I would appreciate your opinion and any suggestions concerning structural solutions/tips used to get the most out of a subwoofer. My home theater room (living room) has wood floors over a garage. The ceiling is vaulted and the walls are drywall/sheetrock. To further complicate matters, there are some old people on the other side of the house who live by the mantra "silence is golden" (yup, my parents still live with me!). I have heard of people using vibration-isolating products (stands/risers), like the Aurelex Gramma/Subdude, ASC's Subtrap, or even improvising with a slab of solid granite and rubber feet underneath in order to achieve tighter bass and reduce resonance transfer to the floor and walls. When I think about it, getting the subwoofer off the floor by suspending it seems to make sense. But would I still be feeling the LFE (25 Hz) as opposed to just “hearing” it? What do you think about this theory/solution and which product or method, if any, would you endorse without having to lower the subwoofer volume all the way or having to kick Mom and Dad out every time I want to watch a movie? Also, how high should I elevate the subwoofer? Would this solution also benefit forward-firing subwoofers? Thanks. – Justin.-----
Hi Justin,
Raising the subwoofer off the floor will reduce the direct mechanical transfer of low-frequency energy to the floor but, as you correctly surmised, it will also lessen the "feel" of the deep bass, which is partly transmitted through the floor and furniture. Lifting it off the floor will also reduce the total amount of radiated deep bass by 3 dB or more, because the subwoofer will no longer benefit from the boundary reinforcement of the floor itself. However, the real problem is the pressurized deep bass--the long acoustical wavelengths of air pressure that you actually hear as ultra-deep bass, and those account for the bulk of energy from the subwoofer. It's those that vibrate the sheetrock, wood joists and stringers, and transmit the energy to other parts of the house and building. That's why granite slabs, risers, subtraps and the like may help a bit in lessening the mechanical bass vibration but do little to absorb the acoustical energy. Bass traps are not a solution because in absorbing some of the acoustic energy, the subwoofer just works harder to generate more. Put another way, you'll just turn up the sub level to hear more bass because the bass trap is absorbing it! The only answer is to redo the room with specialized sound-insulating sheetrock such as QuietRoc (in demos, I've been impressed by this product) or to literally build a room within a room, which becomes impractical except with new construction. Here's a link to my article that includes links to suppliers of soundproofing materials
http://www.axiomaudio.com/soundproofing_pt2.html One solution adopted by one Axiom customer was to install "butt-kickers" (electrical motorized transducers that vibrate according to the LFE bass energy) in the couch. That way he gets some of the sensation of deep bass without having to turn up the subwoofer to levels that will disturb others in his home. You might also try posting on the Axiom forums, where other Axiom customers may have some tips that I've overlooked.
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