Damping Platter With Liquid Latex

[Ldg]

no worries, Victor, if I have 'done wrong', then we must put it right. You, and others know that I am not about making a quick buck (slow ones, yep! ) and would rather help someone with a problem I can help with for nowt

Putting it right sounds good to me, CS. If you have commercial intent or ambition in this area, just be up front about it. If not say it straight. Because surely that would be a declarable interest, and it's the decent thing to do.

For example, would you disclose how we might make these damping materials for ourselves to test ? That would be useful and interesting. How else is one supposed to lay hands on it..........!?

I suppose that's an acid test of philanthropy's extent ...........we'll see.

I can empathize with Luckdog, as trying to get things across which are not obvious, or contrary to ones beliefs, is not easy, don't I know it! I do support ld in his quest to get things correct, its just the way of going about it which is a bit of a struggle.

Just read the content of my posts, CS, and decide whether they are true, or plausible. I'm not asking anyone to share a flat here, just discuss the content of my posts ! Where they are wrong, or debatable, challenge them. All too often responses are ad hominem. Which I find objectionable and tedious as much as anybody. I trust you might also empathise with how I might find the matter at issue irksome, more so than most here perhaps.

[Eoin]

One of the nice things (normally) about the Vinyl Engine forum is that this type of thing doesn't often happen here. Waste of a good topic this one.

If we can't discuss a simple enough issue such as this without throwing rocks then it's not good.

Well I've learned a couple of things anyway. Still got a lot of questions!

But not on this thread. Perhaps another day.

I'm out too. See ya!

[Ldg]

Well I've learned a couple of things anyway. Still got a lot of questions!

Yes, there are one or two gems that are thought provoking. Such as why CS does not observe the platter resonance fundamental during normal replay, but does when the platter is struck during replay............? I will have to try this. It could just be a matter of level, of course.

[Eoin]

Yup. This leads to the question of whether you want to try damping a platter or not. It might ring like a monk's bell when struck but does this actually matter? Not so easy to say.

A question for another day.

[Ldg]

It might ring like a monk's bell when struck but does this actually matter? Not so easy to say.

A question for another day.

Yes, it actually needs quite a bit of thought, and verification. I mean, it really should matter...........so why apparently not ?

Another day.

[cafe latte]

Hello,

No Cat,never come across a deck with factory made damped platter,apart of course from glass , MDF or acrylic platters.

Take the Garrards 401/301 platters,unless fitted with the now famous rubber ring they act like a bell.Never quite sure that a platter needed damping and as I said before I doubt whether any DIY damping could be done precisely enough not to interfere with balancing.

Over on LH plenty members advocate platter stacking but,so far,no one has written about what checks were made regarding balancing after stacking. May as well turn your own platter and hope for the best.

Cat,I may need your help with an Ortofon SMG212 and my new purchase,a grease bearing 301. Will send you a PM.

Hope all's well my friend.

Regards,

Victor.

Interestingly (if anyone is still here ) My Commonwealth electric had what I thought was a rubber damping ring round the platter, but to my suprise when I removed it for painting the platter it turned out to be a lead ring! Is this good or bad as a damping ring?
Also my Commonwealth has a shield round the motor which many Commonwealths do not (maybe a late model mod). IMO it is to either electrically shield the motor or to help cause a vortex and aid cooling, but IMO due to it being thin metal will ring so I put a large rubber ring round it which seems to deaden it. Again does this sound reasonable.
Regards
CL

[vincitsemper]

Hey Caffe latte,

A lead ring around a platter? Interesting,do you still have it?

I work with lead a lot and have used it in the past to try filling the void under the Gl75 chassis.I have also made a platter mat for a B52 in order to increase mass and try making the stamped steel platter less attracted to cartidges.

Never known a platter to have a lead ring around it but I suppose it would work as lead is a dead sounding metal at the best of times.

If you still have it it would be great to see photos,lead would get easily damaged though so probably would not look that good after a few years of knocks and scratches.

Regards,

Victor.

[Ldg]

Hi CL. An obvious primary purpose for a lead rim band is to add inertia. On the other hand, lead has an exceptional loss factor for a metal, orders of magnitude higher than other common metals. So it also makes a very good lossy damping material. Rim band of that nature is likely to be highly effective damping some platter vibration modes, perhaps complimentary to conventional mat damping ?

Perhaps its a 2fer ?!

[cats squirrel]

I would agree with ld about the inertia, for lead is very poor at damping. The damping factor figure I obtained was 0.032, and whilst it is three times better than copper or brass, it is still a miserable material to use for damping, despite what may have be said in books, magazines and on forums.

There are a lot of myths spun in mags and on forums, and ringing platters seems to be one of them. Sure, if you hit a metal platter (or glass etc.) it will ring, but what relevance is that if it can't be detected by a stylus playing a record.

So the inference would be, if one wants to lessen the ringing in the platter (for peace of mind) then a little damping material will probably help, but if one wants to damp it sufficiently, one will have to use an awful lot of damping material.

Moral: it is better to make something out a material that has good intrinsic damping than to try to add damping to something that wishes it were a bell.

[vincitsemper]

Hello,

Cat,I totally agree with you about it being better to start off with a material that is already damped than to try to dampen a bell.but have you ever tried to get someone to make a platter for a 401 that will not ring? If you have any suggestions please let me know as the prices I have seen quoted are more than I have paid for the 401.

I am also surprised about the low efficacy in lead as a damping material.

Regards,

Victor.

[bogle111]

If platter damping is that critical, why don't we see it from manufacturers? Have any of your tts in your extensive collection any (as stock)?

Hi "cats squirrel"
SP-10II's have under platter damping as stock standard - both are identical. They are the only t/t's I have that don't ring like the clappers when putting the platters in place. It is the only platter that I have ever seen that screws in place as well, and I've sold a lot of different t/t's too.

The Oracle doesn't either, but that has a peripheral ring on the platter.

I seem to remember that Chas Traythorn (Metrosound) recommended it on the TD160 Super, but that was a step too far for production, IMM serves me correct.

Regards

[cafe latte]

Hi Guys here is the pic of the lead ring I removed during the restoration. Now it looks very different, painted and shiny, but this just happened to be a pic already posted in the gallery.

And a pic of the rubber ring I fitted round the round the motor shield whatever it is for??

CL

[Ldg]

..... for lead is very poor at damping. The damping factor figure I obtained was 0.032, and whilst it is three times better than copper or brass, it is still a miserable material to use for damping, despite what may have be said in books, magazines and on forums.

No, published loss factor for lead is range 0.05 - 0.3, versus 0.0002 to 0.001 for brass, or 0.0001 - 0.0004 for iron. Lead is orders of magnitude more lossy, and a pretty good damping material, especially so in the right composition.

CL, that rim band looks too small to be primarily for inertia. Trim balancing was a fresh though thought ? Or damping now would seem favourite ! A liitle in the right place, perhaps ?

The rubber motor ring looks pragmatically elegant, CL.

[Eoin]

Slightly off topic. But after the mention of brass..

I've made a subplatter from 1/8 brass sheet. Or just over 4mm. The stock one was diamond shaped very similar to an LP12 shape with three holes for the springs and one for the bearing. The old steel was about 2mm thick or less and very soft indeed. Even though it's edges were turned 90 degrees for stiffness you could probably bend it by hand. It rung like a bell 'duuuunnnngggg' if you gave it a flick.

The brass one is pretty dead by comparison, it's just the flat sheet cut out and finished up and it doesnt want to ring at all much (obviously it'll make some noise if you whack it but it dies down very quickly). I presume it's the thickness here which is making the difference and 1/8" steel would be similar.