Damping material between turntable plinth & base?

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Ken J.

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Damping material between turntable plinth & base?
« on: 28 Sep 2010, 08:21 am »
Hello,

This is my first post to this forum. I joined just to ask this question, the answer to which I think might benefit others (certainly others with the same turntable as I have, but perhaps others building DIY turntables with separate plinths and bases).

I have a vintage Goldmund Studietto turntable, which is basically a high-quality direct drive motor, platter, electronics, and tonearm mounted to a slab of acrylic-like material (methacrylate) separated from the base--another slab of methacrylate--by three very wiggly and jiggly compressed coil springs that resonate at audible frequencies.



The stock springs are almost universally acknowledged to be the weak point in the design of this turntable, and most owners report dramatic improvements in sound quality from replacing the springs with Sorbothane pucks or something similar. In the past, I have tried several different materials (including various combinations of layers of EAR C-1002 Isodamp, closed-cell polyurethane foam, and some very sticky stuff I bought many years ago from Micheal Percy called Microsorb), and indeed, they all were a significant improvement over the stock springs. I currently have three gray Pandafeet (http://www.positive-feedback.com/Issue13/pandafeet.htm) between plinth and base, and although I think they do a very good job of keeping resonances in the shelf and base from entering the plinth, I'm not convinced they're that good at neutralizing resonances in the plinth itself.

Thus, I am considering other damping/decoupling materials, including those from HAL. In particular, I was thinking about trying either the extra thick (1/8") 1-5/16" diameter Grungebuster Dots or the 9/32" thick 1-5/16" diameter Giant Fat Dots. The 1-5/16" diameter is ideal for this application because that's pretty close to the diameter of the height-adjustable Delrin spring holders between the plinth and base on this turntable.

So, any recommendations as to which material would be preferable and whether stacked dots would be a good idea in order to increase the thickness of the damping material?

I know these HAL products aren't supposed to be all that weight sensitive, but for what it's worth, the weight on each of the three Delrin spring supports is not evenly distributed. The one of the right side of the plinth about half way between the front and rear carries the least weight; the one on the left side near the front carries a bit more; and the one on the left side near the rear carries the most. I've never weighed the plinth with everything on it, but I estimate that it might weigh about 20-25 pounds.

Best regards,
Ken J.

Herbie

Re: Damping material between turntable plinth & base?
« Reply #1 on: 28 Sep 2010, 01:05 pm »
Hi, Ken. We have lots of customers using Tenderfeet or Big Tall Tenderfeet to replace plinth support springs in Thorens, AR, and other suspended turntables. Tenderfeet also achieve significant sonic improvement replacing aftermarket Sorbothane springs and pucks.

If you want a lower and/or wider profile, Extra-Thick grungebuster Dots are ideal; they can be stacked to achieve more height.

Steve
Herbie's Audio Lab
« Last Edit: 28 Sep 2010, 05:41 pm by Herbie »

Ken J.

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Re: Damping material between turntable plinth & base?
« Reply #2 on: 28 Sep 2010, 04:58 pm »
Hi Steve,

Thanks for your reply. I hadn't considered the Tenderfeet, but I'll have to give them a look.

Would you not recommend the Giant Fat Dots in this application at all, then?

Thanks again.

Ken J.

Herbie

Re: Damping material between turntable plinth & base?
« Reply #3 on: 28 Sep 2010, 05:30 pm »
Because every system has different vibrational factors, you can't always predict with certainty. Fat Dots are usually better suited for loudspeaker support and other applications requiring a firmer, less compliant interface. Fat Dots can be used together with grungebuster Dots or Tenderfeet though, for a hybrid approach.

Steve
Herbie's Audio Lab

Ken J.

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Re: Damping material between turntable plinth & base?
« Reply #4 on: 28 Sep 2010, 07:50 pm »
That's good to know. I'll probably get a few Grungebuster Dots and Fat Dots and play around with different combinations to see what sounds best.

Thanks,
Ken