Is a wooden platform for seating a legit idea to pick up tactile acoustic energy?

It's your theater, do what you will enjoy.

The span of the plywood will determine the resonant frequency. There was a great theater here in Toronto called the Uptown where they specifically tuned the seat platforms to ~40hz. Whenever movies had content around there the whole place shook. The main caveat is that it tends to sound the same after awhile.

Have you considered putting the wood platform on the bass shakers? It may be a more natural feel since your feet would also feel it and there wouldn't be that unnatural disconnect of feeling the coach move but not the feet. Just a thought.

there was a thread where this was discussed some time ago. i forget where on avs. the bottom line was that it can work, but it has to be 'lossy'. if the platform is built rock solid, then it may not provide any additional tactile sensation.

your post is a really good one in that it raises the question of how much ultra low frequency stuff is air driven vs. vibrational/tactile driven. i've been in an all concrete structure during earthquakes and within 100 feet of dynamite blasting. neither were very loud (well, the earthquake wasn't audible at all), but both really shook the structure. even a passing harley or dumptruck are very tactile through the concrete floor. i suspect someday we will have a 0.2 channel that carries tactile effects, but until then, we are left with a variety of compromises.

experimenting with some bass shakers attached to a lossy platform and crossed over (low passed) at something like 20hz or lower might get rid of the fake feeling that you describe.

edit: now that i think about it a little more, a cheap accelerometer attached to the floor might be a good way of measuring what you are looking for. even when i was within 100 feet of dynamite blasting, the spl never read much above 70db on my ratshack spl meter even though the whole damb building was shaking violently.

archea - i had the EXACT same quandry. Every time I'd go to my brother's house to test subs, I'd come home wishing my basement wasn't on a concrete slab.

I considered a platform, I considered butt-kickers.

The solution is actually much more simple IF you have multiple subs and room for it: place one sub nearfield immediately behind your seating, facing your seats.

I put my A7s-450 in that position, put the crossover on the amp at 50hz (anything higher is too localizable) and set it to run 6db quieter than the two subs I have up front next to my front mains. Those subs I crossed over around 150hz.

That setup allows me to enjoy the couch-shaking (and believe me, it is every bit as awesome as being on floor joists) effect without feeling like the bass is coming from behind me, I still get plenty of mid-bass slam from the front subs AND to top it off, the couch-shake effect is timed much tighter to the actual timing of the frequencies being played, so it's even more satisfying.

If you have circumstances that allow, give it a try.

My wooden platform for my back seats has much more tactile feel than my front seats which sit on a carpet over concrete. However, I like the bass better up front because it is just waves of bass hitting you and just sounds more natural than the riser platform.