Granite base

[Ron Resnick]

Before I decided on using David's special American Sound turntable stand I was planning to use my very heavy current turntable stand. But I did not want to use the MDF VPI top I had from my VPI TNT days.

After researching a lot of materials I came up with a sandwich of 3/4" of lead in the middle with 1/4" stainless steel on top and bottom, both plates of steel “blanchard ground" perfectly flat. The lead would be epoxy coated so no lead dust could escape. The 1 1/4" sandwich would weigh about 180 pounds.

I found one company which would fabricate the entire thing for me at a non-audiophile price (about $1,800), including the blanchard grounding which apparently is fairly expensive by itself and crazy precise (flat to something like .001" over the 27" X 20" surface).

This was my personal, ultimate, quasi-DIY solution for a damped table-top for a rack or shelf.

 

[Barry]

...Nothing special. piece of granite with compression springs underneath with "golden book" cardboard pages protecting the stand. see old photo below. I use 4 springs now as its supposedly better to have the total weight closer to the maximum weight allowance of the springs and does sound better.

Same principle that Townsend now use on their Seismic isolation products.

XV-1 I'm curious what the feet are under the TW Acustic Raven TT. They look different than the BN feet that are currently in use. Thanks.

 

[XV-1]

XV-1 I'm curious what the feet are under the TW Acustic Raven TT. They look different than the BN feet that are currently in use. Thanks.

Hi Barry.

They are the original OEM stillpoint feet Thomas used. I believe they may be aluminium stillpoint ultras. Not sure what he uses these days - obviously different. I did try Stillpoint Ultra SS's under the TW at one point, but preferred the original feet.

 

[andromedaaudio]

Before I decided on using David's special American Sound turntable stand I was planning to use my very heavy current turntable stand. But I did not want to use the MDF VPI top I had from my VPI TNT days.

After researching a lot of materials I came up with a sandwich of 3/4" of lead in the middle with 1/4" stainless steel on top and bottom, both plates of steel “blanchard ground" perfectly flat. The lead would be epoxy coated so no lead dust could escape. The 1 1/4" sandwich would weigh about 180 pounds.

I found one company which would fabricate the entire thing for me at a non-audiophile price (about $1,800), including the blanchard grounding which apparently is fairly expensive by itself and crazy precise (flat to something like .001" over the 27" X 20" surface).

This was my personal, ultimate, quasi-DIY solution for a damped table-top for a rack or shelf.

Sounds good

 

[andromedaaudio]

HPL , in Thickness up to to 25 mm IT has many many Industrial names , above around 25 mm is called. Compact .

Construction, high-pressure laminates consists of laminates "molded and cured at pressures not lower than 1,000 lb per sq in. (70 kg per sq cm) and more commonly in the range of 1,200 to 2,000 lb per sq in. (84 to 140 kg per sq cm).[1]

HPL is made of resin impregnated cellulose layers, which are consolidated under heat and high pressure. The various layers are described below:

Overlay paper, which serves to improve the abrasion, scratch and heat-resistance
Decorative paper, which defines the design and is composed of colored or printed paper
Kraft paper, which is used as core material and control product thickness.
Trade names include Formica, Arborite, Micarta, Consoweld, Alpikord and Duropal.

 

[andromedaaudio]

If you use it you wanna use compact , i use 40 mm to make speakers with , even if i play at ear deafening levels. , And the woofer makes large xcursions there is no vibration not even around the flange of the bassunit

 

[andromedaaudio]

kharma the dutch speakermanufacturer was the first to use it for speakers iirc, and still does among other materials

 

[andromedaaudio]

three layers of paper/resin are placed into a press which simultaneously applies heat (120 °C) and pressure (5 MPa). The pressing operation allows the thermoset resins to flow into the paper, then subsequently cure into a consolidated sheet with a density greater than 1,35 g/cm³. During the press cycle, the decorative surface can also be cured while in contact with a textured surface to create one of many different surface finishes.

HPL consists of more than 60 to 70% paper, with the remaining 30 to 40% a combination of phenol-formaldehyde resin for the core layers and melamine-formaldehyde resin for the surface layer. Both resins belong to a class of thermosetting resins which crosslink during the press cycle creating irreversible chemical bonds that produce a nonreactive, stable material with characteristics different and superior to those of the component parts

 

[andromedaaudio]

foto 3 by andromeda61, on Flickr

 

[jackelsson]

Been quite a fan of granite as a base for audio equipment for quite a while, albeit not on its own. Combining granite with sheets of aluminium does the trick. Both materials used on their own tend to ring and resonate, combined they highly dampen each other resulting in a dead silent base. I use a combination of 3 cm of granite on top of 2 cm of aluminium, combined with an additional air suspension, very effectively under my TW Black Night.

 

[LL21]

Been quite a fan of granite as a base for audio equipment for quite a while, albeit not on its own. Combining granite with sheets of aluminium does the trick. Both materials used on their own tend to ring and resonate, combined they highly dampen each other resulting in a dead silent base. I use a combination of 3 cm of granite on top of 2 cm of aluminium, combined with an additional air suspension, very effectively under my TW Black Night.

Very very interesting...I think that is also what HRS does? They have polymer feet underneath the aluminum frame which has a thick granite insert dropped into the frame.

 

[bazelio]

Granite doesn't strike me as the right DIY base for audio, as it rings like a bell. HRS seems to know what they're doing in terms of damping it in their M3X series, and several TTs were voiced with that base. E.g. some Brinkmann tables, AMG Viella. For DIY, I think the common goto is laminated 3" maple butcher block on top of isolation/damping feet (e.g. Symposium Ultra Padz, HRS Nimbus).

 

[bazelio]

Been quite a fan of granite as a base for audio equipment for quite a while, albeit not on its own. Combining granite with sheets of aluminium does the trick. Both materials used on their own tend to ring and resonate, combined they highly dampen each other resulting in a dead silent base. I use a combination of 3 cm of granite on top of 2 cm of aluminium, combined with an additional air suspension, very effectively under my TW Black Night.

Hi jackelsson, may I ask how you measured resonance to determine this aluminum-under-granite concoction is "dead silent"? Very interested in the results. How many individual sheets of aluminum did you use, and would you mind posting a picture?

Thanks!

 

[jackelsson]

Granite doesn't strike me as the right DIY base for audio, as it rings like a bell. HRS seems to know what they're doing in terms of damping it in their M3X series, and several TTs were voiced with that base. E.g. some Brinkmann tables, AMG Viella. For DIY, I think the common goto is laminated 3" maple butcher block on top of isolation/damping feet (e.g. Symposium Ultra Padz, HRS Nimbus).

Try the combination of granite and alu. As I mentioned before: on their own both materials ring and sing, but combined to a sandwich the result is dead silent.

Then isolate this base, e.g. with steel springs like XV-1 did it, or with air springs, or with Sylomer pads, and you have a highly effective DIY audio base.

 

[jackelsson]

Hi bazelio, seems our last posts crossed. Well, "measurement" was done by a mere knuckle-test, also a highly effective device...
I didn't bother to actually do any real measurements seen how obvious the two materials dampend each other. As I wrote before, it is 3 cm of granite on top of 2 cm of aluminium. Will post a picture later when I get home.

 

[bazelio]

Hi bazelio, seems our last posts crossed. Well, "measurement" was done by a mere knuckle-test, also a highly effective device...
I didn't bother to actually do any real measurements seen how obvious the two materials dampend each other. As I wrote before, it is 3 cm of granite on top of 2 cm of aluminium. Will post a picture later when I get home.

Thank you very much, jackelsson. Curious to see the pics. I saw what you wrote previously and could probably find a single sheet of 2cm aluminum but it could be difficult. So I wasn't sure if you stacked thinner sheets. Intuitively, a single sheet seems preferable. That aside, did you do any comparisons to maple butcher block? Typically we'd use 7.5cm maple as an alternative.

The Townshend Seismic Isolation Pods are excellent and would make great footers.

 

[analogsa]

Try the combination of granite and alu. As I mentioned before: on their own both materials ring and sing, but combined to a sandwich the result is dead silent.

Then isolate this base, e.g. with steel springs like XV-1 did it, or with air springs, or with Sylomer pads, and you have a highly effective DIY audio base.

This actually sounds like a pretty good recipe.

 

[microstrip]

Try the combination of granite and alu. As I mentioned before: on their own both materials ring and sing, but combined to a sandwich the result is dead silent.

Then isolate this base, e.g. with steel springs like XV-1 did it, or with air springs, or with Sylomer pads, and you have a highly effective DIY audio base.

How should we bond the aluminum to the granite? The bond is usually the most critical part in laminated structures.

 

[bazelio]

How should we bond the aluminum to the granite? The bond is usually the most critical part in laminated structures.

In the case of HRS M3X, I do believe the granite rests on the aluminum frame and is not bonded. I don't believe there are any spacers/dampers in between. The footers don't make contact with the granite either. I'm sure we have a HRS M3X owner around who could confirm. I'm not sure if the "inside" of the frame is open and the granite rests on a lip or if it makes contact across the entire face of the granite. If the former, then our situation is a little different with a solid sheet of aluminum and the entire surface area contacting the granite. I'm not sure how I feel about that... But it's a good question!

 

[bazelio]

Here's a (slightly confusing) description of the HRS M3X from a review:

It looks this way: the base is machined from a single billet of aluminum which has milled out recesses for the granite slab on top and the feet in the bottom. The granite sits on polymer pads and its sides do not touch the aluminum base; the only point of contact is the bottom surface. The large aluminum feet are decoupled from the base by the other polymer.

So, if the granite sits on polymer pads, then how does the bottom surface contact the granite?

A picture of the underside below. The frame is clearly not open at the bottom.