Sound (low frequencies) in a round pratice room?

[jokum]

I am currently struggling with the sound of a practice room for my band. Especially the low frequencies are a problem. The main difficulty is that the room is dome-shaped and entirely in concrete (it's an old 2nd World War bunker). Therefore we can't place

[doug osborne]

I don't know if enough bass trapping exists in the whole world to fix this...

 

Carve a rectangular room out of the dome-shaped room using broadband absorbers like you find at Real Traps and other places. Your fundamental problem is that all notes below 100 Hz or-so are ringing - most rooms just have two or three notes that cause real problems.

 

This is not something that egg crates, mattresses or acoustical foam can fix, since your problem is not high-frequency reflection.

[Ethan Winer]

 

Originally posted by jokum I am currently struggling with the sound of a practice room for my band. Especially the low frequencies are a problem. The main difficulty is that the room is dome-shaped and entirely in concrete

 

 

Even if the room is round bass traps will still help. In fact, that's your only real recourse!

 

--Ethan

[steveg]

Can you build new walls? i.e. frame out your own shape and perhaps make your own bass traps out of the frames themselves??

[philbo]

It may be helpful to find what frequency the dome resonates at. Try a slow frequency sweep with a sine wave and see where the room starts to 'sing'. Or clap your hands while micing it with a spectrum analyser. I assume the room will be large enough (since your band fits inside) that it will be in the bass or upper bass frequencies somewhere.

 

If the frequency is high enough, a tuned trap might be helpful. In the long run, though, you'll want to use a lot of broadband absorbers, as Ethan suggested. You might need to cover more than 50% of the exposed dome area to start seeing good results.

 

A dome is the worst possible shape for audio. It acts as a focusing mirror, so all the sound bounces back to the center focal point of the dome. You may want to consider putting a large bundle of fiberglass at the focal point, as a place to start.

[Lee Knight]

How about polycylindrical diffusers lining as much of the walls (wall ) as possible. They trap bass although not as efficiently as something like Ethan's designs. But they offer an additional advantage. They would destroy that horrible focus into the center of the room you almost certainly have. Your reflections would disperse instead of focus.

 

Cheap too. Just pinch 4x8 pieces of door skin plywood or the like between 2 trim strips. Some also find the bass trapping properties increase when you line the wall behind with 703. Just don't interfere with the panel itself as that needs to vibrate in order to absorb. Use foam stick-on weatherstripping where the panel meets the trim strip to prevent rattles and buzzes.

 

[thankyou]

We're thinking of building a circular house from a company called Deltec. I've been interested in domes for years, but this configuration seems more useful, troublefree and rapid. They claim to have never lost a home to hurricane or earthquake since the company was founded in 1968.

 

Anyway, we had thought of having the upstairs level as a primary living space and the walkout basement would be the music practice/studio area. Do any of you think that this bass resonance problem would occur in this type of construction. The space would be broken up somewhat with interior walls for a bathroom, control room and shop.

[Rudolf von Hagenwil]

Alternatives: Learn Violoncello, or Viola who has less low end. It certainly will sound good in the dome bunker. Of course, if it is a German bunker in the Bretagne, maybe additional exorcism helps too. One way or another, I'm pretty sure it has nothing to do with the dome nor the concrete

 

.