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I've seen lots of discussion about Gatorboard (a/k/a Gatorfoam) in the archives going back about ten years or so, but not much recently. Recall that it comprises the inner layer of Symposium shelves and is in the recipe for a popular DIY aluminum/MDF/foam isolation platform.
I'm trying to find a suitable material to support a 2" solid maple isolation platform on top of a 2" solid maple rack shelf. (I wouldn't use the isolation platform at all if it weren't for the need to expand the surface area of the rack shelf in order to accommodate my turntable. So, I'm not looking for much in terms of functionality or tuning or the like.)
Would a large piece of Gatorboard "sandwiched" in between be a reasonable way to separate the two maple boards? (They must be separated in order for the upper board to clear the "caps" that extend through the top shelf of my rack.)
It strikes me that this configuration, if the Gatorboard is almost as large as the maple boards themselves, may be similar to the DIY Symposium shelf -- minus the aluminum layers.
Thoughts on this, or suggestions on other ways to support the isolation platform?
Jim, one other option is to use some tall brass cones between the two maple boards. The ones shown have threaded stubs on the top -- I just drilled appropriate sized holes in the bottom of the Nott' platform and screwed them in. In your case, if the top of the cone was screwed into your top platform, the weight of the board and 'table pushing on the points at the bottom would probably sink them enough to give you some nice lateral stability (I have two cats, and know well the need). :) Or you could invert the cones with the points up and thread them into your bottom shelf. Either way it would be pretty darn stable. Just a thought...
Have you tried the 40mm x 10mm Carbon Fiber Disc under the tip of the tall brass cones? In order to rigidly support a 1" thick HQ laminated bamboo platform for my CD transport, I use the carbon fiber disc under the tips of Audio Points 1.5AP1D brass cones, with a Herbie's Audio Lab Thin grungebuster Dot (black version, with optional adhesive backing) adhered under each disc, placed on a rigid MDF rack shelf surface. The carbon fiber disc with an indentation located on one side performs much better from a transparency POV than any metal or wooden coupling disc (a.k.a. speaker spike floor protector) I've tried for the application. It's very effective, and I think it will perform very well as an interface with the Neuance platform. I look forward to your findings if you might decide to give it a try.
I haven't tried that, but certainly will. Never got the chance this last weekend to try the disc/BDR/Grungebuster combo, so I have a number of things left to try. Thanks for the suggestion!
I think these are what's under the Nott' platform. I bought them so long ago I can't remember for sure. But then I can't remember what I had for breakfast either....
I recommend the use of this 40mm x 10mm carbon fiber disc with thin anti-skid pads adhered both above and below each disc, positioned between the two maple boards. You can experiment with various pads, but 40mm Herbie's Audio Lab Thin grungebuster Dots (black version with optional adhesive backing) perform very well for the task. For use under the turntable isolation platform, experimenting with a set of four, as well as a set of eight might be of benefit, since the rigidity and mass of many carbon fiber discs might be of sonic benefit, perhaps depending on the suspension of your particular turntable.
Thanks, Duster. In fact, I did some experiments with these exact discs -- having ordered a bunch when you first introduced them. Sonically, they didn't seem either beneficial or detrimental when used this way. And that may have had everything to do with my turntable's pretty substantial suspension, which is comprised of four cartridges containing springs in silicone fluid.
But, these discs were far from ideal in that I was forced to use them in stacks of three due to an additional consideration: whatever I use to elevate this isolation platform must clear the 7/8" brass caps in the four corners of the top shelf of my audio rack. When stacked this way, the carbon fiber discs made the ~100 lbs. above seem precariously balanced. Especially when you factor into the equation a couple of acrobatic felines with whom I cohabitate. The fact is that excellent lateral stability would add a lot of comfort, even if it doesn't contribute much to (or even detracts a little from) sonics.
Duster, I know that you like the Herbie's Audio Lab products, and I wonder if something like the "Extra-Firm Big Tall Tenderfeet" might work, here? I've also come across something called "MagicHexa" from Agora Acoustics (link below). Here's a description:
The MagicHexa Audio Vibration Isolation damper feet are made from a proprietary visco elastic polymer that combines shock absorption, vibration isolation and damping characteristics to create the ideal acoustic damper and absorber. Its specially formulated Vibration Dissipating Aerodynamic honeycomb Configuration have almost 1,000 times higher damping coefficient than metal, thus reducing the transmission of various vibration energies into whatever surface the component is sitting on.
With respect to lateral stability, I wonder if the honeycomb design might serve to "suction" my maple boards together?
Anyway! Continued thoughts would be most appreciated!
In my experience, combining two or more thick compliant (squishy) footers or pads in a stack can be counterproductive. A very compliant decoupling footer or pad should have a rigid surface to work against. If a thick compliant footer like the Big Tall Tenderfoot is placed under the maple platform, it might not complement the function of the compliant turntable suspension. In fact, the Big Tall Tenderfoot is suggested to replace stock suspension springs rather than augment their function.
I would suggest using a tall set of rigid metal cones or spikes if you need clearance below the maple turntable platform. You should also use a coupling disc under the tip of the cone or spike rather than simply allow the tip to dig into the wooden surface, which is not a very good way to couple a cone or spike to a relatively soft wooden rack shelf surface. The 40mm x 10mm Carbon Fiber Disc can also function as a very effective coupling disc by using the indentation on the one side of it to position the cone tip into, and will also add 10mm of height, as well as a couple of millimeters due to the thin anti-skid pad adhered under it.
Thanks, Duster! I think I get it: even one additional squishy layer is likely not to play well with my turntable's suspension; instead, you recommend that the suspension be the only compliant "layer" -- with everything else being rigid.
Would Herbie's "Hi-End Booster Bases," used in conjunction with the Grungebuster Dots (which I think you originally recommended), be an improvement over the Tenderfeet?
To your immediate suggestion, metal cones or spikes are certainly doable -- although that's not something I use and have around. If I were to start with what I have on hand, I could try either the old Polycrystal cones (lots of those around) or a set of Finite Elemente Ceraballs, which I'm thinking might conform to your suggestion:
Despite the employment of ball bearings, here, these devices don't shift horizontally like most bearings do. They're quite stationary. And as a result, I believe that they act very much like cones or spikes, with their functionality being almost entirely in the vertical coupling realm:
The CERA technology is based on direct coupling for effective transfer of sound interfering resonance. Fast resonance transfer is provided by extreme hard high-tech ceramic balls. Combined with precision machined materials like stainless steel or aluminum the optimum balance between damping and deflection is achieved. The resulting vacuum effect draws off unwanted resonance directly where it evolves.
Hmmm ... yea or nay? Could these be used alone, or should they be matched up -- top or bottom or both -- with the carbon fiber discs?
You know, it strikes me that, by adding this extra platform, I really don't stand to gain anything beneficial, and I've probably laid some traps for myself. Would shifting gears and looking for a way to raise the turntable, on its own, high enough to clear the top-shelf obstructions -- while directly coupling it to that same top shelf -- be the preferred approach?
This has gotten a bit too thorny for my limited insight/knowledge. Please know how much I appreciate the expertise!
You should be good to go, since either the Polycrystal cone or the ceraball Universal footer should perform well for the purpose. I would adhere a 40mm x 10mm Carbon fiber disc under either device with Liquid Nails silicone adhesive, with a 40mm Herbie's Audio Lab Thin grungebuster Dot (black version, with optional adhesive backing) affixed to the bottom of the disc as an interface with the rack shelf surface. The slightly rounded tip of the Polycrystal cone would be placed tip-side-up to make contact with the bottom of the turntable platform, with the carbon fiber disc acting as a base. The top of the ceraball Universal footer should also have an appropriately sized Herbie's Audio Lab Thin grungebuster Dot (black version, with optional adhesive backing) affixed to it to act as an interface with the bottom of the turntable platform, with the carbon fiber disc acting as a base. If I were to choose one vs. the other without comparing them, I would choose the ceraball Universal footer since the coupling function and potential beneficial vibration control may be better optimized for the purpose.
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