Hi all,
I hope someone can point me in the right direction with this two-floor building I have. The problem is the bass transferring from the rehearsal studio downstairs to upstairs.
There have been no special construction techniques employed, so I know I'm not going to be able to solve the problem completely. However, the bass upstairs seems quite a lot *louder* than the bass downstairs (where the subs are).
This is what the construction of the second floor looks like:
The truss height is 2 feet and the building is 70ft long, 30ft wide.
The ceiling of the downstairs rehearsal studio is concrete or plaster or something, it's attached to the bottom of the trusses with a metal mesh and REALLY heavy. Looking down onto the top of the ceiling it looks like this:
Recovered from web.archive.org — originally hosted at http://inspectapedia.com/interiors/Plaster_lath021-DJFs.jpgThere are also a few holes in the ceiling where the 2ft "crawl space" is exposed.
I've done a little reading on the subject and it appears the "crawl space" may be acting as a resonant chamber. I have also noticed that there is a slight delay between the bass being heard in the PA and it shaking a load of stuff upstairs.
My first question: Is my supposition right?
Second question: Anything I can do about it, short of demolishing the building and starting again?
thanks in advance for your help!
I've done a little reading on the subject and it appears the "crawl space" may be acting as a resonant chamber. I have also noticed that there is a slight delay between the bass being heard in the PA and it shaking a load of stuff upstairs.
Very probably, that is what is happening. the delay is the giveaway: It takes time for the resonance to build and reach the point where it amplifies, since system is very massive. I'm also guessing that when the bass note stops suddenly, the resonance continues on for a short time, probably several hundred milliseconds....
Second question: Anything I can do about it, short of demolishing the building and starting again?
It's not going to solve the problem entirely, but it might help: you could fill the cavity completely with something like OC-703, or something similar.
- Stuart -
