Room Treatment Options?

Soft treatments are indeed velocity absorbers - not pressure absorbers. Again though, it's not a black and white issue. You'll get OPTIMAL absorption at 1/4 wavelength of the frequency in question (distance from hard boundary to leading edge of absorption) but you'll still get some behind that. Thickness also does make a lot of difference. Again though, thinner can still do some good.

As an example, our Monster panel is 8" thick (6" absorption with an airgap built in). Theoretically, you'd get diddly down low. Testing shows that at 50hz and a flat wall mount, you'll get 0.18 coefficent. Corner mount will give you a 0.63 coefficient. Now, I do have to caveat that since there are NO standardized measurements below 125Hz and there are no standards for corner measurements. All we can do is show the sabines absorbed in the same lab room by the same samples on the same day. Still, it gives a decent relative idea.

Even with all of that, I've seen Monsters and even 244's and equivalent from other manufacturers placed behind speakers (SBIR) and on the rear wall (cancellations based on wall to head distance) have close to double digit impacts on frequency response aberrations.

Bryan

I hate to burst your bubble, but I'm going to disagree with just about everything you said in that last post.

What happens below 80hz is the fundamental of the music. No, it doesn't happen tons in real life but MUSIC doesn't happen in real life. It does exist though. And believe me, it's a LOT more than just pipe organ. Now, if you wanted to make this same kind of statement for below say 35Hz, I'd agree with you. But, there's a ton of stuff in music and movies that is between 35 and 80Hz.

Lots of thin panels is better than fewer thick ones - couldn't be farther from the truth.

Lots of bass traps? Depends on the size of the room, the shape of the room, the usage of the room, and the construction of the room. You're better off to determine WHERE the issue is and do that rather than just randomly placing lots of bass control around the space.

Panel absorbers can be relatively effective. They work over about 2 octaves rather than a few notes like a Helmholz. That said, their efficiency per unit area compared to broadband absorbers is in general, less than 50% over much of their range. Also, when you try to use them for VERY low frequencies, they can cause issues of their own. This isn't even mentioning the cost to build them.

You can build panel absorbers till you're blue in the face but if they're not in the right places in the room, you're reducing their efficiency even further. What if it's a height issue? Putting them on the back wall will help a little, but not optimally, and you may cause other problems by doing so. Get out the scalpel, not the shotgun and figure out why you have that peak and null. As mas pointed out in another recent post, you can use a piece of broadband absorbant moved carefully around the mic position and watch what happens to the peak and nulls to get an idea of where things are happening.

I will agree with you on one thing - concrete rooms suck! :hissyfit: They provide absolutely zero, zip, nada, help in taming bottom end. They're bright and edgy in the upper mids and highs. They generally require a lot more overall acoustic treatment than a 'normal' drywall over stud room with carpeted floor.

Bryan