Devilboy, spikes when placed under speakers, are for mass-coupling the speakers to the floor. Nothing more, nothing less. As I said, you could bolt the speakers to the floor and acheive the same thing, maybe better! The speaker designer engineered his speaker as if it would be operated in a COMPLETELY RESTRAINED state -- the specified performance of the drivers he used depend on it! If you say things sound better than with the spikes going through the carpet and into the floor, I would offer that the granite slab is now probably bridging across the joists underneath, whereas before, without the granite, and unbeknownst to you, the spikes just happened to be landing on one of those weak places in the floor, as I described in my post. I can't tell you how many times I've seen audiophiles fooled by not recognizing this oversight! (Same comment applies to Stereo5's experience.) You guys should go back and review exactly WHERE on your wood floors the spikes were originally landing, relative to the joists underneath -- and then reposition the speakers as I recommended! Then you can tell me about how great the granite works;--)
As for the comments about
vibrations travel down the cabinet, through the spikes, into the granite. Then, those vibrations bounce off of the granite, travel up through the spikes and back into the cabinet.
that is just patently impossible! The whole point of spikes and cones (especially when used under electronic components and turntables, etc.) is to act as MECHANICAL DIODES; meaning vibrations travel out the pointed tip, but CANNOT return back the other way! If the speaker cabinet is vibrating, either the designer meant it to, as in many of the English bookshelf speakers, or, more likely, the enclosure is inadequately braced! The only "vibrations" a speaker should produce are the ones from the drivers when coupling them to the air!
Further, you are certainly doing your speakers no justice by placing them on a "carpet sandwich"! I don't care if the granite slab weighs 500 lbs! It will still allow the speaker to rock. Even a few micrometer 'squish' at the speaker's base, will translate into a few millimeters of sway at the top of the enclosure (you know, where the tweeters are located?) and that is enough to cause doppler distortion in the high frequencies coming from those tweeters.
Go back and examine your floors and determine the location and direction of the joists. Then position your speakers as I indicated and I guarantee, you'll get better performance than you have so far -- that's for sure! All that speculative pseudo-science is the devil! -- only physics will set you free ;--)
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