Damping TD160 sub platter

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JonnyCJ
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Damping TD160 sub platter

Post by JonnyCJ » 18 Feb 2012 21:18

Greetings all - in the process of modding my TD160 including all the usual bits and bobs.

One area causing me some angst is damping the sub platter with dynamat extreme. I've done the underside of the platter, but not the inner rim, but am concerned that unless it's absolutely perfectly balanced, it will induce some wobble in the bearing/spindle.

Question is, am I ok to use dynamat as long as I get it pretty close and don't damp the outer ring, or would I be better using cork ?

Thanks

Jonny

markcass
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Re: Damping TD160 sub platter

Post by markcass » 19 Feb 2012 11:41

Hi

You could try a ring of thin MDF of the correct diameter, pushed up inside the sub-platter until it is wedged tightly. I have one in my TD160 backup table, supplied by "Joel" via Ebay. He also produces a kit to lubricate the motor and bearing - very useful. He's posted on here as "Violette" and is an ex-Thorens employee.

The damper does seem to work, and is easy to fit (or remove if required). If you have the right tools, you could easily make this yourself.

HTH

Mark

JonnyCJ
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Re: Damping TD160 sub platter

Post by JonnyCJ » 19 Feb 2012 16:40

Thanks Mark- doing lots of platter, deck and tonearm mods, so should hopefully be one of the best sounding and looking td 160's in the country. Will try Joel's mdf mod and fit some cork sheet directly to the underside of the platter. Also fitting an Origin Live DC motor kit as well as some of the SRM upgrades to platter and bearing. Joel's service kit for the bearing is also on the way.

Final mods include a zebrano plinth and mdf baseboard from Rob at Inspire hifi and the SME 3009 s2 improved tonearm with fixed head shell, is away at SME Tonearms in Canada having a full rewire from head shell straight through to phonos, as well as a service.

Any thoughts on applying dynamat to the plinth and baseboard ? Not sure if too much damping is overkill or not.

Cheers

Jonny

cats squirrel
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Re: Damping TD160 sub platter

Post by cats squirrel » 19 Feb 2012 17:43

no amount of added damping is overkill, as many will testify (and many subjectivists will disagree), but you will have to add about ten times the mass of the material to be damped to get anywhere near decent results, I have found (by measurement).

Although adding a small amount of a material to a ringing structure can reduce the resonance amplitude, it will still ring. The only way to make a real difference is to use materials which have good intrinsic damping. This has been used to good effect by one manufacturer of replacement subchassis and arm boards for Linn decks. I'm sure the same effect would be obtained for other suspended decks.

And although many platters will ring if hit, I've failed to detect any signs of ringing whilst playing records on platters which could give the Liberty Bell a run for its money. :D

JonnyCJ
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Re: Damping TD160 sub platter

Post by JonnyCJ » 19 Feb 2012 17:51

Interesting - can't really remember my o level physics that well, so get a bit lost on amplitudes and sine waves, but grab the gist of what you're saying. I take it you're referring to carbon fibre sub chassis ? Would applying dynamat to an aluminium arm board adapter help any ? I know there's two schools of thought regarding using grommets for tonearm mount, to arm board or not (I'm going for the none option), but is any damping advisable around this area ?

Thanks

Jonny

cats squirrel
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Re: Damping TD160 sub platter

Post by cats squirrel » 19 Feb 2012 18:18

JonnyCJ wrote:Interesting - can't really remember my o level physics that well, so get a bit lost on amplitudes and sine waves, but grab the gist of what you're saying. I take it you're referring to carbon fibre sub chassis ? Would applying dynamat to an aluminium arm board adapter help any ? I know there's two schools of thought regarding using grommets for tonearm mount, to arm board or not (I'm going for the none option), but is any damping advisable around this area ?

Thanks

Jonny
hi Jonny,
no, not carbon fibre, which, on its own, is a useless material for damping duty, I found, although as a facing in composites, it might be fine. The material I was alluding to is a sandwich of aluminium facings with an mdf core.

I think dynamat is OK if applied to metal panels, like in automobiles, but not too effective for turntables to the degree you are asking about. Try a plasticine type material, like 'Newplast'.

Grommets, I think, were first used by SME, when plinths and arm boards were more like sounding boards on guitars than the inert structures they are today on the best examples of turntable design. So if you can guarantee a vibration free arm board, then bolting the arm base to this is the way to go, IMHO. So any extra damping around this area is a good thing. I have found half the vibrations affecting a stylus placed on a stationary record comes through the arm base/arm route, and half from the platter, if the turntable plinth is vibrated. Using grommets will introduce the possibilty of movement between the arm and platter, which must be kept perfectly aligned at all times. :)
HTH
Last edited by cats squirrel on 19 Feb 2012 19:02, edited 1 time in total.

JonnyCJ
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Re: Damping TD160 sub platter

Post by JonnyCJ » 19 Feb 2012 18:31

Thanks Cats - all very valuable info !

JonnyCJ
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Re: Damping TD160 sub platter

Post by JonnyCJ » 27 Mar 2019 21:04

Back again !

Been out of the loop for a “few” years whilst a small boy was brought into the world and grew up. Ended up selling the 160 and had a mint Garrard 301 sitting on the plinth for a few years with very little use, but it looked pretty....

That’s now being sold and I’m going back to a 160 for less worry about small fingers and more vinyl time.

Today’s question revolves around the age old topic of damping. When my new to me 160 arrives I was thinking of doing all the usual mods, but replacing the bottom board and arm board with 10mm slate. I have a local source who can cut to size. Overkill or worth doing ?

Cheers

Jonny

nezbleu
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Re: Damping TD160 sub platter

Post by nezbleu » 28 Mar 2019 18:19

I think an improved bottom board can add a lot of structural rigidity to the plinth, which is otherwise pretty flimsy. If you can make the slate bottom a snug fit and tightly coupled to the plinth it could help a lot. It the plinth is just kind of sitting on the slate then I think you would be better off with plywood or MDF cut to size and fixed with multiple screws.

On my 160 I cut "battens" of 1/2" MDF and glued them on the inside of the plinth (there are a few areas where you need to be careful), this both stiffened and damped the plinth considerably, and gave me something to screw the new MDF bottom to.

Pics when you are done, please! :)

JonnyCJ
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Re: Damping TD160 sub platter

Post by JonnyCJ » 30 Mar 2019 07:24

Hmmm - bit of an update.

The deck arrived, however, the RB250 was attached to the arm board when it left the seller and upon arrival it wasn’t. Not sure what happened as it was securely packaged, but it’s taken a hit somewhere along the line.

It’s currentky on the way back to the seller and I start looking afresh.

Pants !

oztayls
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Re: Damping TD160 sub platter

Post by oztayls » 06 Jun 2019 11:30

The platter should not be dampedas it has been balanced at the factory. A ring of 80gsm paper between the inner and outer platter seems to eliminate any platter ring you you have. If you’re not experiencing any “platter ring”, do nothing.

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