Originally Posted by GWCR
Depends. If you want the sub energy to travel directly into your slab/foundation and bypass your soundproofing, then go ahead. However, if you have taken the steps to do sound containment to your HT, I believe you would want to have the sub on a sand filled stage rather than directly on the concrete. If you have the right sub for your room, you'll still feel that sub (and shouldn't need bass shakers IMO...).
I've been questioning the same thing over the last few weeks as I've read builder after builder hauling thousands of pounds of dirt into their homes. On the one hand, you have to believe that so many people doing the same thing must be doing so for a good reason. But then again you have the cultists who cheerfully tell you to just drink the Kool Aid.
This is the one statement that I've read so far that makes me go "hmmm....".
IF the subs are on a concrete floor AND inside an otherwise sound isolated room with all the usual techniques you read about here (stagger studs, double wall, isolation clips, double drywall, green glue, clips and channels, acoustical caulk, plugging electrical boxes, tighter seals around doors, etc.) are the subs really vibrating the concrete slab itself (and by extension then vibrating the concrete walls, which would then give you your flanking path for sound transmission around your sound isolation perimeter)? Or is the usual modality for sound transmission the vibration of the drywall and studs of the walls being transmitted through to other framing members and then the floor of the room above -- in which case your sound isolation techniques should be effective at blocking?
Is there any benefit to the sand packed stage if one is using in-wall LCR's (i.e. full range, no subs)?
If mounting subs behind the screen wall, would there be any practical difference between putting them on a full (behind the screen) stage filled with sand vs. just a sand-filled platform the area of the subwoofer itself?
I assume that the touted benefits of the sand-filled stage is somewhat dependent upon a certain amount of mass, but at what point do you hit the point of diminishing returns? Is a 24" high stage filled with sand going to be more effective than a 6" high stage sharing the same footprint as the taller stage?