Can traps hurt acoustics?

[snyderkv]

MLO,

Is there a benefit to acoustically treating one side of the room and ceiling? I heard that anything other than front wall acoustics were much harder to notice and that symetry was important.

That being said, would it benefit to treat one side of the room and ceiling or is it possible to negatively affect acoustics as well? The room is 10W x 15L x 9H

I could hide maybe 6 panels in my room, some of them being acoustical art treatments from acoustimac.com

Any advice?

 

[amey01]

Of course they can hurt acoustics. Better to go slowly than quickly.

Start off with a few and go from there - and make sure you are hearing improvements rather than just differences.

And yes, symmetry is important; unless you want some funky sounding things (or unless you are treating a specific non-symmetric issue in your room of course).

 

[Rich]

Treating just one side of the room is a bad idea . . . unless there is a particular acoustic problem that can only be solved by treating one side of the room. While there are lots of general rules regarding treatments, each room is individual and should be treated as such (pun intended). The purposes of treatments are to reduce early reflections so you don't get smearing, comb filtering, and other acoustic anomalies which interfere with imaging, and also to absorb bass waves so you don't excite room modes. You need specific types of treatments in specific places in a room to do a good job on both these fronts. Just throwing treatments in a room willy-nilly isn't going to necessarily improve sound and in fact could cause more problems than it solves. For Martin Logan speakers, I suggest treatment of the back wave of the speaker (meaning an acoustic panel on the wall directly behind each speaker) and treatment of the side wall first reflection points with general purpose absorption, and then as many bass traps as you can fit into the corners (any corners, including wall/ceiling and wall/floor corners). This will achieve your goals.

 

[MPS]

Room treatment should be done by first analyzing the room and then finding proper solution for each issue. Acoustic elements should be located to where they are most required and type chosen by properties required for that specific location/purpose.
Typically bass traps/wide bandwidth damping to room corners and lighter damping to first reflection points. Right type of elements in wrong place and wrong type of elements in right place don't do nothing much for you.

 

[sleepysurf]

...treatment of the side wall first reflection points with general purpose absorption...

Rich, why the recommendation for side wall first reflection point absorption? Doesn't the dipole (figure-8) radiation pattern of ML stat panels mean there is little, if any, lateral dispersion?

I understand the need to do so with dynamic speakers, given their greater lateral dispersion.

 

[RUR]

I've found ipsilateral reflections (right speaker to right sidewall, left to left) with the ML dipoles to be non-problematic and so use no absorption. OTOH, contralateral reflections (left speaker to right sidewall, right to left) adversely affect imaging, so I do use absorption at those points.

Lots of subjective preference involved, so YMMV, etc. etc.

 

[Rich]

Rich, why the recommendation for side wall first reflection point absorption? Doesn't the dipole (figure-8) radiation pattern of ML stat panels mean there is little, if any, lateral dispersion?

I understand the need to do so with dynamic speakers, given their greater lateral dispersion.

ML speakers have very little vertical dispersion. They all have a 30 degree lateral dispersion. Which means first reflection points on sidewalls can be an issue and need some absorption. Every room and setup is different, so it is really necessary to try different things to see what works best in your particular setup. RUR's post above is a great example. He identified the problem reflections in his room and put absorption in those spots to rectify the issue. Given the thirty degree dispersion of MLs and the degree to which most of us toe them in, I fully agree with his assessment that contra lateral reflections are much more of a problem than ipsolateral reflections. But all of that will depend on things like size and shape of the room, distance between speaker and side walls, distance between speaker and listener, amount of toe in, etc. Lots of variables, which means lots of experimentation to get it right in your particular room.

I would note the OP's room is very small -- ten feet wide by fifteen feet long, so sidewall reflections may be a bigger issue for him than for someone with a much larger room.

 

[snyderkv]

Cool thanks for the responses.

I really don't know how to identify issues though as I can't see sound waves. The room itself has no echo and has sound proof materials under the hardwood and walls since it's a luxury condo so there is no telling if I have a problem to begin with.

I can't put anything behind the EFX speaker mains bolted onto the sidewalls because there is a scope projector screen hanging behind it although the speakers are 2.5" from the back wall so it may not be an issue.

I guess I'll have to pass on room treatments since I can't exactly audition before I buy or determine if I even have a problem. I'll end up upgrading to Audyssey xt32 and see if that will do some better correcting than placing huge traps around the living room and effectively turning it into a theatre/studio.

 

[sb6]

With Martin Logan speakers, contralateral reflections are almost non-existant unless you have an extremely deep room because of ML's limited 30 degree radiating pattern (as mentioned earlier in this post). I would also add that absorption can have deleterious effects when used on the front wall behind the speakers and diffusion for some is a better choice, albeit often more tricky to apply effectively.

 

[Rich]

I would also add that absorption can have deleterious effects when used on the front wall behind the speakers and diffusion for some is a better choice, albeit often more tricky to apply effectively.

Strongly disagree. In most normal-sized listening rooms, diffusion simply doesn't work. Absorption is a MUCH better choice. My room is 14' x 19' and I experimented with no treatment, with diffusion, and with absorption. Absorption wins and its not even close. If you don't dampen the back wave of the speaker, and if you don't have a large enough room to bring the speakers five or more feet from the front wall, then you will have reflections that will muddy the sound and ruin imaging and soundstage. Obviously, each room is different and experimenting (assuming you know what to listen for) is the best way to proceed. But the original poster's room is 10' x 15' and in that size room, diffusion would have no discernible effect. Absorption is required in that situation.

 

[sb6]

Strongly disagree. In most normal-sized listening rooms, diffusion simply doesn't work. Absorption is a MUCH better choice. My room is 14' x 19' and I experimented with no treatment, with diffusion, and with absorption. Absorption wins and its not even close. If you don't dampen the back wave of the speaker, and if you don't have a large enough room to bring the speakers five or more feet from the front wall, then you will have reflections that will muddy the sound and ruin imaging and soundstage. Obviously, each room is different and experimenting (assuming you know what to listen for) is the best way to proceed. But the original poster's room is 10' x 15' and in that size room, diffusion would have no discernible effect. Absorption is required in that situation.

What types/method of diffusion and absorption did you try? ALL to confidently state that diffusion is ruled out?

I have also experimented (not with all combinations in all layout configs) with diffusion, absorption and no treatment and found that a combination works best. I do agree (as stated earlier) that for smaller rooms, diffusion is likely not an option due to inherent early reflections with/without diffusion. Diffusion is much more difficult to get to work right, so most people just reduce reflections rather than scatter them.

 

[Rich]

What types/method of diffusion and absorption did you try? ALL to confidently state that diffusion is ruled out?

I used RPG Omnifusers (a quadratic diffuser panel) vs. bare walls vs. real traps panels (treatments mounted on the wall directly behind the speaker panels). My speaker panels are about 3 foot from the front wall and 2 foot from the side walls. Listening position is about 9' from the front plane of the speakers. In my 19'L by 14'w room, absorption panels directly behind the main speakers won by a long shot. In most rooms my size or smaller, I expect that will be the case.

 

[sb6]

Your speakers are very close to the side and front walls so you have no choice but to absorb it. That's not a typical layout especially for your size room IMO, unless you have some placement limitations. If you had adequate distance from side/front walls, your situation may be different (e.g.: QRD Diffuser which are more commonly applied than RPG Omnifusers for mid sized rooms). Also, in your situation, I'd be more concerned with bass management than with rear reflections.

Now that we're way off the original ML-er's topic.....

 

[twich54]

I tend to agree with Rich here. After thirty years of dipole speaker ownership I've come to the conclusion that unless you can give them the proper room to 'breath' (min 3-4', preferred 5-6') no amount of room treatment will work the perfect miracle

 

[sb6]

For reference - mine are ~5 1/2' off the front wall. Anything less than 3' and you are doing the speakers and yourself a disservice. I also recommend you read this bit of information on dipoles. Apparently, Quad and I agree.


http://www.theabsolutesound.com/answers/249/

 

[twich54]

sb, understood, but remember, you're at an ideal distance so diffusion to suit your personal taste makes sense. As a general rule I've preached for years the further away one gets the less absorption and if desired more diffusion. I also believe a min of 4-6' behind the listening position with 6-10' being even better !

 

[sb6]

Agreed, Dave. I think we're all really saying the same thing. I am fortunate enough to have enough space behind and beside the speakers to have options for treatment.

 

[Rich]

Anything less than 3' and you are doing the speakers and yourself a disservice.

Trust me, with the proper absorption behind the panels it is not an issue. My system exhibits exceptional clarity, detail retrieval, sound staging and imaging. I have listened to enough ML systems in enough different rooms to know what they are capable of and I couldn't ask for much more than what I'm getting. Certainly five foot or more from the front wall would be better, but that's not possible in my current setup.

 

[sb6]

Trust me, with the proper absorption behind the panels it is not an issue. My system exhibits exceptional clarity, detail retrieval, sound staging and imaging. I have listened to enough ML systems in enough different rooms to know what they are capable of and I couldn't ask for much more than what I'm getting. Certainly five foot or more from the front wall would be better, but that's not possible in my current setup.

I've also listened to my fair share of MLs in many different size rooms at various speaker positions and in a word - depth. I'm sure your system sounds great but it's impossible for you to achieve any significant depth at ~3' which is part of sound staging/imaging. In any case, happy listening!

 

[Rich]

I've also listened to my fair share of MLs in many different size rooms at various speaker positions and in a word - depth. I'm sure your system sounds great but it's impossible for you to achieve any significant depth at ~3' which is part of sound staging/imaging. In any case, happy listening!

Actually, with the back wave dampened and listening only to the front wave of the speaker, I get a very natural sense of soundstage depth and the acoustic signature of the recording space, when such cues are included in the mix. I am not a fan of the illusion of a huge and unnatural sense of depth created by the back wave reverberations, which make every recording sound like it was recorded in a large concert hall. Like a euphonic tube amp, it sounds pretty for a little while but soon you realize that it isn't an accurate rendition of the recording. Depth should only be perceived when the recording engineer intended it to be. Otherwise, you aren't really enjoying the performance as intended. You are instead enjoying a sonic distortion created by the acoustic anomalies of a dipole speaker interacting with the room. I understand that some people enjoy that. I prefer accuracy and realism.