Thanks for the interesting report.
When I was looking to my turntable from floorboard vibration - my equipment rack would ache like a bugger with any footsteps on the floor - I tested all sorts of materials.
The best I could manage was using “ vibrometer” Apps on my phone and iPad, which would show differences in vibration transfer.
The isopucks made some difference, but not a lot. As I mentioned earlier, spring based footers made a way bigger difference. They essentially killed vibration transfer dead.
Which is why out of curiosity, I ended up, trying some under my loudspeakers which sit on sprung wood floors in my listening room.
When I played music at approaching loud, and especially if there was bass, standing near the speakers I could feel the floor vibrating, and I could also feel the Ottoman on which I would place my legs vibrating as well.
When I put the Springs under the speaker, there was no vibration on the floor, and I didn’t feel that vibration on the Ottoman.
It all seemed to clean up the bass quality, and the sound generally speaking, but it also felt a bit odd, like I didn’t “ feel” the sound as much anymore. Kind of like what I get from electrostatics versus a good old box speaker.
I ended up buying some isoacoustic Gaia footers to get a sort of in between effect - they seemed to isolate enough to tighten bass and clean up the sound a bit, but still coupled enough so they didn’t totally lose that “ room feel” and impact.
I also also tried all sorts of layers of different materials as a platform beneath the speakers - some where commercial offerings used in some studios, which to me didn’t help the sound at all. (in most comparisons, I was being careful to keep the height of the speakers constant. )
I tried MDF, combined with different layers in between or on different spikes or footers. I ended up… for looks and simply to raise the speakers even higher as much as anything… building a thick granite base, with car sound damping in between the granite slabs, and that slab placed on short wide spikes into the floor. I think that was an exercise mostly in moving resonances around, not in getting rid of resonances. But the end result For me was just about perfect in terms of bass quality and tonality of the speaker, as well as raising the soundstage.
Here’s what I ended up with;
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