Damping floor/ceiling room node?

[atledreier]

Hi!

What would be a good way to tame a floor/ceiling room node? Corner trapping has proved less effective than hoped.

I have plans to use 3pcs 4" 2'x4' panels suspended from the ceiling with a small gap (1"). Would this be enough? The node is at 73Hz. Where would I place the panels? I am planning to hang them in the 1st reflection points from fronts and center, and thought maybe I could swat two flies with one shoe. Any thoughts?

[bpape]

If you're sure it's height related, doing a panel over your head will help. 4" with a gap will definitely do something at that frequency. It may not get it all but it certainly will help.

Bryan

[atledreier]

I'm pretty sure. Node charts for my size room show a floor/ceiling node at 73Hz, and I have a null at around 70Hz that moves with height. Will panels anywhere help, or is there some preferred position to kill the node? I was hoping the 1st reflection damping would also help kill the node.

Maybe a helmholzt absorber tuned to my exact problem frequency should be considered too? Since it's a specific frequency. A 70-something box wouldn't have to be excessively big.

[Ethan Winer]

atledreier wrote:

Will panels anywhere help, or is there some preferred position to kill the node?

The best place to put absorption is where the problem bass frequency builds up the most. This article and test signal download might help you:

http://www.realtraps.com/lf-noise.htm

--Ethan

[bpape]

A tuned, sealed membrane absorber for that frequency is gonig to be 4"+ thick and still have to likely go right over your head. Also, the sealed wood ones like that are not nearly as efficient per square foot but it's an option.

Bryan

[atledreier]

Ethan Winer wrote:

The best place to put absorption is where the problem bass frequency builds up the most.
--Ethan

Ok, I guess this is the same as the subwoofer pink noise that REW generate? I might as well use REW, and take readings from multiple locations around the room?

bpape wrote:

A tuned, sealed membrane absorber for that frequency is gonig to be 4"+ thick and still have to likely go right over your head. Also, the sealed wood ones like that are not nearly as efficient per square foot but it's an option.

Bryan

Not as effective as what? A regular absorbing panel?

[bpape]

Yes. It won't absorb as much per square foot so they tend to need to be larger. Realistically, they need to be a bit larger anyway as the size of the panel can restrict the tension on the front membrane which can change the tuned center frequency. It's not usually a big deal as these will function over about a 1.5 octave band.

If you wait a little while, I believe there is a new version of REW coming out with an RTA function built in that will make your life MUCH easier.

Bryan

[atledreier]

I have trueRTA too, so I can do 'live' measurements. Will do that tonight.