Let me clarify: when I said "very few of them are truly rigid" I was referring to audio racks, not concrete slabs.
Concrete slabs don't vibrate in the audible spectrum, and almost not at all in the mechanical spectrum (below 12 Hz. or so) therefore it's unlikely, unless you live next to a railroad line or an interstate, that you'll have anything to contend with except airborne vibration from the music itself -- and that's really negligible, even for turntables, unless they're positioned right in front of a woofer (also unlikely I imagine?)
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Concrete slabs don't vibrate in the audible spectrum, and almost not at all in the mechanical spectrum (below 12 Hz. or so) therefore it's unlikely, unless you live next to a railroad line or an interstate, that you'll have anything to contend with except airborne vibration from the music itself -- and that's really negligible, even for turntables, unless they're positioned right in front of a woofer (also unlikely I imagine?)
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