Controlling Resonance - will this work?

[Jaco D]

My rig is in the basement - an amp, a 115 and a 210. Here's the thing. Even at low volumes, the galvanized steel duct work in the dungeon resonates at low frequencies (as expected). Will eventually finish the basement and will hide the duct work in the process when I have the free time to do so. For the meantime, I have to jerry-rig something to mitigate the resonance. This is what I'm thinking: will raising the cabs and have them fire down on the floor (it's cement by the way and not sound absorbing material like carpet) mitigate the resonance? I was thinking of making a stand that would keep the cabs off the floor yet have an unobstucted sound path to the floor (yeah, it'll look like a port-a-potty bench). If this works, how will the distance from the floor affect the cab's performance? Another thing I'm thinking of is to fashion something like a reflector in front of the drivers to re-direct the sound wave down.

I know, i could answer my own question by trying it out. however if someone out there who understands acoustics and knows theoretically this thing isn't going to work can chime in, then I could save an afternoon of moving things around (not to mention straining my back) testing something that's surely not going to work.

[rpsands]

It's very likely that the sounds that are making it resonate are omnidirectional. The fundamental and first harmonic of every note in first position is omnidirectional (and more IIRC).

So no amount of aiming or whatever is going to make a difference, at least not in my experience.

Damping the room can help a little but damping the actual object resonating is going to help more. Again, my experience talking.

Try putting your hand on the ducts to hold them still while someone plays through your bass. If that stops it, putting something on the ducts will stop it too.

[bongomania]

Instead of all that mechanical business, I would just use a parametric EQ to dial out the resonant frequencies.

[BassmanPaul]

Stop messing around and finish the damn basement! I can hear it rattlin' from here!

[Jaco D]

Originally Posted by BassmanPaul

Stop messing around and finish the damn basement! I can hear it rattlin' from here!

Paul, aren't you watching the Leafs tonight? *avoids a shoe thrown my way* hehehehe...

Originally Posted by rpsands

It's very likely that the sounds that are making it resonate are omnidirectional.

Yeah, that's what I was afraid of. Oh well.....

[billfitzmaurice]

Originally Posted by Jaco D

will raising the cabs and have them fire down on the floor mitigate the resonance?

Not one iota. The resonant frequencies are totally omnidirectional.

[62bass]

I've moved my practice room to the unfinished basement and I'm having the same problem with duct work resonating. You can get rid of some of it by eq which screws up your sound so isn't worth the bother. Playing quieter helps but also isn't enough volume most of the time. Raising the amps off the floor lessens bass and doesn't do much. I like the sound I'm getting. I just don't like the room noise.

The only thing that works is to dampen each resonating duct or panel. It's actually pretty easy and cheap

That's my nest project. I'm going to do it before I finish the room (if I ever do)

[rpsands]

Originally Posted by 62bass

The only thing that works is to dampen each resonating duct or panel. It's actually pretty easy and cheap

Just re-echoing this. It's not pretty but it is cheap and it's the best way.