[drphoto]

The big problem with my room is slap echo. I know I need to get some sort of midrange on up adsorption panels, but how would I know if I need bass traps? The sound system is in a balcony that overlooks my photo studio. The balcony area is 20Wx25Lx8H. The audio gear is on the wall facing the studio, which comes up only waist high. The studio itself is 20Wx60Lx20H (that's right 20' ceiling) It's all sheetrock w/ a concrete floor. The floor in the balcony is covered w/ industrial type carpet.

It seems like the problems I've read about w/ bass are in small rooms.

Speakers are Onix Ref One, which are standing in for my Merlin TSM-M's that are out for upgrade. Current sub is a fairly anemic Mirage BPS-150i.

Thanks

[zybar]

Everybody needs bass traps!

I'll leave it to Ethan, Bryan, or some of our other professionals to explain why.

I know that every room I have installed acoustic treatments (including panels designed for the bass region) it has substantially improved the sound.

George

[macrojack]

You need a big horn based sound system. Those little toy speakers can't properly serve a space with those dimensions. Bass traps are meant to keep the lengthy low frequency waves from canceling themselves on the rebound in smaller spaces. I imagine the need for them diminishes in direct proportion to the increase in room size. You've got 24,000 cubic feet. The average listening room is more like 2000 or 2500 cubic feet.

[Vapor Audio]

A room that big, your smallest dimension corresponds to under 30hz 1/2 wavelength ... most rooms you're talking about bumps/suckouts in the 60-80hz range because of room dimensions.  Because of that, bass traps are less important in your room. 

I actually did an install in a room very similar to yours in dimension and reflection of surfaces, this rooms was a log style design ... hardwood everything and very reflective.  He also had some slap echo in the room.  His is a cathedral ceiling though, a flat ceiling would have been worse due to another parallel surface.  I did a fair amount of measurements in that room and honestly couldn't find any significant bass issues.  I also found that most of the reflections were coming from the floor, and talked him into putting down a BIG thick rug with some carpet padding underneath for extra absorption.  He didn't want any room treatment panels, so we put up thick curtains on every window and on the sliding glass door at the back of the room.  After that and the rug the room was night and day better.

[Ethan Winer]

Bass traps are meant to keep the lengthy low frequency waves from canceling themselves on the rebound in smaller spaces. I imagine the need for them diminishes in direct proportion to the increase in room size. You've got 24,000 cubic feet. The average listening room is more like 2000 or 2500 cubic feet.

Exactly. With large rooms like that bass problems manifest more as reverb than peaks and nulls and ringing. But there's still a need for broadband absorption that works well to lower frequencies. The problem is different for a large room, but the solution is the same.

drphoto could start with thinner absorption that targets mainly the mid and high frequency echoes he hears. But most likely once that is done the boominess and reverb at low frequencies will be even more obvious. This is why broadband absorption is best for rooms of all sizes. When we treat bars and restaurants that have live music (or even just a DJ), we always include bass traps as part of the treatment plan.

--Ethan

[hmen]

Everybody needs bass traps!

I'll leave it to Ethan, Bryan, or some of our other professionals to explain why.

I know that every room I have installed acoustic treatments (including panels designed for the bass region) it has substantially improved the sound.

George

I agree with George, there are very few, if any, perfect rooms out there. Unless your room was designed specifically for listening to music I'm sure you need them. I didn't know I needed them until i put them up and heard the improvement. The change wasn't subtle.

[Ethan Winer]

Unless your room was designed specifically for listening to music I'm sure you need them.

Just to amplify this, even rooms that are designed specifically for music need bass traps and other acoustic treatment. Some people wrongly believe that having ideal dimensions avoids bass problems and the need for traps. But even a "perfect" room still has peaks and nulls and strong resonances that ring out and decay over time.

--Ethan

[bpape]

Just remember that there's more to treating a room than just frequency response.  You might get lucky and have relatively smooth response but the decay times and ringing in the bottom end are still there and masking details in the music.

While smaller rooms do require PROPORTIONATELY more bass control, larger rooms will still benefit from the inclusion of more broadband treatments.

Bryan

[srlaudio]

One problem you will encounter in a large space is that absorption of low bass energy requires LOTS of space and material to achieve success.  Mix in some LARGE diffusors, and you will be astonished at the results.  There is more than one way of counteracting standing waves and flutter echoes.  A concept of sound that I learned from the combined lengthy discussions with Rupert Neve and Elliot Scheiner, is that the role of psychoacoustics is a relevant and little studied effect.  The essence of these conversations was that if you affect the harmonics of a specific frequency, the fundamental changes in level.  This why I have had success with bass standing waves using diffusion instead of absorption.  I know this is an advanced concept not covered in the normal discussions here, but I can assure you that I have seen it work, in a great way, in the toughest environments in audio.  I urge you to keep and open mind, and look at what the leading installations in the world are using to address their acoustic problems, and formulate your strategy based on that. 

[gedlee]

While I would generally concur with diffusion over absorption, I do have to question this approach at LFs.  To difuse a wavelength some 20-50 feet long would take a difuser almost as big as the room itself.  Rooms with furniture ARE diffusers at these wavelengths.  So in practice the use of diffusers at LF in small rooms is simply not a viable approach.  You have to use absorption - a lot of it at LFs.  BUT you have to be careful NOT to overly dampen the HFs above a few hundred Hz.  This is the challenge.  I actually make about 1/2 of the rooms walls into panel absorbers which are rigid to HF, by move and absorb the sound at LFs.  Then spread a few subs around the room and things are great.  DO NOT overly absorb the rooms reflections as dead rooms don't sound very good.  DO use diffusers as much as possible at the HFs.

[Vinyl-Addict]

DO NOT overly absorb the rooms reflections as dead rooms don't sound very good.  DO use diffusers as much as possible at the HFs.

So how do you know you've gone too far with absorption or installed too many bass traps? Is there a line drawn that clearly states when you've gone too far?  I've heard some audio rooms that were just way too live for my liking but at the same time the owner has no problem with it's livliness. I think I could listen to a room more live than dead but finding the sweet spot between the two is where I'd like to be.

[Ethan Winer]

So how do you know you've gone too far with absorption or installed too many bass traps? Is there a line drawn that clearly states when you've gone too far?

There is no line. As far as I'm concerned it's not possible to have too much bass trapping. It is possible to have unbalanced absorption, where the decay times in one range are very different from the decay times in another. And that can lead to unbalanced sound. If bass rings for half a second but the midrange decays quickly, there will be more total energy at low frequencies simply because they linger longer. But that's a different issue from how much bass trapping is too much.

Bass ringing is at least as damaging as peaks and nulls. If you play a two-note chord on the upper range of a piano it sounds clear and pleasant. Play the same two-note chord a few octaves below middle C and it sounds like mud and neither note is clear. That's what happens when a room rings at bass frequencies. The current bass note clashes with previous notes that are still sounding due to ringing.

No domestic size room will ever be perfectly flat and with no ringing. So the more bass traps you add, the closer to flat you'll be. And the less previous bass notes will linger. I have 48 panels in my 25 by 16 foot living room, and the sound quality is excellent. The mids and highs are perfectly clear, and the bass is incredibly full and tight.

I've heard some audio rooms that were just way too live for my liking but at the same time the owner has no problem with it's livliness.

"Too live" is more a function of mid/high frequency decay time. This is easily tamed with relatively thin absorption. Or diffusion if you want to keep some liveness but have it be "good" liveness. Personally, I do not want a lot of room tone in my listening room. It just makes the sound from the speakers muddy and loses detail as the reflections combine with the direct sound you do want. But you don't want or need anechoic either. From my perspective, the best "formula" is to have as much bass trapping as possible, and absorption at all early reflection points. That will clean up the sound, yet the room will still be reflective enough for sound sources other than the speakers to sound natural.

--Ethan

[srlaudio]

Ok y'all....I have mentioned that large diffusers work better, and that they are dictated by higher prime numbers in the formula.  The typical diffusers seen around here are LOW prime number of 7.  We go much higher in our designs, and here is a link to some supporting information.  Keep an open mind!

http://www.digidesign.com/index.cfm?langid=100&navid=49&itemid=30591

[BobM]

If your room sounds like you are walking past one of those Honda Civic ghetto blasters pumping out bass heavy rap, then you need help (in more than one way). But seriously, even if you don't hear any "problems" with boom or frequency peaks/drops (and some degree of those are a certainly in any room) you may still find that appropriate absorption and diffusion will improve the imaging and stabilization properties of the system.

Enjoy,
Bob

[woodsyi]

I would like to see my wife's facial expression if she saw me decorate my walls like this.   

[Big Red Machine]

I would like to see my wife's facial expression if she saw me decorate my walls like this.   

...and her reply:  "YOU dust it!"

[Vinyl-Addict]

I would like to see my wife's facial expression if she saw me decorate my walls like this.   

Welcome to the Batcave. 

[Ethan Winer]

Ok y'all....I have mentioned that large diffusers work better, and that they are dictated by higher prime numbers in the formula.

I'm totally with you Alan, but just look at the WAF comments here so far.

--Ethan

[woodsyi]

To be fair,  Alan's diffuser fares better with my wife.  It's 6' wide x 4' high x 9" deep and really locks in the sound stage up front.

 

[Rob S.]

Hey Woodsyi...  that big panel looks like a bass panel not a diffusor....Is it a diffusor that covered with fabric?   I'm probably just confused as usual.

Rob S.