Granite and Marble for isolation?

doucanoe

Registered Audio Abuser
In a never ending search for ways to improve or change the sound of my setup, I decided to experiment with Granite and Marble for component isolation. Being in the construction remodel business, I have excess to sink and fixture cutouts in these materials. My supplier for Granite and Marble countertops has stacks of these sitting around and available to the public for a reasonable fee. Different sizes with polished tops and usually 1 1/4" or more in thickness.

Originally I thought that these would be great for isolation and vibration damping because of their sheer mass. After doing some research, It seems this might not be the best way to achieve component isolation because the Granite and Marble has a tendancy to "ring" in spite of the weight. Also, the use of G/M might elevate (brighten) the mids and highs which can be a good or bad thing dependent on your current set-up.

Someone had commented about the fact that I was using a Townsend Siesmic Sink under my TT. This is an air bladder platform and the thought was that it might not be recommended for use under a TT. I haven't checked to see what the manufacture has to say and confirm this yet.

I found a pair of Electro Voice SP15b's a while ago and dropped them in a pair of Altec cabs the had a 15" cutout already in the baffle. The cab's are really too small for the drivers so Im running them with the backs removed (ala open baffle). They sounded o.k. but the bass was less than I expected for a 15" woofer and the mids and highs were not as clear and defined as my SP12b's in similar sized cab's. Elevating them @1'-0" off the ground helped quite a bit but still not as defined as the SP12b's in any areas.

All of this got me to thinking, My problem is that everything sounds "there" but is a tad muddy. I had a piece of marble 1 1/4" thickness that would be just the right size for under my TT. So out came the air bladder platform and in went the marble. The Marble slab is supported by (3) brass cones and the TT sits on top of the works. The sound in the mids and highs has become more defined and tilted upward. Brighter, yes, but not in a bad way at this point. I will have to listen for some time to see if its annoying in the long run.

Maybe just removing the air bladder platform would yield the same results but Im not sure yet -or- using something that might be undesireable in most system is working for mine :scratch2:

Anyone have any of there own experiences or thoughts regarding the use of Granite or Marble isolation?

RC
 
I have a 3" thick slab of granite that I used with my TT. Your conclusions about its effectiveness are on the mark. Even with all that mass, with a suspended table my kids could create footfalls from a fairly long distance away. It sort of defeated the purpose to keep using it so IIRC it's hidden under one of my sofas.

Mike
 
I have a ~1" thick chunk of granite under my turn table that I scrounged from a Habitat for Humanity Re-Store. I didn't notice any difference one way or the other, but my table has a servo-arm (Sony PS-X500 Biotracer) that already does an excellent job taking care of vibration issues at the lower frequencies. I did put another piece of scrap under my little 6BQ5 tube amp (Fisher SA-16) and it seemed to help a very faint case of microphonics that could be heard when stomping around.

Conclusion? No effect with turntable (a shelf might be a better option), but a positive effect with a tube amp. It does look good, though.

- JP
 
Concrete, marble, granite all resonate in free air. Try loose sand in a cloth bag or just nice white sandbox sand loose in a tray. You want something that will damp movement and convert it to heat, which means particles that move and rub against one another. Anything solid will tend to either resonate at one or more frequencies or simply transmit solidborne vibes. Lead shot might work too, but would be a little harder to find and work with.
 
Granite/Marble does a fine job to isolate under amps and speakers.I don't know the real reason why,perhaps the mass absorbs at a different frequency.Under TT the best is an absorbant material,I use 3" mdf and it deadens everything,my kids run around the room (really spongy floor) and no movement.The TT is a sprung Thorens.

Regards
Mike
 
Well, kids, if you're having a problem with solidborne feedback, try it both ways and report back here.
 
Directly attach the mass to your TT with metal points or what ever you like just not some antivibration thing you want to add the Mass to your table. Then put the Mass on super balls a Hemeroid donut, tennis balls or something like that. That way the vibrations coming from the floor have to pass through the superballs etc. in order to excit the Mass and trying to get say 50Lbs of mass to start vibrating is hard.

I don't have it finished yet but my TT a Pro-Ject 1.2 will be point mounted to a 48lb 15" x 19" slab of 2" think concrete that will be puttied smooth with bondo and painted to look like some fancy rock. This will then rest on 12) 1" diameter super balls grouped 3 to a corner. this then rests on a cabinet made from 1.25" thick MDF that rests on 4 inline skate wheels. the cabinet has about 90 albums in the bottom a preamp and CD changer and Will have a RCM as well about 300 lbs all told. try bouncing that up and down LOL


So for my set up from the floor

Wood floor

absorbant wheels

MDF wood Mass with about 100+lbs of non attached mass contained in it.

Super balls

50lbs of concrete.

short metal points or threaded inserts (haven't decided yet)

TT
 
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OK, to start with, I've no idea what the physics of this is, so don't ask me. That said, here's an idea:

My main speakers are built out of Corian. I'm told that Corian has different physical properties than any real stone and doesn't ring as much. I can tell you they weigh 250+ each, and are a bitch to move. Corain comes in various thicknesses, and is supposed to be easier to work with than real stone.

Anyone tried it or have any real knowledge?
 
Negotiableterms said:
OK, to start with, I've no idea what the physics of this is, so don't ask me. That said, here's an idea:

My main speakers are built out of Corian. I'm told that Corian has different physical properties than any real stone and doesn't ring as much. I can tell you they weigh 250+ each, and are a bitch to move. Corain comes in various thicknesses, and is supposed to be easier to work with than real stone.

Anyone tried it or have any real knowledge?


I do know this about Corian and other similar materials. Its usually available (countertop material) at 1/2" thickness and it is very easy to work compared to stone. I have heard the same things about Corian being a much better vibration dampener.

Here's an Idea.... 1- slab Marble or Granite @1 1/4"- 2" thickness and 1- piece Corian @ 1/2" cut to the same dimensions. Sandwich in-between another material like say a Sorbathane (sp?) mat. You would have dissimilar materials that would resonate differently with a "dead" material between them. Also, you would get the high mass from the stone.


Mark W, wouldn't a simple cone decoupling of the mass from the cabinet/rack accomplish the same thing. I thought that was what the point on the cone was supposed to do. Seeing as how vibration travels both ways, how do you orient the cone. Point up or point down? I guess it would depend on which vibrations you are most concerned about. I was going to support the table with cones also but I dont currently have anything tall enough.


wualta, I do have a Bright Star Audio sandbox that is in semi retirement. I will have to work that into the program again and see what happens :thmbsp: . It is very effective but big. I used it with a seperate amp stand but my room is smaller now so into retirement it went.

I have to admit JP, It looks pretty cool. I will have to decide how effective it is in the long run.

Good discussion guys,

RC
 
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I myself have thought about the Granite/Marble procedure for the TT. But, I have also thought about experimenting with the SandBox method that Wualta made refernce to. For those that are interested I found this in my archives about sandbox projects.
Later!
 
Negotiableterms said:
My main speakers are built out of Corian. I'm told that Corian has different physical properties than any real stone and doesn't ring as much. I can tell you they weigh 250+ each, and are a bitch to move. Corain comes in various thicknesses, and is supposed to be easier to work with than real stone.

Man, I'd like to see a pic of that.


I never got into the whole isolation thing, seems to be alot fo debate regarding the effects and benefits.

I did use a granite slab for my sub in the home theater, since it was spiked and heavy, I wanted something strong so it wouldnt get all scratched up

I have since stopped using it since my DIY sub is now on casters
 
Maple platforms

Maple seems to make a great platform, too. Here's a link to a guy who'll custom make them for you. I had him make 2 for me and they've worked out really well. Chris Futrick at www.timbernation.com

Mapleshade thinks pretty highly of maple, too:
http://www.mapleshaderecords.com/audioproducts/maple_main.php

I don't really know why, but the stuff seems to have a good balance of mass and damping. I know that replacing the lightweight shelves on my Sound Org stand with an LP-12 is taboo, but it sounds better now. Better enough that since I snapped this photo I "had" to spring for an Ekos arm.....

Dave
 

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Geeze NT, You have a pair of the Pipedreams! I have never had the pleasure of hearing those but from what I have read the are the real deal.

RC
 
Use cones

Think about the physics of transference; if a mass isn't connect to another vibrating mass then there is no transference. If they are tightly coupled then there is maximum transference.

If they are connected, even through a 3 " slab of granite, the vibrations are going to be conducted through to the TT via the contact patch (those rubber feet).

If the contact patch is a point, then there is the minimum possible transference.

Try it. Cones work.

Paul
 
Makes sense to me Paul, Im going to revove the cones and drop the marble to the top shelf and try my brass cones under the TT.

Thanks

RC
 
Charivari said:
A lot of the pictures on that page aren't working. Does the entire system look a bit like this?

Nearfield Acoustics went effectively out of business then was reborn with different systems.

JP, the ones in your pic are the previous generation, in which the towers are squared off. Mine are the next gen, which are hemispherical in shape, and made of Corian. The Depth Charges (subs) are similar, although my 18s only have two instead of the four that come with the 21s. Since each contains 2 18" drivers, I don't actually experience a lack of bass!

That said, I have this dream of switching them out with a pair of Velodyne 1812s, because they're better in the upper range, around 150 Hz, which is where the Pipedreams are weakest. Audio... nothing is ever perfect.
 
Last fall I had the opportunity to tour Corning Tropel's factory in Fairport, NY. Tropel is a world leader in the manufacturing of microlithography objectives and interferometry measuring devices. As such, their products are manufactured to extremely high tolerances much greater than necessary for even ultra high end audio. They used huge (I mean HUGE) granite slabs to ensure vibrations were kept at a minimum during the manufacturing and measuring processes. I'm sure there are other far more absorbent materials out there, but as a weight bearing material needing to remove extremely small vibrations, it proved the best option for the company with cost being no objective. The caveat to their approach was that it required the granite being directly mounted to the buildings massive concrete foundations so that there would already be very miniscule vibrations, something I think few audio enthusiasts are willing to do, astetically or financially.
 
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