Sorbathane under granite slabs for speaker bases?

Well, transforming vibration to heat is what ANY constrained layer viscoelastic type damper does, but Sorbothane is not as good at this as many other materials for whatever set of reasons. Any major dude will tell you. Certainly Sorbothane doesn’t isolate down to 5 Hz. That’s hooey. In the overall scale of things I’m inclined to say Sorbothane is one of those materials a lot like lead that appears to be a good idea but in practice actually hurts the sound. Great for running shoes, though.

ebm
For the best sound look at Symposium Super Plus with spikes for cement floors or without for all wood floors, Granite rings and is tipped up for thin highs,Good luck though.

If you’re afraid that granite rings when you strike it, don’t strike it. When granite is placed on springs it’s isolated so don’t worry, everything will be OK.

When granite is used with springs you get the benefit of high mass and low resonant frequency - below 3 Hz if you play your cards right. As a bonus there are no resonance issues with granite since it's isolated along with the component, thus no reason to apply damping, always a plus in these delicate matters. The inexpensive way to play with the big boys. Certainly no reason to spend a fortune. The only issue for springs is center of gravity, I.e., tall heavy speakers might be too top-heavy to place springs directly under them. But there is more than one way to skin a cat. Subwoofers are ideal since they have low COG.

geoff kait
machina dynamica
isolation & resonance control

jl35
how much is the TMC ?

My guess is $5K new from factory. On their web site TMC makes the following statements. I know, it sounds like there's an echo in here, right?

"Granite Tops
Granite surfaces are standard with 64 Series tabletop platforms. They are available on special order with other isolation systems. The advantages of a granite top are its relatively high mass and stiffness and the potential for being lapped to a precise surface flatness. Granite’s non-magnetic nature is useful in some applications.

For small tops, granite is an inexpensive, moderate performance material. In larger sizes, however, granite is more expensive than standard TMC top plates, sacrifices damping, and does not have other desirable features."

The very expensive TMC isolation platform uses a thick granite top plate. I have used thick granite and bluestone with springs, sonically exceptional in every way. High stiffness and high mass on springs, cannot beat with stick. Granite cannot ring when it's isolated. Hel-loo!

The same reason Sorbothane is used for shoe insoles - shock absorption - makes it unsuitable for use in isolation devices since Sorbothane stores energy, preventing energy from rapidly exiting the system. Compared to what, you ask? Compared to say, Super Balls. Super Balls release energy very rapidly. Or very hard cones, which also release energy rapidly. It’s a subtle thing, the Sorbothane, but quite noticeable compared to real isolation. Tone incorrect, loss of dynamics, closed in sound. Ah, I remember it well.