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DIY speaker isolation base for a wood floor

A definite sonic improvement in tightening up the bass. 
1. Start with 4 aluminum cones. I used some old Mod Squad Tip Toes.
2. 16x16 slab of granite.
3. 1/8 cork.
4. 1/2 inch neoprene rubber.
5. 1/8 cork.
6. Top with another 16x16 slab of granite.
7. Enclosed with a wood cradle to hide the mechanism.
  The granite is from scraps from a shop and was cheap. The added 1/4 inch of neoprene to 1/2 inch thickness did help. Let me hear your thoughts.
128x128blueranger
audiozenology
362 posts
 
  • Wood floor. Assume somewhat springy? ... then usually better to isolate.
  • Neoprene rubber of that surface area likely provides next to no isolation in the bass frequencies, and probably not much absorption. It is too stiff.
  • I expect the cork does not provide much isolation / absorption either. You have a large surface area and relatively low weight per surface area. That impacts the spring constant. Too stiff and you don’t isolate bass frequencies. You can get at least a bit of an idea by looking at how much it compresses when the speaker is on top. If it looks like it compresses little, then assume not much bass isolation. The problem with cork is to compress it enough to get a good spring constant for isolation, you will get to the point where cell walls collapse. w.r.t. Sound, cork is normally used for insulation, not absorption. It does not have the hysteretic losses needed for absorption unless used right in its sweet spot where it is quite good. Problem is ensuring you are using it properly.
  • The big granite pieces may be better transferring energy into the stiff joists of the floor. Added bracing under the floor where the speakers are can help too.
  • Replacing the cork/neoprene with well chosen sorbothane pucks/squares will be quite a bit better. Need to take into account speaker/platform weight, sorbothane type, and surface area. Thicker will provide more dampening. Let me know the weight of your speakers and I can give you some direction on the hardness / surface area of Sorbothane to use.
  • Springs will provide more isolation, but again, they must be carefully selected to get the frequency below the audible region.
  • Best would be a combo of springs and sorbothane to both isolate, and then damp speaker motion. Best of both worlds.

    • Post removed 
    blueranger's avatar
    blueranger OP
    719 posts
     
    My speakers are 75 lbs plus 2 16x16 granite slabs. Thanks!!!
    clearthink
    1,421 posts
     

    geoffkait    "    I agree cork is a wonderful audiophile material"

    I think that the reason many people reject, undervalue, or discount cork is that it is not a engineered man made material so for those who like to read, analyze, and assess product information sheets it does not offer the same satisfaction. However for those who actually have "real world" experience which means doing, testing, and listening and not just reading and "calculating" it can be very useful, effective, and advantageous.  
    bdp24's avatar
    bdp24
    9,800 posts
     
    Anyone looking for rubbery damping materials has a couple more to choose from: EAR Isodamp (used in industry) and Navcom (used in the gun business). One form of Isodamp is made expressly for constrained-layer damping, another for damping of metal parts such as electronic enclosures. Michael Percy Audio sells both. 
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