The Effect of Damping on Sound: Racks and Turntable Plinths

Apr 10, 2018
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#1
PeterA and I started this thread to ask some general questions about damping and how it specifically affects rack systems and turntable plinths, after seeing the incredibly beautiful pictures of Ovenmitt and me on the lookout to get better SQ from my Garrard 401.
Peter has been fine tuning the sound of his rack while I have been experimenting with different wooden plinths for my DIY Garrard turntable project.
Here are some questions that came up in our discussions:

1. Is it possible to over-damp something in this context?
2. How do we know, what do we listen for?
3. How do material properties affect the actual audio signal? Is it all about controlling resonances?
4. How do we strike the right balance? Trial and error until it sounds right to us?
5. It this really about tuning the system by finding the right balance between too much and too little damping?
6. Are there any general principles that we should know about?
7. Does a Garrard realy need another plinth as a Lenco or a TD124? Or do they all react the same to differnt materials? (Idler wise)

Below are some plinths that I designed and my impressions of how they sound. I will post my findings on my project and how it evolves and hope to get some information here.

Peter has described his recent experiments with his audio rack and his resulting listening impressions in this link to his system thread, posts #1038 and #1041.

https://www.whatsbestforum.com/threads/sublime-sound.12853/page-53

I am working on my 401 myself, I'd like to know how to get better SQ with the Garrard.
I had a 6 layer birch multiply plinth and was quite happy with it, till I noticed that it is really muddled and not very open in the middle.
2020-02-27 22.36.23-2.jpg

After some help from another forum, I was told to try the "Vinylista" style plinth.
This is what I have made with pieces I had around :
2020-03-15 17.36.29.jpg

This is really something! Here there is a better defined bass, the mids have the same grip as the bass and it is extremely dynamic and lively.
But, still, the mids are not really open. Reverbs are not really there, 3d is quite flat.
In Classical music there is almost no room information. When listening Eva Cassidy, when I listen via digital, a lot more 3d and separation.
(Roon - hqplayer - ifi Purifier - idsd micro, so not really high end)

What's your experience? Can I get there or should I really think about another turntable?

My system : 401 — Helius Aurora - AT OC 9mkIII - Paradise Phono

Regards, Remco
 
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PeterA

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#2
Remdeck, Ovenmitt's thread is an interesting thread with lovely photos of DIY turntable projects. Thank you for starting this thread and sharing your experience with your tables. I love your willingness to experiment and build your own stuff. I don't know if this will be useful to you, but I can share my experience with some things I have recently learned about birch plywood as you rack shelving looks a bit like mine.

I built a birch plywood rack and amp stands to match the birch plywood enclosures of my old Magico Mini IIs. I really like the look of the rack. It is extremely solid and very heavy. I thought I was all set for equipment support, but then fellow member DDK suggested that the plywood might be overdamping my sound. He suggested I remove a thick plywood base shelf which sat on the floor into which the rack was spiked. I used this to protect the 200 year old floor boards in my listening room. He then suggested placing thick stainless steel plates on each shelf under each component. This mass loaded the rack and I immediately noticed an opening up of the sound, at all frequencies. Now this corresponded with other changes to room treatment and speaker placement, but I did isolate the effect of the steel plates on the sound, and it was all positive.

I would summarize it as more information retrieval presented in a more natural way. Everything now sound more open, better balanced, increased clarity, and more alive. Perhaps my lovely birch plywood shelves were in fact sucking some of the life out of the music. I have since been experimenting with spacers between the steel plates and the plywood shelves. First, natural wool felt, now large thick rubber O rings. The steel plates ring more with the O rings, but the sound is better and more natural. I think the components benefit from the mass loading of the rack but also from the separation from the plywood.

Here is a suggestion from afar which may or may not be helpful to you: perhaps your plywood plinths are overdamping the sound from your turntable and arm board. Just a thought, and I may be completely wrong, but I found this to be the case in my system, and it was well worth the effort to install these heavy steel plates. I also wonder if something similar might be happening with your turntable plinths. Perhaps some solid hardwood might sound better in place of the birch plywood of your first photo, or even a thick steel plate used as a plinth in your second photo. I am finding these materials can really affect the sound.

IMG_0060.jpg



My system link on WBF: https://whatsbestforum.com/threads/sublime-sound.12853/
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Apr 10, 2018
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After the one layer ply above I put a chipboard underneath it to try what this:
2020-03-22 14.35.38a.jpg

This improved the sound in all matters. The bass was more defined and the mids even better than before. Room information got better but lots of work still..
 
Apr 10, 2018
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PeterA, this is quite some information which can really be helpfull!
As I have been thinking about the overdamping you are talking about, never thought it would have this an impact on the turntable.
Actually as my wife was with me on her first Hifishow, Matthias Böde from the German Stereo Magazine demonstrrated a cd player on one rack. After that, he just placed it on another rack (same manufacturer, another model) it sounded much better. My wife didn't understand what he had done, as she was looking around at that moment of repositioning. She heard the difference and could even tell what the difference was, even as she didn' know what was changed.. real funny :cool:

After your post and some more reading, I have some new conclusions.
The topplate should be of the most rigid material, with the right damping (not to much)and not to heavy . This is why most manufacturers of plinths come up some material like Panzerholz (synthetic resin densified wood), corian (mineral based material), or slate.
On slate, this can be very difficult to get right and have to try to much sorts of slate.
Corian is no problem for kitchen-building companies. The problem with Panzerholz or the like can be how to get this material in such small quantities. I'll look around.
Also possible is a choppingboard from Ikea, which is made of bamboo, which is extremely rigid as board. It costs close to nothing.
Has anybody tried and have some experience with this ?

Because I remembered the use of different materials for the tonearm-pod, which should make great SQ differences. I wanted to try this also, as I had some hardwood around to exchange with the multiply armboard I had till now.
I mounted a oakwood (?) board:
2020-03-26 10.03.40.jpg
The difference in SQ to the ply is quite big this time again. Bass is much less, the quantity is the same now as the digital system. The dynamics and the grip are still there. Rooms, delays, 3d and depth have increased significantly.
It really looks like the theory of the overdamping could be right! And that ply can/will overdamp the sound...

The decoupling with sorbothane can be a good thing and I found these which are even not really expensive and should be very stable over time.
SMD Sorbothane domes
Is there anyone with experience with these?
Support pillars

Regards Remco
 
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PeterA

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Dec 7, 2011
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#5
remdeck said:
PeterA, this is quite some information which can really be helpfull!
As I have been thinking about the overdamping you are talking about, never thought it would have this an impact on the turntable...


After your post and some more reading, I have some new conclusions.
The topplate should be of the most rigid material, with the right damping (not to much)and not to heavy .

Because I remembered the use of different materials for the tonearm-pod, which should make great SQ differences. I wanted to try this also, as I had some hardwood around to exchange with the multiply armboard I had till now.
I mounted a oakwood (?) board:


The difference in SQ to the ply is quite big this time again. Bass is much less, the quantity is the same now as the digital system. The dynamics and the grip are still there. Rooms, delays, 3d and depth have increased significantly.
It really looks like the theory of the overdamping could be right! And that ply can/will overdamp the sound...
Thanks remdeck. To what do you refer when you write "topplate" in the above sentence?

I also agree with your conclusions that something can be overdamped, depending on the context. I do think you should start a new thread so as to not dilute ovenmitt's wonderful OP. I would find a discussion about damping and its effects to be very interesting. I want to learn more about the subject.
 
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Apr 10, 2018
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To what do you refer when you write "topplate" in the above sentence?
Maybe topplate is no word in your vocabulary :)

I mean the upper board for the Garrard motor and arm.

I think this is of most importance to get it right here....then adressing the rack on which the turntable is positioned. Working with metal sheets, rubber sheets or otherwise, to get the live back in the system.

Regards, Remco
 

bonzo75

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#8
I'm also contemplating a Garrard build. I'm interested in any comments on slate, here is an interesting plinth design on ebay:

View attachment 63194
I have never heard a wooden plinth Garrard sound good, heard many of them. Always low resolution and plinth colored. The best I heard was @christensenleif@msn.com, whose system is close to Mike's without the room, though he does have a big room to let his bass go linearly to 15 Hz, all horn loaded

It was Stefan bertoncello's bearing and bronze platter, CNCed chassis by a classic hifi of UK, plinth by peak hifi of UK, and put together by Jap Pees from Hanze hifi of Holland, whose 401 I have heard as well.

The bearing itself I understand is from the Shindo, but Shindo 301 on its own was disappointing compared to the Schopper 124.
 
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Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
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#9
my Dobbins 301 plinth used a constrained layer approach. it's been so many years i don't recall the exact sequence of the layers, but it included at least one layer of metal. it was a matter of the plinth being stiff, but lively. not over-damped.

and it was voiced with Stillpoint footers. i recall trying other footers but it needed the slight hardness of those Stillpoints for the correct tonal balance.

that Garrard really boggied!
 
Mar 18, 2017
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#11
Lately I have been experimenting with surfaces ranging from granite to delrin to carbon fiber, employing a a constrained layer damping approach, with Sorbothane washers or isodamp. I have had very positive results with two 1/2" thick delrin plates, then using isodamp as the CLD. My ARC Ref 2SE Phono rests on this.

I've also had positive results using carbon fiber sandwich boards, either foam or flax being the sandwich material. That in turn resting on another surface with isodamp as the CLD.

My rack is from Adona, and I plan on obtaining more isodamp to use inside the aluminum struts.

Hope this helps,

Bruce
 

jackelsson

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Dec 1, 2013
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#12
He then suggested placing thick stainless steel plates on each shelf under each component. This mass loaded the rack and I immediately noticed an opening up of the sound, at all frequencies. Now this corresponded with other changes to room treatment and speaker placement, but I did isolate the effect of the steel plates on the sound, and it was all positive. I would summarize it as more information retrieval presented in a more natural way. Everything now sound more open, better balanced, increased clarity, and more alive. Perhaps my lovely birch plywood shelves were in fact sucking some of the life out of the music. (...)
Peter, this is most interesting. What thickness do these steel plates have? And what ist the specific reason to choose stainless steel over e.g. aluminium?
 
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PeterA

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#13
Peter, this is most interesting. What thickness do these steel plates have? And what ist the specific reason to choose stainless steel over e.g. aluminium?
I can not answer why he recommended stainless steel over aluminum, but I suppose steel is heavier and the purpose was to mass load the shelves. These are 14" X 18" X 1" and weigh about 75-80 lbs each. To save money, I specified a mill finish rather than a machine finish. Edges were rough, so I sanded them down myself. I would have preferred a nice machine finish with a reveal around the four top edges, but that would have cost about $1,100 per plate. I paid about $230 per plate with mill finish. They are # 304 stainless steel. A36 steel would have been even cheaper.

The plate under my turntable is regular steel, 20" X 30" X 3/4" and weighs 135lbs. That was recommended by Vibraplane to preload the unit for optimal performance. The pneumatic isolation has been removed, but I retained the steel plate. I am extremely pleased with the results.
 

analogsa

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Apr 15, 2017
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#14
What's your experience?


My experience mirrors yours. About 20 years ago i built a very similar multi layer baltic birch plinth for a 301 and was shocked at how bad it sounded. In stark contrast to the many who were building similar plinths at the time. Plywood has its own strong sound character and the more layers you add, the stronger it gets. Really bad as a shelf material too. What did help a lot was drilling it through and filling the voids with lead shot.

It is unreasonable to expect a large chunk of homogeneous material to sound any good. IME this is also true of all types of stone, which if anything, add an even more obtrusive colouration than plywood.

Layering different materials or going for a CL design is very different. Adding some elastic compliance is also a good idea for an unsuspended turntable. I believe you are on the right track.
 
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Kcin

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Mar 27, 2016
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#15
I can not answer why he recommended stainless steel over aluminum, but I suppose steel is heavier and the purpose was to mass load the shelves. These are 14" X 18" X 1" and weigh about 75-80 lbs each. To save money, I specified a mill finish rather than a machine finish. Edges were rough, so I sanded them down myself. I would have preferred a nice machine finish with a reveal around the four top edges, but that would have cost about $1,100 per plate. I paid about $230 per plate with mill finish. They are # 304 stainless steel. A36 steel would have been even cheaper.

The plate under my turntable is regular steel, 20" X 30" X 3/4" and weighs 135lbs. That was recommended by Vibraplane to preload the unit for optimal performance. The pneumatic isolation has been removed, but I retained the steel plate. I am extremely pleased with the results.
I had a similar experience with a very heavy mass loaded shelf below the turntable with very good results.

I had friend gift me the stand and top plate of a Goldmund Reference turntable. The stand is nothing special- I had it raised with some hollow structural steel to a better level for a my conventional Brinkmann.

The top plate however is something unique almost 3" thick brass that has been anodized black. It is over 150lbs . It still has the machining in it for the Golmund but the Brinkmann fits nicely on this. Where you you would find a piece like this today I don't know? -- perhaps for use in a ship or sailboat keel. It would be hideously expensive. It made a fundamental difference in quietness, energy and solidity .

I really don't know what happened to the rest of the Goldmund Reference... apparently it was a problem piece and the owner parted it out and moved on- nice to have such problems. Wish I had known before it went to pieces. I still have the controller.

IMO you can't beat mass - I am fortunate to sit on a concrete floor which makes a difference as well. I've added the top HRS platform as well whatever the model # is for a further improvement in my experience.

goldmund reference.jpg IMG_1785saved.jpg
 
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213Cobra

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Aug 27, 2018
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#16
I wandered my way through a variety of Garrard plinth builds before landing on an extended solution. I ignored slate, as no slate plinthed turntable ever sounded musically convincing to me. I understand why some people like the resulting voicing but it's a tonal and dynamic coloration, in my experience. So I started with a laminated mass-loading plinth. I did maple ply laminate; birch ply laminate, each capped with ebony or cherry, top and bottom. I also tried an mdf laminated plinth for a short time. Then after reading about the Loricraft recommendation against mass loading, I prototyped a birch-ply Loricraft-style (two slabs separated by corner risers) and found that to unleash the 401's dynamics and made the voicing distinctly more neutral. The sound became immediate, bursty, agile instead of heavy-handed and dark with dreadnought foreboding. So I went one step further:

G401-lori.JPG

Loricraft style combined with the Shindo glued blocks construction. Shindo does it with cherry, IIRC, in the mass-loaded form. This uses teak blocks for top and bottom with teak risers. I was contemplating trying this but then found a guy in Thailand already making it. So it was a simple eBay buy. After experimenting with a wide range of feet options, I settled on 1 pound adjustable brass cones on the three footer points, and attached them to the flat bottom of the footer-posts with double-sided-adhesive Grungebuster Dots from Herbie's Audio Lab. I had found them effective for replacing the sprung feet on my Luxman PD-444 turntables with similar 1 pound brass cones.

The 401 is far livelier than on any other plinth type I tried or heard a 401 mounted elsewhere. It is not as quiet as a mass-loaded table. At high volumes more motor noise creeps in than with the mass-loaded plinths, but this is only really distracting at high-SPL, and I've been finding incremental ways to tame that aspect. Musically, the Garrard in this plinth exhibits locomotive drive, neutral tonality, fast, bursty, explosive dynamics. These tables take some tweaking compared to modern drive systems. Tonearm is Thomas Schick 12". Cartridge is Ortofon Meister Silver G.

I heavily experimented with resonance control via racks, footers, tweaks for other components, but that's for another post.

Phil
 
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Mar 28, 2013
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It's and interesting subject

I agree, what you place equipment on often makes a difference. Over damped, place a cdp on Sorbothane or some other form of rubber..! That sounds like it could be psychosomatic :)

I also built my rack, following the Burmester principle - make it solid (though not nearly so solid as the OPs). 30mm birch ply bonded to 30mm block board. I'm unskilled but having researched some I figured grain running horizontal below and vertically above would be sensible.

I've tried a lot of footers/spikes/cones over the years, from the mad expensive Dalby Audio through Stillpoint, Nordost, Clearlight you name it. Most impart a character to equipment, subtle usually but occasionally very noticeable. The Dalby introduced a remarkable level of resolution to mids and upper freq in my system when placed under an EMM Labs cdp. They also robbed deep bass of it's weight and power. Quiet remarkable. I'm quiet sure that under another piece of equipment they may have worked well.

I did find cones that work for me. To these ears they offer positive without negative. Alto Extremo from Germany. They're quiet unremarkable, solid machined alloy or Delrin bases, a bearing of various materials supporting either a brass, alloy or Delrin support, there is one sitting on top of the TT in the pic I've added. I've yet to find a component I didn't like better on them.

I also use Quartzstone under some components.

Everything I've added has been done on a do I notice a difference, do I not. Do I prefer it, do I not basis. I'm happy with the outcome. Well worth experimenting. One thing is for sure though, everyone listens differently and we often have very different priorities.

20200322_164418.jpg
 
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Nov 4, 2019
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#18
I've also had positive results using carbon fiber sandwich boards, either foam or flax being the sandwich material. That in turn resting on another surface with isodamp as the CLD.

My rack is from Adona, and I plan on obtaining more isodamp to use inside the aluminum struts.
Hi Bruce. Sorry for jumping in late, but are you saying that you are experimenting with shelves that are different from the ones provided by Adona? I thought Adona already used a CLD like multilayer shelf solution?
 

spiritofmusic

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Jun 13, 2013
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#19
I'm also contemplating a Garrard build. I'm interested in any comments on slate, here is an interesting plinth design on ebay:

View attachment 63194
Jeffrey, I can only highly recommend slate as a good way to go. My Trans Fi Audio Salvation rim drive sports a 22kg slate plinth, and an integral part of the extra performance I'm squeezing from it is the 93kg slate Stacore isolation platform on 50kg inert slate stand that the tt sits on to be supported on the floor.

You could say I'm a fan of slate to spin lps w 160kg of the stuff under my vinyl.
 
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