Isolation for a table for floors with movement

Dev,

thanks for the details on your set-up.

from what you say it sounds like the floor is the way it's going to be. the only other 'floor' idea is to get something large, dense and heavy and try it under your rack. it's possible it might 'ground' the floor sufficiently to reduce flex. but it also might make things worse.

so what you can do is to address sources of resonance in the room which will transmit feedback, which is primarily your speakers. there are a number of de-coupling footers or platforms which can somewhat isolate the speaker feedback from the floor. right now you likely use spikes into the subfloor thru your carpet for the speakers.....which effectively transmit the speaker feedback.....you need to go the opposite direction and decouple somehow. then listen. it might be that spikes into the floor are best, but not likely while playing Lps.

then i think you are on the right track with the various multi layers of isolation you have mentioned. you might speak to TW Acoustic and see what they recommend for that tt in your situation.

good luck.

If the wall is out - how about the ceiling ? Is there a possibility to mount a kind of hanging suspension to the ceiling - 4 points. Each point would only have to hold about 25 - 30 lbs - most larger modern ceiling light devices are in that weight range. It would - in any case - be the most smart, inexpensive and effective isolation from floor-transmitted vibration. And sure can be an eye-catcher....

The stands to own HRS, Stillpoints, Finite Element - a used one on gon now. If you are going for less costly approach Arcici makes two satnds a Reference and Standard that very excellent. Excluding the HRS which is IMHO the best and most expensive stand out there. If you buy an HRS you'll never need to replace it.

For stands others than the HRS, I like adding a 1" slate or a SRA platform to the top on the stand for additional mass loading underneath your TW Acustic Raven. Congratulations, a super table!

Thx for the info.

My MBL 101E speakers are placed on Sistrum platforms.

Are the HRS stands really that good and the answer? They appear to be a ridget design, I wouldn't want to spend all that money and then have to still use on platforms etc.

What you guys think of doing this;

Remove the drywall below on the ceiling and box the joist in with plywood and repair. Then from up stairs remove enough finished flooring material and drill a hole in each joist run and pump in concrete. The joist are 12 inches so I could make it what even.

The joist are on 16 inch centers and my speakers are 6ft from the back wall so I could do say five runs.

thoughts on doing this

From a builders perspective, you are on a road towards disaster with that plan. Concrete is extremely heavy and needs to be engineered and built with steel rebar to be self supporting with a load. This is not the kind of thing you do with wooden joists incorporated
in all probability, your floor is fine since it is already over engineered from what i can tell. Two layers of 3/4 plywood is not normal procedure. If you have I-Joists, they are very rigid also.