John Sayers' Recording Studio Design Forum Archive

I've heard that in small rooms like mine (14x11x9ft) bass traps should take the form of broaband absorbers in corners. Why is that the case?

A problem I see is that these broadband absorbers won't be able to satisfactorily addres low frequency 40-50hz -150hz problems. Panel traps might though. So why not use them?

arpit,

> I've heard that in small rooms like mine (14x11x9ft) bass traps should take the form of broaband absorbers in corners. Why is that the case? <

Because peaks and nulls occur at all frequencies due to comb filtering off the nearby surfaces. See THIS article I wrote for Electronic Musician magazine that explains in more depth.

> broadband absorbers won't be able to satisfactorily addres low frequency 40-50hz -150hz problems. Panel traps might though. So why not use them? <

Well designed "porous" absorbers absolutely can target frequencies that low.

--Ethan

A problem I see is that these broadband absorbers won't be able to satisfactorily addres low frequency 40-50hz -150hz problems

Look at figure 1 in BBC RD 1992-11. Absorption flat as known down to 40 Hz, the lowet frequency tested, for 280 mm thick "broadband absorbers."

Andre

wow, thanks
I made some plans for broadband absorbant traps to place on 2 wall-wall edges and 4 ceiling-wall edges. I've attached the picture. What kind of frequencies will these traps be useful for?

Cheers,
Arpit

Arpit,

> What kind of frequencies will these traps be useful for? <

As with all porous absorbers, they do less and less as you go lower. You don't show how thick the rigid fiberglass is, and that's the key. If you use six inches thick they will still be useful probably down to 40 Hz. More to the point, most rooms don't need as much absorption at 40 Hz as at higher bass frequencies.

--Ethan