Acoustic TReatments - What, How much, & Where?



Hello all you room treatmentfiles.

Being at the point where I probably should have begun, now, I want to 'treat' the room, acoustically. Economic reasons say I might have to go by way of ‘foam’ stick ups on the wall, but I’d really rather not. The desired alternative, however, is panels, and they are mighty pricey. OK.

Reading over the online info at various panel makers websites, (ASC, RPG, GIK, etc), some panels have different ranges of absorbtion, reflection, etc. according to the makers.

Q: How do you know just the amount of absorbtion, or diffusion to incorporate into the room via panels, traps, etc.?

Is there some Rosetta stone that will decrypt this for me… or is it all “trial & ear-ror”?

GIK panels seem the most feasible cost alternative, presently.

Any suggestions or related experiences in regard to sources for, or treatments of, will be more than a welcome thing.

Thank you
blindjim
Shadrone, In reference to your first sentence. I must say I'm at a loss as to the nature of the common 'misconception being purpetrated' here, unless of course you believe that setting up the speakers as you have described, or as you have in your systems photograph, is the definitive or only way of setting up speakers and there is only one possible end result.

In my experience there are many ways of setting up speakers which present a satisfactory stereo image to a particular group of listeners. I'm not talking multi channel, home theater systems, which is an entirely different issue/sound. Just simple two speaker stereo.

My personal choice is a sound which is pinpoint source specific which reproduces most accurately the sound of the recording. This requires exacting set up (as far away from all walls as possible, especially the rear wall, having a triangulated listening position, and the elimination of as much of the room's reflected sound as possible, including (most importantly) deadening as much as possible 1st reflection points. This set up, properly executed, gives you exactly what is on the recording, nothing more, and little less. I reemphasize that is my personal choice and when I discuss set up, that is my point of reference. I don't care much for a set up which presents a larger 'apparent' sound stage by utilizing room surfaces. Again, MY choice - MY preference.

Many folks prefer a different sound (whether they really even know that they do because they may have never actually heard a set up as I descrbibed) and that is a 'bigger apparent sound stage'. This will include a good sense of presence of the musicians between the speakers and as well, provide for a greater sense of ambiance created by the reflected sounds from room surfaces. In fact this sound is so preferred by so many that speaker manufacturers make speakers to specifically produce that result, such as panels, many electrostats, bipolar's using dynamic cones, as well as Omni's.

Now regarding the 'in-phase' and 'out of phase' issue. You have admitted that the information which comes from the outsides of the speakers is out of phase with the direct sound between the speakers (as I stated in my post), but you conclude that in a perfect set up it is in-phase with itself and does not effect the quality of the central stereo image. I have no problem with that statement in itself (other than I don't agree that it doesn't effect the quality of sound from the recording), however I fail to see how in any way it supports your statement about someone perpetuating (I think that is the word you meant to use, not perpetrating) a misconception.

As I said in my other post, folks have preferences, and I have mine as you yours. Interestingly, what I describe and what I personally prefer, only came after I was exposed to a system that was capable of that level of performance. Until then I really didn't understand what folks meant by 'specific' depth of image comments, I thought it was all about equipment hype by salesmen as I only heard a more 'generalized' sense of depth of image, much as I thought break in being a bunch of hype by salemen and manufacturers.

Now, since you have joined this thread why not share with us your views of how both Blindjim and Tbooose can set up their systems - you will note both have sidewall problems (one speaker near a wall and another near an open space) and at least Tbooose has a backwall issue as well.

BTW, I looked at your system and photos. What a great looking HT system. Looks like you put in a lot of effort. Congratulations...........
I use test CDs to give me an idea of what's going on. For the final details I use listening tests and intuition.
Hi guys,

I thought I might share my experience with my imbalanced room. Hope this might help give some ideas.

My listening room is the standard L-shaped room. Early on I experimented with several setups, playing across the long wall of the foot towards the top of L, playing diagonally across the foot of the L, and lastly playing from the toe of the L towards the heel. Both room aesthetics and best sound response led me to staying with the later arrangement. This left the problem of having the right speaker "see" a side wall and the left speaker "see" a large open space. The effect of this is much as Newbee described. The image was pulled to the right and the only way I could balance the sound level from each speaker was to pull the left speaker much closer toward the listening position.

I'll fast forward to keep this short. What I have found to work very well for me was to use absorbtion along the right hand wall in an attempt to make the right hand speaker "see" little or no reflective surface. As a result, I have not had to use excessive toe-in or different placement of one speaker to the other. That's not to say that I don't still have other room issues to deal with, but the imbalance does not seem to be a problem.

One piece of advice I can offer is to avoid overdamping the room. It is easier to do than most people think. IMO, eliminating all slap echo can be detrimental. I also think, as Newbee posted, that alot can be done just by getting furnishings in first. I'm coming to the realization of this last point because I've stumbled into doing this last. The more upholstered chairs and things I've brought in the more this point is driven home.

Rives is correct that the DIY approach is full of trial and error, but it can also be fun and rewarding if you don't piss of your significant other in the process. I've tried DIY bass traps, DIY absorption and DIY room lenses. All have made an impact on the sound in my room and I do all three of these still, though the lenses tend to come and go. They do make a difference but I'm still accessing their effect since I've changed much of my system.

Best,

Dan
Newbee,

Nevermind - I don't think you grasped what I was trying to say. I mean how did you construe what I say to mean that there is "a definitive or only way of setting up speakers and there is only one possible end result"; frankly, I just can't see how my comments imply this. Anyway, I meant no offence....just my two cents thats all.
Shadorne, I thought I pointed out in my first paragraph what I thought was offensive in your post - your statement that you were going to clear up a "common misconception being perpetrated here", when in fact there was no 'common misconception' being perpetrated and all you really did was to say that in a perfectly symetrical set up the out of phase information appearing to the outside of the speakers did, in essense, not damage or effect the in phase information appearing between the speakers.

I didn't take offense, however I did want to make sure that folks reading all of these threads did not become confused by your statements and to what kinds of systems, and individual sonic goals, they might apply.

I would suggest however, as this has come up in other posts you have made, it is very helpful, and you'll draw far fewer flies, if the content of your post really matches the subject line of your post which you use to draw peoples attention.

FWIW. JMHO.