acrylic or Corian together; another alternative (the high-tech look) would be to use stainless steel socket cap head bolts all the way through the subchassis and arm mounting towers. Let me know what you all think -- this group consistantly has better ideas collectively than spring up unassisted from my own imagination. Thanks, Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 19:50:23 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com I wondered why no one had mentioned split shims. I (stupidly) figured that there was something inherrently wrong with this concept and so never mentioned it. Goes ta show ya ... don't be shy & speak yer mind :-) On the subject of access to the bolt/arm fixing scheme, of course we still design easy access. Thom ----- Original Message ----- From: Steve Zettel To: Sent: Sunday, February 20, 2000 1:32 AM Subject: Re: [teres] Subchassis & Armboard Thom wrote, in part: > For those of you who are not familiar with Linn's doctrine, they condend > that final cartridge bolt tightening should be performed with the arm off > the 'table in order to keep from putting unnecessary force on the bearings. > Linn is the only manufacturer I know of who issues this caution, so I don't > know how valid it is, especially for someone who doesn't exercize a gorilla > grip on the arm when tightening down a cartridge. Maybe with an arm like the Zeta, or perhaps Linn's own arms (which I know nothing about) this is a concern. I am sure the prudent person would have no problem tightening the cartridge bolts in situ on a mounted Rega. > > Another problem for Rega owners who do not adopt some form of VTA adjustable > base is the necessity of removing the arm in order to add or remove VTA > adjusting shims (ouch !). I'd definitely go for the adjustable base (Origin > Live's or a personal design) on any 'table I mounted a Rega. Ha! Not so, little grasshopper! Instead of using closed washers of shim material, splitting the shim into two halves, or with very thin shim stock, cutting the washer at one point will allow slipping shims in and out from the base by slightly backing off on the mounting nut. A lesson learned through experience (after removing the whole arm more times than I care to admit!) Steve Z Subject: Re: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 20:05:56 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Sun, 20 Feb 2000, Thom Mackris / Joan Panzella wrote: > I wondered why no one had mentioned split shims. I (stupidly) figured that > there was something inherrently wrong with this concept and so never > mentioned it. Goes ta show ya ... don't be shy & speak yer mind :-) > > On the subject of access to the bolt/arm fixing scheme, of course we still > design easy access. We built a large and hefty dovetail slide, similar to the SME but much heavier. Into it goes a split sleeve which is internally threaded to fit the Rega arm pillar. Two set screw compress the threads of the sleeve into the threads of the arm pillar to firmly grasp it over most of its length. When loosened, rotation of the sleeve, adjusts the VTA. Kal Subject: [teres] Subchassis & Armboard Date: Sun, 20 Feb 2000 20:23:36 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: Teres_List All, I'm titling this subject based on the fact that I think that subchassis, armboard and motor mounting are an area which will be designed together as a coherent unit or subsystem. I had commented to Igor privately that it seems as if we should allow for periodic rotation of the motor so that the bushing wears evenly. If the motor "pod" is round, then we just rotate it a bit once a month. A small index mark (Perhaps painting one screw head a different color) would be helpful. On the first of each month, you rotate the motor one twelfth of a turn. Of course I listen to a whole lot more hi-fi in the Winter, so this complicates my scheme :-) If the motor is in a structure that can't be rotated, then the motor or it's mounting plate will have to rotated in order to expose a different part of the bearing to the radial load of the belt. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff To: Thom Mackris / Joan Panzella Sent: Saturday, February 19, 2000 8:32 PM Subject: Re: [teres] Motor/pulley/controller/supply "kit" My thoughts exactly. Might be a good idea to keep this in mind while designing the motor pod, in order to facilitate easy, *incremental* advancement of the position. Yearly rotation will not keep the bearing from developing ovalization of the bearings, and, once that pattern starts, it will be difficult to promote even wear because the original wear spot will act like a "detent", or a heavy spot unbalancing a wheel. If the motor pod is other than round, turning incrementally may not be possible, unless preparation is made for this, and the motor is mounted an a sub-plate, or some some system pre-thought out before building. I --- Thom Mackris / Joan Panzella wrote: [snip] > A side thought ... I guess that yearly, we might > want to rotate the body of > the motor 90 degrees to wear out the bushing evenly > over time. > Thom Subject: RE: [teres] Subchassis & Armboard Date: Mon, 21 Feb 2000 08:54:16 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Thom: I really don't have much experience with carbon fiber composites, so I don't have a feel for how they would sound. They are very strong, which may mean that they would be less inert than something like marble or constrain-layered MFD. Materials that are higher in tensile strength often tend to "ring" more, but that may not always be true. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Thom Mackris / Joan Panzella [SMTP:tmackris@earthlink.net] > Sent: Friday, February 18, 2000 11:53 PM > To: teres@aiko.com > Subject: Re: [teres] Subchassis & Armboard > > Steve, > > Did you check out that aerospace link that I forwarded earlier from Bill's > Joe List post? > > http://www.deltronix.com/public/acp/acp-ucfl.htm > > Carbon fiber plates and other stuff. I'd be curious in Ken's take on > this, > what with his structural engineering background ... the meaning of the > numbers. > > Thom > > > ----- Original Message ----- > From: steve brooks > To: > Sent: Friday, February 18, 2000 2:05 PM > Subject: [teres] Subchassis & Armboard > > > No one has mentioned and I know it would be expensive, but what about > carbon > fiber...maybe only for the armboard? Would there be any advantage in using > it for the subchasis? By the way it's expensive. But if we bought as a > group it would still be expensive. > Steve Brooks > > BTW, The mail list won't let me send my JPEG's so I'll ask Chris if he > wants > to put them on his website. > > Subject: [teres] Covers Date: Mon, 21 Feb 2000 12:34:16 -0700 From: phclark, phclark To: Teres I realize only too well that with the different implementations of this turntable there will likely be as many answers as participants, but here goes: My logistics may require that I have the 'table "out" in my living room, as opposed to inside a dedicated closet. I am concerned about a dust cover that doesn't require lengthy ritual, convenience is part of my musical enjoyment. There are numerous Plexiglas shops around that will happily charge me an arm and a leg for something of only average utility and less than average aesthetics. (This is my first real confrontation with the dreaded SAF.) Has anyone had any creative solutions to this dilemma? I don't mind the industrial look, personally, but I must keep the peace. (I'm having to execute new speaker cabinets for the living room,as well. She thinks 7.5 cuft apiece is, well, obtrusive.) Cheers, Peter C Subject: Fwd: [teres] Subchassis & Armboard Date: Mon, 21 Feb 2000 20:02:17 -0700 From: MaughanAudio@aol.com, MaughanAudio@aol.com To: teres@aiko.com Thom brings up a good maintenance point that one would also use for the platter bearing. Index it and rotate occasionally to increase life and reduce wear patterns. Subject: Re: [teres] Covers Date: Mon, 21 Feb 2000 20:49:12 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com Peter, I faced the same problem with my Merrill. I also had to protect it from 3 active cats. The Merrill is sitting on a low (18") Archi-Dee stand - it resembles the low welded Linn and Target stands. The Merrill does not come with a dust cover. Except for the absence of dustcover, it looks like a traditional turntable. My solution was to make a box out of MDF which surrounds the metal stand, coming up to the level of the shelf that supports the turntable - IOW, an 18" high box. There is a 1.5" ledge around the top of this sheath at the level of the turntable shelf. This box does *not* touch the turntable or stand in any way. I then fashioned (again out of MDF) a 4-sided box which resembles a plinth and is the same height as the Merrill's plinth. This fake plinth (or facade) sits on the above described lip - again, *not* touching the turntable in any way. I imbedded 4 screws in the bottom and there are corresponding dimples in the ledge to locate the "plinth" so it does not touch the real Merrill plinth. Both of these MDF parts are painted in faux granite (Fleck Stone - tm) although finishing options are obviously flexible. Prior to designing the above affair, I sourced a set of hinges and spec'd out a plexiglass dust cover which completes the look. The plexiglass dust cover cost about $25.00 from a local Phoenix plexiglass shop (yes, I lived in Phoenix in 1991). One note about hinges. Definitely source the hinges first. The most suitable hinge I found was one that required that the back of the plexiglass cover was open - in other words, the fake plinth was higher in the rear and ended up forming the rear of the dust cover. I hope I'm being clear here. I haven't figured out how to approach this problem with the Teres, since it will be an open chassis design and quite elegant looking - I want to protect it and yet not hide it. I might apply the same fake plinth / dust cover principle making having the bottom portion (the fake plinth in the above description) made of plexiglass. I need to integrate my thoughts into a stand design so that I don't have a drumhead transmitting vibrations to the turntable. My other thought on the matter is less involved - perhaps a lift off rather than hinged dust cover - one that will only be in place when I'm not listening. I have to give this some more thought. My thinking here is that the turntable will be out of the cats' line of fire (perhaps 40" tall) and will only be necessary when the system is powered down - this would certainly make things less complicated. I'm going to take this one slowly, although I have been obsessing about the solution. I had once made a high mass stand (250 lbs when sand filled) for a Sota that I previously owned. Unfortunately, I sold it when I learned that it didn't work with the Merrill. I now have to take on another project to build one. I'll make this stand the topic of another post. Cheers (more to follow), Thom ----- Original Message ----- From: phclark To: Teres Sent: Monday, February 21, 2000 11:27 AM Subject: [teres] Covers I realize only too well that with the different implementations of this turntable there will likely be as many answers as participants, but here goes: My logistics may require that I have the 'table "out" in my living room, as opposed to inside a dedicated closet. I am concerned about a dust cover that doesn't require lengthy ritual, convenience is part of my musical enjoyment. There are numerous Plexiglas shops around that will happily charge me an arm and a leg for something of only average utility and less than average aesthetics. (This is my first real confrontation with the dreaded SAF.) Has anyone had any creative solutions to this dilemma? I don't mind the industrial look, personally, but I must keep the peace. (I'm having to execute new speaker cabinets for the living room,as well. She thinks 7.5 cuft apiece is, well, obtrusive.) Cheers, Peter C Subject: RE: [teres] Teres-Motor&Supply/Shield&Damping Date: Mon, 21 Feb 2000 22:32:54 -0700 From: Scott Fraser, Scott Fraser To: teres@aiko.com the oil-lead shot is sealed in place with o-rings to avoid leakage or changes in the oil from evaporation or oxidation. >Mass helps, but something lossy in combination with the mass makes the >system perform much better. > >On our most critical optical components we use an old trick of filling a >chamber in the housing not with lead, but with lead shot and then filling >the space around that with light mineral oil. The dashpot action of oil on >the shot is great at eliminating the motions that mass alone would leave >behind.... > >Tested this on a Scheu and it is quiet. > >Scott > > > > > >= = = = = = = = = = = = = = = = = >Scott Fraser (sefraser@caltech.edu) >Caltech, Beckman Institute (139-74) >Pasadena, CA 91125 >626 395-2790 telephone >626 449-5163 fax Scott Fraser (sefraser@caltech.edu) Caltech, Beckman Institute (139-74) Pasadena, CA 91125 626 395-2790 telephone 626 449-5163 fax Subject: Carbon Fiber fact finding suprise! Date: Tue, 22 Feb 2000 18:51:21 -0700 From: steve brooks, steve brooks To: tmackris@earthlink.net; zettel@libby.org; gorkuz@yahoo.com; cbrady@sgi.com; kenschei@compuserve.com I promised to look into carbon fiber, so I figured why not start at the top and work my way down. So I called JD (or is it DJ?) Casser at Black Diamond Racing; makers of audiophile approved carbon fiber accesories. I really only called to ask him if this would be a good material for the application (he said it is the best of course!), and where to go for more info.... To my suprise he told me that he at one time was going to go about making different table parts out of carbon fiber...he has 3 Rega tables sitting in his office..2 to make changes to, and one to use a reference. He apparently does make custom armboards..he mentioned TNT's. He also said racing car guys who work with carbon fiber would have no idea how to help us, in fact he said he was the one who could! Anyway, he wanted more info, so I gave him Chris's website address and told him to check it out. He asked me to keep it quiet until he took a look at what we were doing, that's why I only mailed you guys. Oh and we didn't talk about price!! But I was shocked that he was so interested. Steve Subject: Re: Carbon Fiber fact finding suprise! Date: Tue, 22 Feb 2000 21:06:20 -0700 From: Steve Zettel, Steve Zettel To: steve brooks; tmackris@earthlink.net; gorkuz@yahoo.com; cbrady@sgi.com; kenschei@compuserve.com on 2/22/00 20:48, steve brooks at brookss@bellsouth.net wrote: > I promised to look into carbon fiber, so I figured why not start at the top > and work my way down. So I called JD (or is it DJ?) Casser at Black Diamond > Racing; makers of audiophile approved carbon fiber accesories. I really only > called to ask him if this would be a good material for the application (he > said it is the best of course!), and where to go for more info.... > To my suprise he told me that he at one time was going to go about making > different table parts out of carbon fiber...he has 3 Rega tables sitting in > his office..2 to make changes to, and one to use a reference. He apparently > does make custom armboards..he mentioned TNT's. He also said racing car > guys who work with carbon fiber would have no idea how to help us, in fact > he said he was the one who could! > Anyway, he wanted more info, so I gave him Chris's website address and told > him to check it out. > He asked me to keep it quiet until he took a look at what we were doing, > that's why I only mailed you guys. > Oh and we didn't talk about price!! But I was shocked that he was so > interested. > > > > Steve > > Very interesting. In my experience, there are some really helpful people out there, even among the "movers and shakers". Ron Welborne and Jonathan Carr immediately come to mind, as do Pierre Sprey (Mapleshade) and Harvey Rosenberg. One would hope that pricing would not be on the order of a similar mass of Racing Cones. . . Steve Z Subject: [teres] Carbon Fiber and You Date: Fri, 25 Feb 2000 23:03:07 -0700 From: steve brooks, steve brooks To: teres@aiko.com Well I promised to look into carbon fiber as a material for the base and/or armboard and here's what I found. I figured I would start at the top and I knew of only 2 companies in audio that dealt with carbon fiber: Wilson Benesch and Black Diamond Racing. BDR was in the closest time zone so I tried them first. I talked to DJ Casser at BDR...he may be the only guy at BDR, I don't know, and asked him where I could go for info and what kind of place I should check out for manufacturing and here's what he said: First off, he said the application is a good one for carbon fiber...according to him it's the best thing (of course he makes his living selling the stuff so take it for what it is). He has sold armboards made out of carbon fiber for some folks...and the feedback was very positive...sexual was the word he used... He also told me not to waste my time with racing manufacturers..they wouldn't have a clue as to what we needed...he told me he was the guy to make what we needed! It turns out he's toyed with doing something with turntables for a while and has never gotten to it. (apparently he has 3 Rega's sitting on his office floor for experimentation). Also he kept saying this project would fit nicely with a project that was upcoming for BDR...but he didn't seem to want to talk about what it is.. Anyway, he's looked at the website and he's interested. If we give him some measurements he'll work up some prices. Now I have no idea what kind of money we are talking about, but I sure would like to know...what if we gave him the measurements for the simple rectangle base and way cool curved armboard that Ghris first drew up? Although I love the second drawing the top one would probably be alot cheaper to produce. What do ya's think? Steve Subject: Re: [teres] Carbon Fiber and You Date: Fri, 25 Feb 2000 23:36:59 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Good start, Steve, Obviously the price issue will be pivotal in this. Personally, I am most impressed with what carbon fiber does with vibration in racquetball racquets. And my elbows (both, I was forced to learn to play lefty while my right was out for more than four months at one point due to vibration/shock) heartily endorse carbon fiber. After changing to a c.f. racquet (pricey for a good one, but worth every penny), no more problems, a number of years, trouble free. How much this translates to what my ears will think of carbon remains to be heard, but the prognosis is pretty hopeful. C.f. does seem to be quite good with vibration. I've heard a c.f. headshell compared to a metal one, and the difference was certainly apparent, that is, notably superior. I am indeed curious to discover if carbon fiber will keep our turntables "regular". Igor --- steve brooks wrote: > Well I promised to look into carbon fiber as a > material for the base and/or > armboard and here's what I found. > I figured I would start at the top and I knew of > only 2 companies in audio > that dealt with carbon fiber: Wilson Benesch and > Black Diamond Racing. BDR > was in the closest time zone so I tried them first. > I talked to DJ Casser at BDR...he may be the only > guy at BDR, I don't know, > and asked him where I could go for info and what > kind of place I should > check out for manufacturing and here's what he said: > First off, he said the application is a good one > for carbon > fiber...according to him it's the best thing (of > course he makes his living > selling the stuff so take it for what it is). He has > sold armboards made out > of carbon fiber for some folks...and the feedback > was very positive...sexual > was the word he used... > He also told me not to waste my time with racing > manufacturers..they > wouldn't have a clue as to what we needed...he told > me he was the guy to > make what we needed! > It turns out he's toyed with doing something with > turntables for a while > and has never gotten to it. (apparently he has 3 > Rega's sitting on his > office floor for experimentation). Also he kept > saying this project would > fit nicely with a project that was upcoming for > BDR...but he didn't seem to > want to talk about what it is.. > Anyway, he's looked at the website and he's > interested. If we give him > some measurements he'll work up some prices. > Now I have no idea what kind of money we are > talking about, but I sure > would like to know...what if we gave him the > measurements for the simple > rectangle base and way cool curved armboard that > Ghris first drew up? > Although I love the second drawing the top one would > probably be alot > cheaper to produce. > What do ya's think? > > Steve > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 01:25:14 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com Steve, I am also leaning toward the simpler concept that Chris "drew" even though the "scalloped / 4 poster" version looks way cool. I think I share your reasoning here. The armboard would be simpler and have a lot more mass. Here are some thoughts I'm having with respect to the armboard: Premise: The top of the armboard needs to be approx. 1" to 1/14" below the level of the platter in order to allow proper VTA adjustment (cross-validate this with your tonearms folks). Known dimensions: The level of the platter surface is from 3-1/8" to 3-1/4" above the level of the subchassis. The platter is 3" thick and clears the subchassis by either 1/8" or 1/4" depending on whether or not you opt for a 1/8" thick washer between the bearing and subchassis. Therefor: The armboard needs to raise the tonearm approximately 2" above the subchassis. I'd love to know what the following two options would cost in carbon ... (1) Make this entire 2" block into a removable armboard. The area where the arm actually mounts will have to be reduced to approx. 1" in order to mount the arm. In this case, the dimensions are approximately 2" thick, 3-1/2" wide, and 14" deep. the rear 4" or so would have to be reduced to 1" thick to accomodate tonearm mounting. (2) Make a fixed portion which attaches to the turntable that is 1" thick, and a removable 1" thick piece that bolts onto the lower piece. This removable armboard could either run the entire length of the lower piece or it could be 1/2 length. In the short version, we should allow for 3-4 bolts to cinch the armboard down. In the full length version, I'm guessing 6 bolts would be safe. If the board is partial length, then the lower mounting area can be a full 2" high on the front half, so when the armboard is mounted, the entire affair is a flush (or nearly so) surface. So: assuming a removable armboard either 1/2 or full length removable 1" thick armboard, we have a rough idea of size: A rectangular piece of carbon fiber that's 1" thick, 3.5" wide and either 7-1/2" or 15" long. If we want to get fancy, the right rear corner can be radiused. Cheers, Thom ----- Original Message ----- From: steve brooks To: Sent: Saturday, February 26, 2000 12:58 AM Subject: [teres] Carbon Fiber and You Well I promised to look into carbon fiber as a material for the base and/or armboard and here's what I found. I figured I would start at the top and I knew of only 2 companies in audio that dealt with carbon fiber: Wilson Benesch and Black Diamond Racing. BDR was in the closest time zone so I tried them first. I talked to DJ Casser at BDR...he may be the only guy at BDR, I don't know, and asked him where I could go for info and what kind of place I should check out for manufacturing and here's what he said: First off, he said the application is a good one for carbon fiber...according to him it's the best thing (of course he makes his living selling the stuff so take it for what it is). He has sold armboards made out of carbon fiber for some folks...and the feedback was very positive...sexual was the word he used... He also told me not to waste my time with racing manufacturers..they wouldn't have a clue as to what we needed...he told me he was the guy to make what we needed! It turns out he's toyed with doing something with turntables for a while and has never gotten to it. (apparently he has 3 Rega's sitting on his office floor for experimentation). Also he kept saying this project would fit nicely with a project that was upcoming for BDR...but he didn't seem to want to talk about what it is.. Anyway, he's looked at the website and he's interested. If we give him some measurements he'll work up some prices. Now I have no idea what kind of money we are talking about, but I sure would like to know...what if we gave him the measurements for the simple rectangle base and way cool curved armboard that Ghris first drew up? Although I love the second drawing the top one would probably be alot cheaper to produce. What do ya's think? Steve Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 08:23:41 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Fri, 25 Feb 2000, steve brooks wrote: > Well I promised to look into carbon fiber as a material for the base and/or > armboard and here's what I found. Interesting. For a tangential thought, take a look at this site for bases: www.silentrunningaudio.com Kal Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 08:45:11 -0700 From: steve brooks, steve brooks To: teres@aiko.com Thom, Ok but what about the chasis? He's willing to price that also. Is it overkill to make a chasis out of cf... What do we need the chasis to do? Stop any vibration that the bearing produces from getting to the armboard..keep the armboard from any motion...isolating everything as much as possible from the outside environment...is this too simple a description... Steve > (1) Make this entire 2" block into a removable armboard. The area where the > arm actually mounts will have to be reduced to approx. 1" in order to mount > the arm. > > In this case, the dimensions are approximately 2" thick, 3-1/2" wide, and > 14" deep. the rear 4" or so would have to be reduced to 1" thick to > accomodate tonearm mounting. > > (2) Make a fixed portion which attaches to the turntable that is 1" thick, > and a removable 1" thick piece that bolts onto the lower piece. This > removable armboard could either run the entire length of the lower piece or > it could be 1/2 length. In the short version, we should allow for 3-4 bolts > to cinch the armboard down. In the full length version, I'm guessing 6 > bolts would be safe. If the board is partial length, then the lower > mounting area can be a full 2" high on the front half, so when the armboard > is mounted, the entire affair is a flush (or nearly so) surface. > > So: assuming a removable armboard either 1/2 or full length removable 1" > thick armboard, we have a rough idea of size: > > A rectangular piece of carbon fiber that's 1" thick, 3.5" wide and either > 7-1/2" or 15" long. If we want to get fancy, the right rear corner can be > radiused. > > Cheers, > Thom > > Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 09:03:48 -0700 From: steve brooks, steve brooks To: teres@aiko.com > On Fri, 25 Feb 2000, steve brooks wrote: > >> Well I promised to look into carbon fiber as a material for the base and/or >> armboard and here's what I found. > > Interesting. For a tangential thought, take a look at this > site for bases: www.silentrunningaudio.com > > Kal > > Very nice craftsmanship...a little light on details...how can they isolate in both planes without air? Have you had a chance to hear them Kal? Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 09:38:34 -0700 From: Kalman Rubinson, Kalman Rubinson To: teres@aiko.com On Sat, 26 Feb 2000, steve brooks wrote: > Very nice craftsmanship...a little light on details...how can they isolate > in both planes without air? Have you had a chance to hear them Kal? They have a complex construction including "our proprietary laboratory developed, chemical damping materials" supporting an internal 'raft.'> No, I have not 'heard' them. They come highly recommended. Kal Subject: Re: [teres] Carbon Fiber and You Date: Sat, 26 Feb 2000 11:38:00 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com I suppose it doesn't hurt to have him price it out. I'm scared at the numbe$ which will come back, based on the price of a 3 BDR tiptoes (which I own and like, BTW). One thing for sure, due to use of carbon, it won't have to be 3" thick as drawn. Say 1.5" to 2.0" ?? I would think that he could give an off the top of the head estimate based on the picture? If not, we can come up with more detailed dimesnions. These drawings were just concept drawings to get the ball rolling. Thom ----- Original Message ----- From: steve brooks To: Sent: Saturday, February 26, 2000 10:20 AM Subject: Re: [teres] Carbon Fiber and You Thom, Ok but what about the chasis? He's willing to price that also. Is it overkill to make a chasis out of cf... What do we need the chasis to do? Stop any vibration that the bearing produces from getting to the armboard..keep the armboard from any motion...isolating everything as much as possible from the outside environment...is this too simple a description... Steve > (1) Make this entire 2" block into a removable armboard. The area where the > arm actually mounts will have to be reduced to approx. 1" in order to mount > the arm. > > In this case, the dimensions are approximately 2" thick, 3-1/2" wide, and > 14" deep. the rear 4" or so would have to be reduced to 1" thick to > accomodate tonearm mounting. > > (2) Make a fixed portion which attaches to the turntable that is 1" thick, > and a removable 1" thick piece that bolts onto the lower piece. This > removable armboard could either run the entire length of the lower piece or > it could be 1/2 length. In the short version, we should allow for 3-4 bolts > to cinch the armboard down. In the full length version, I'm guessing 6 > bolts would be safe. If the board is partial length, then the lower > mounting area can be a full 2" high on the front half, so when the armboard > is mounted, the entire affair is a flush (or nearly so) surface. > > So: assuming a removable armboard either 1/2 or full length removable 1" > thick armboard, we have a rough idea of size: > > A rectangular piece of carbon fiber that's 1" thick, 3.5" wide and either > 7-1/2" or 15" long. If we want to get fancy, the right rear corner can be > radiused. > > Cheers, > Thom > > Subject: Re: [teres] New to the club Date: Mon, 28 Feb 2000 10:48:06 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Hi, Daus, Welcome. I, too, believe that springs are not good for much of anything in audio beyond making amusing "Boinnnng" sounds for punctuating slapstick humor. I have learned this repeatedly, in numerous & varied applications. They are simply too resonant, with too little internal damping, and sing (read "zzzing") on more frequencies than their designed fundamentals. The "ol' Dual" I've been mentioning did not do its best despite all that I had done to it until I put it on an air suspension. The (compression) springs of its suspension, despite mechanical damping, may as well not have been there , for the collateral problems they created. I even found that replacing the little springs of a CD transport bearing tensioner with simple rubber bands plus weights resulted in an audible improvement, believe it or not. I've come to think that just about anywhere I see metal springs in an audio system, a benefit can be gleaned just by changing to air or rubber, or some other viscoelastic material with better internal damping. Anything but "boingers", anyway !! Igor --- Thom Mackris / Joan Panzella wrote: > Welcome Daus, > > Indeed, we are of like minds with respect to spring > suspended subchassis > design. You have found your way home! I think that > a suspended subchassis > is a fine compromise when the designer can't predict > the stability of the > floor and or stand, but in when one is assaulting > the state of the art, a > stable motor/belt/platter interface is indeed > hampered by such an > architecture. > > BTW, I started on this project with Chris, thinking > that I'd be hard-pressed > to match my Merrill turntable. It sounds as if > we've traversed similar > paths with our current analog rigs. As the project > has unfolded, I've > become gung-ho to surpass it my Merrill! > > Cheers, > Thom > > > ----- Original Message ----- > From: Daus Studenberg > To: > Sent: Sunday, February 27, 2000 3:24 PM > Subject: [teres] New to the club > > > Hi everyone, > I managed to subscribe to the list and I am also > going to be the recipient > of the Teres platter. This is going to be an > exciting project and I look > forward to working with the group. A little about > myself: I am working on > my last year at the University of Florida in > Mechanical Engineering. I am > specializing in vibrations and acoustics. I am an > audio DIY hobbyist and my > projects include ME-2's (smaller ariels), a van > alstine modified St-70 and a > fully modified AR-XB turntable. The turntable was a > great learning > experience as I fitted it with an acrylic platter > and subchassis,cherry wood > sides and a grace 707 MK-II tonearm. I learned a > lot from it in that > suspended chassis designs aren't great (with springs > at least) in that they > still transmit sound and hamper the > motor-belt-platter interface. Brute > mass, damping and rigid tonearm/platter interface > was the way to go and > that's why I like the Teres project! :) Anyway, I > just wanted to comment > on the belt pulley assembly design. Based on my > experience with the AR > turntable, I found that the flat belt design was the > best. The pulley MUST > have a convex edge as it keeps it centered to > prevent it from traveling up > and down. The Basis uses that design. I also > believe that we do not have > any grooves on the side on the platter so the flat > belt approach is the only > way to go. Besides, I hear we are having a really > precise motor system and > a flat belt system would help reduce the speed > errors between the platter > and the motor. A thin round belt would only > increase the error. I also > think the metal-friction fit design would be the > best to reduce wear and > keep costs low. I hope I didn't take up too much > bandwidth! Thanks, Daus > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: [teres] Subchassis Design Layout Date: Tue, 29 Feb 2000 13:36:10 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'Teres_List' All, Here are my current thoughts on subchassis design... very art deco / Frank Lloyd Wright'ish. I haven't thought through the materials yet, although in the interest of economy, I think that they will be either all acrylic, or a combination of acrylic & MDF. The top layer will most definitely be acrylic or something else that's stiff. I'm favoring rigidity over outright damping, because it seems to me that damping can always be addressed later (i.e. a sandbox, or whatever). You can't go back and stiffen up the structure too easily after the fact. This was done in Paint and is therefor not to scale. The 5 layers are intended to be 3/4" thick each. The two armboard pieces will most likely be 1" thick each, raising the tonearm mounting plane to somewhere between 1-1/8" and 1-1/4" below the record playing surface. This range takes into account the optional 1/8" washer mounting between the bearing and the subchassis. I'm envisioning a rectangular block cut out ot the subchassis at the tonearm mounting area (the right rear corner) to allow access for mounting the arm and routing the cable. The lower of the two tonearm blocks will also extend only to this cutout. The top piece (the actual armboard) will extend just far enough back to allow for a good mounting surface for the arm - no sense adding an extra 1" or so of acrylic where it can only serve to flop around. Thom <> --------------------------------------------------------------------- Name: subchassis.jpg subchassis.jpg Type: JPEG Image (image/jpeg) Encoding: base64 Subject: RE: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 14:01:19 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; 'teres@aiko.com' I think the round plate is the way to go, but if it's 1/4 inch thick a motor recess is necessary so that the pulley can be mounted close as possible to the motor. Right now my vision for the Teres would be similar to the Simon York design, using a small circular subchassis and a small arm board for increased immunity to airborne and support vibrations. I think smaller is better for this design given the use of derin for the thrust bearing, this should offer low noise without the need for a large vibration sink. I'm thinking of using 2 to 2.5 inch thick x 7 to 8 inch dia. brass or stainless steel for the subchassis, maybe sandwiched with Soundcoats CN material. But this could all change the more I think and learn from you guys. Thanks guys, Stan At 11:36 AM 2/29/2000 -0700, Mackris, Thom G. wrote: >Although I am gravitating toward a big honkin' rectangular motor/controller >"block" much like Chris' first POV ray drawing and the Amazon Reference >'table, I can see a real benefit to a circular plate. > >A circular plate would facilitate periodic rotation to facilitate equal wear >on the motor bushing. If the holes (8 to 12) were drilled via CNC, we'd be >guraranteed that they were symetrical and could be mounted in more than one >orientation. The idea of 1/4" thickness or greater is appealing from a >rigidity standpoint. I'll bet we're talking about only $15 per unit in the >quantities we'd be ordering (a guess). > >Cheers, >Thom > >-----Original Message----- >From: Chris Brady [mailto:cbrady@sgi.com] >Sent: Tuesday, February 29, 2000 10:29 AM >To: teres@aiko.com >Subject: [teres] Motor/supply kit > > >I am wondering if there would be interest in including >a motor mounting plate in the motor/controller kit. >I expect that there will be a lot of different shapes and >sizes of motor pods, but perhaps we can agree on a single >mounting plate design and benefit from a quantity discount. > >I am thinking that a round mounting plate, say 4" in diameter >with mounting holes around the edge would work for either a >round or rectangular motor pod. We could each make our own >but with enough units they could be precision made on a NC >mill at a reasonable cost. If made from fairly thin aluminum >(1/16 - 1/8") it would be inexpensive. However, we could >also opt for a more expensive design made from 1/4 - 3/8" >aluminum with nice recessed holes for cap screws and an >anodized finish. The thicker plate may not work any better >but it would sure look sweet. > >Chris > Subject: Re: [teres] Motor Pod Date: Tue, 29 Feb 2000 15:03:42 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com All, Following the various factors & solutions discussed pertaining to motor pod design & implementation, I had yet another thought for consideration. I suppose some of you wish I would run out of them by now, but I can't help it. This concerns the underpinnings of the pod. While I am sure that we will end up with a variety of techniques employed, I would like to suggest a novel configuration which would probably not normally be considered. What I have in mind is pursuant to my previous suggestion that there should be enough compliance in the motor/platter axis to allow a belt tensioning scheme to do its thing unhindered, so that it can be repeatably calibrateable. My suggestion today is to place the motor pod on two, yes two, not three (much less four) cones. [Double your pleasure/Double your fun/with two cones, yes *two* cones on one…(axis) (viz. : Pretty twins holding two motor pods) ] Wouldn't this just fall over? Well, yes, if you tried to stand this up by itself. To this end , something like slightly shorter "training wheel" feet of some sort could be added on the cross-axis, for convenience during setup, or disuse. If, however, in use, this was balanced (adding a simple, inexpensive bubble level to the top of the pod would be a good idea), and the belt slipped on, and the belt tensioning set, this rig will stand up nicely, and, this being the important thing, *belt tension will now be dependent only on the tensioner setting*. Additionally, concentrating the weight upon just two cone points, not three or more, couples the pod to the surface it sits on even better. Should you not want this tight coupling to implement your personal technical philosophy, or layout combinations, just use something compliant instead of the two cones. Finding the balance points for placing the cones is simple enough. If your pod is symmetrical, this is obvious, just use the centerline. If it is not , due to the layout of switches, power supply, whatever, just set the completed pod, minus the balancing weight (if you go that route, which I suspect would be the most popular for its simple neatness, not mention the adaptability of old tonearms & their weights) on a dowel or something like that along the expected balance axis. play with it until it balances neatly, mark the location, & mount the cones, or whatever, on that line. I would suggest exiting the wiring on the centerline somewhere to maintain balance. To sum up what could be the ideal pod setup: The scheme outlined above, a belt tensioner rig, a voltmeter for setting the actual tension, a rotateable motor mounting plate, a massive pod designed to dissipate vibration, and a lightweight metal pulley with dual profiles. The belt, if flat, should have a half twist. Feel free to add anything I've left out. A thought about using the voltmeter might be worthwhile at this point. As the idea has been running so far, it is assumed that the lowest voltage reading would correlate to the lowest tension useable, and that would be the ideal setting for belt tension. I disagree with that. I suspect that at that lowest tension we would be running at the onset of slippage, which would be very difficult to determine, quantify, or even pin down sonically by ear, and this would be an unwise condition. I posit that it would be a better regimen to find that lowest point, and increase tension bias to just a bit above that to guarantee the smoothest power transfer. Igor __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: [teres] FW: Teres and carbon fiber Date: Tue, 29 Feb 2000 15:28:05 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'Teres_List'; 'Steve.Brooks@turner.com' All, Steve asked me to forward the attached e-mail to the list, as he's not subscribed from his work e-mail. Thanks for doing the research, Steve. You might want to first read Steve's post at the end of this e-mail before reading my comments which immediately follow. Thom's comments .... With all fairness to DJ Casser, and respecting that he's in business to make money, my original thoughts when you reported on his offer to mold lots of carbon for us was that this was a great business opportunity for him. Take this in light of the fact that I own and love his racing cones under my BAT preamp. I respect the fact that he's not inclined to give away any proprietary information, but his comments don't really give us any new information and certainly don't address any issues that this design hasn't already accounted for. Had the collective knowledge of this group not been through this rigorous design exercise, I might be inclined to sign him up for some of his design talents, but after the fact, I'd have to humbly say that perhaps he should be hiring us for advice :-)) Addressing the issue of a bare acrylic platter, we had discussions early on about the record/platter surface. Two main schools of thought emerged: (1) There may be some who chose to experiment with various mat materials (2) Imperfect clamping may be the reason that DJ reported a bright sound with bare acrylic. My Merrill has a thin coating of lead on top of acrylic. I would expect this to sound similar to acrylic as far as "brightness" is concerned, and yet my Merrill is very well damped, considerably less "ringy" than the average unclamped, felt mat, Linn LP12. The Merrill has a periphery clamp which results in the entire record being in good contact with the platter. The Oracle and VPI use a reflex clamp (a washer on the spindle, under the record in combination with a center clamp that exerts downward pressure at the edge of the record label). The Well Tempered takes the reverse approach by dishing a concavity into the plater in conjunction with a flat clamp. All three of these methods address the problem of flattening out the record to make good contact with the platter without using vacuum, albeit slightly differently. I'm sure we've left ourselves with plenty of options as far as optimizing the record/platter interface and reducing the ringing that DJ reports having experienced. With all due respect to DJ Casser, I have to wonder what variables he was controlling when he worked with varying platter and subchassis thicknesses. Was the thrust surface of the bearing up to the task of a heavier (thicker) platter? Was the geometry of the bearing optimized to reduce the "teeter-toter" effect of so much mass? With respect to a thick, carbon fiber subchassis and armboard sounding harsh - I'd be interested to see what else changed at the same time. Most likely, the thick armboard was accompanied by the thicker platter (to raise the tonearm to the correct playing height) - see above comments about thrust plate & teeter-totter. I'll bet he beefed up the subchassis at the same time he went to a thicker platter (thinking he needed to support the extra mass of the platter without flexing). Perhaps he actually **improved** the resolution of the system and was now hearing an **inferior** bearing, bearing-platter geometry or motor/controller. The possibilities are indeed endless, but the good news is, I believe we have all of our bases covered as far as allowing room for experimentation. I appreciate your research and his offer to help, but in the absence of a complete story, his comments don't really help us much or tell me that we're headed in the wrong direction. They do confirm that we will be experimenting :-) BTW, the threaded area of the bearing will accomodate any thickness subchassis we choose, from approx 3/4" to approx 2 -1/4". We specifically allowed for choice and experimentation here too. We can experiment to the point that we never end up listening to music :-)) If one wanted a ridiculously thin subchassis (thinner than 3/4" !!!) for some insane reason, one could insert a couple of spacers on the top of the subchassis. Hell, we could have this baby flopping in the breeze if we chose :-)) Thanks again for doing the research, Thom Steve's post follows ... -----Original Message----- From: Brooks, Steve [mailto:Steve.Brooks@turner.com] Sent: Tuesday, February 29, 2000 1:31 PM To: 'Mackris, Thom G.'; 'brookss@bellsouth.net' Subject: Teres and carbon fiber Thom, can you post this to the mail list..I'm at work and am only subscribed at home. thanks, Steve I spoke to DJ Casser today about the Teres and it seems my earlier optimism about his involvement was misplaced. He did not realize that our design for the bearing and platter were finalized. How does the platter and bearing effect the chassis and armboard? Here's the scoop in his words: >1. we have found the thickness of our materials are critical to >the sonic >performance. 2" is way too thick: will sound harsh. Been there, >Done that. >2. same for the armboard. So because our bearing is so long and our platter so tall, carbon fiber would not be a wise choice. Oh well. He also expressed some concern over a 3" acrylic platter...his words again: >the acrylic platter should have some damping material of some sort >implanted [lead, etc]. acrylic by itself will sound bright. I realize this is a little late in the game, does anyone have any idea if this could be accomplished later? He told me you would need a big lathe (15"?) to drill the holes, as they would need to be perfectly balanced. Anyway he is a really nice guy who is very forthcoming. We just got to him a little late in the game. Now how about Corian? Steve Brooks Subject: Re: [teres] Subchassis Design Layout Date: Tue, 29 Feb 2000 20:39:22 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com I like this multiple layer idea very much as I have been considering it myself. We need a good rigid,dense and energy absorbing sheet for the arm/platter coupling. I have come across a sample four months ago in a vibrations class that was a sheet of material that had a high acoustic transmission loss. This board appeared to be 1" thick made from acrylic and lead powder! It was also rigid as well. But for the time being, I am considering the design that uses multiple layers for a constrained damping type resonance control. I have been looking at a company that sells damping sheets, mainly the vinyl type. So here is my design: one inch thick sheet of acrylic -vinyl sheet - 3/4"mdf - vinyl sheet - 3/4"mdf - vinyl sheet - 3/4" acrylic. Its close to being 3.75" thick and I may add another layer. After I glue the pieces together and cut the final block, I will cover it with paper backed veneer. I am a bit worried about the acrylic/glue combo, but this is my tentative plan. I plan on this idea to be extremely resistant to acoustically induced vibrations. I am also assuming little floor induced vibrations though a granite - sandbox approach. The thing I am most concerned about in the design is whether or not I can veneer to acrylic and whether or not my table saw will be "happy" with cutting through MDF/vinyl/acrylic!! Daus > Here are my current thoughts on subchassis design... very art deco / Frank > Lloyd Wright'ish. > > I haven't thought through the materials yet, although in the interest of > economy, I think that they will be either all acrylic, or a combination of > acrylic & MDF. The top layer will most definitely be acrylic or something > else that's stiff. I'm favoring rigidity over outright damping, because it > seems to me that damping can always be addressed later (i.e. a sandbox, or > whatever). You can't go back and stiffen up the structure too easily after > the fact. Subject: Re: [teres] Subchassis Design Layout Date: Tue, 29 Feb 2000 21:12:10 -0700 From: Thom Mackris / Joan Panzella, Thom Mackris / Joan Panzella To: teres@aiko.com Hi Daus, We're moving toward convergance in an area where I expected the design principles & philosophies to vary much more than they have. Certainly, aesthetics will come into play as we envision our ultimate analog altar :-) For example, the staggared design doesn't sound as if it suits your tastes. Gordon Maughan is an advocate of sculpting away excess mass in the subchassis, somewhat like Chris' "4 poster" design on the web page. I can't wait until we're all finished with this project to see all of the different interpretations on a subchassis. One appealing aspect of the "staggared" design I put out to the list earlier today is that the pieces will be cut separately - I'd order 3 rectangles (15" x 19") and 2 rectangles (14" x 18"). The only cutting would be the corner in the back to facilitate tonearm mounting access / cable routing. This could be easily done with a router, one piece at a time. During assembly, one would obviously be very careful in lining up the pieces, but I could sleep easily if I got the pieces to within 1/32". This lead/acrylic combo is a facinating material. I gather you don't know much more about it. In several offline conversations, we're coming to an agreement that rigidity should be the first consideration and damping second - the reason being that you can come back and damp later where it's next to impossible to make the subchassis more rigid at a later date. Obviously we don't have to take this to an extreme - we don't want something that rings like a bell, in search of rigidity, but you get my point. Sand and/or sorbothene ought to do just fine for damping after the fact. Cheers, Thom ----- Original Message ----- From: Daus Studenberg To: Sent: Tuesday, February 29, 2000 10:40 PM Subject: Re: [teres] Subchassis Design Layout I like this multiple layer idea very much as I have been considering it myself. We need a good rigid,dense and energy absorbing sheet for the arm/platter coupling. I have come across a sample four months ago in a vibrations class that was a sheet of material that had a high acoustic transmission loss. This board appeared to be 1" thick made from acrylic and lead powder! It was also rigid as well. But for the time being, I am considering the design that uses multiple layers for a constrained damping type resonance control. I have been looking at a company that sells damping sheets, mainly the vinyl type. So here is my design: one inch thick sheet of acrylic -vinyl sheet - 3/4"mdf - vinyl sheet - 3/4"mdf - vinyl sheet - 3/4" acrylic. Its close to being 3.75" thick and I may add another layer. After I glue the pieces together and cut the final block, I will cover it with paper backed veneer. I am a bit worried about the acrylic/glue combo, but this is my tentative plan. I plan on this idea to be extremely resistant to acoustically induced vibrations. I am also assuming little floor induced vibrations though a granite - sandbox approach. The thing I am most concerned about in the design is whether or not I can veneer to acrylic and whether or not my table saw will be "happy" with cutting through MDF/vinyl/acrylic!! Daus > Here are my current thoughts on subchassis design... very art deco / Frank > Lloyd Wright'ish. > > I haven't thought through the materials yet, although in the interest of > economy, I think that they will be either all acrylic, or a combination of > acrylic & MDF. The top layer will most definitely be acrylic or something > else that's stiff. I'm favoring rigidity over outright damping, because it > seems to me that damping can always be addressed later (i.e. a sandbox, or > whatever). You can't go back and stiffen up the structure too easily after > the fact.