How to tell if Acoustic Treatment is Needed?


I have a 12x22x8.5 ft room with the audio on the long wall - for various reasons - facing the listening chair 8.5' away from front of speakers. The soundstage is excellent with the center clean and tight. The ceiling slopes from 7.5' to 9' upwards from speaker wall to wall behind chair. I have no complaints; I think the sound is very good, although with 60 year-old ears and not a lot of experience with high-end audio systems I don't know whether MY budget system can be better.

I do know that there are furnishings in the room that people say do create problems, such as a large glass-fronted picture behind the chair, a coffee table in front of the chair. The speakers are older Mission 762s with front ports and thin cabinets (similar to Harbeth/Spendor BBC style) which sound quite nice. They sit with their back edge about 20" from wall.

My question is: How can one tell - or, what do you listen for - in order to determine if acoustic treatments would improve the sound? For example, I've tried moving the coffee table away from the chair but couldn't determine a change in sound.
kencalgary
Great suggestions and resources here for treatment. Ken, I'd have to agree that glass behind your head is a big no-no for optimum sound, but again, if it ain't broke...

That said, yes, get rid of the glass and replace it with some sort of diffusion. I put up some heavy curtains and have a project to build a DIY diffusion panel. The OC 703 panels that are mentioned are absorptive panels and NOT diffusion. In addition to the great resource for the inexpensive covered 703 panels, they are also available from companies that deal in insulation (these are Corning insulation panels made from dense foam). A five pack of 2X4 panels should be a bit over $100, or rather they are in my area. These are normally not the foam carried by Home Depot and other large chains. It is also not good to have glass or hard surfaces in between your speakers on the back wall, and here again a combination of diffusion and bass traps may be the way to go. Absorption can also be used, as on the side walls and ceiling. There are numerous threads and resources for room treatment. I would imagine, given that you are happy with the sound now, and by the fact that you are listening nearfield, that you may find that limiting treatment to only one or two points may make a big difference. It is a great suggestion to experiment before jumping in head first by removing the offending glass and replacing it temporarily with a thick foam cushion or heavy blanket if you can find some way to suspend either behind you. Play some music you are very familiar with before and after and see if the difference that makes is worth the effort and expense.

Again, I would not dwell further on it if you cannot hear a difference, and would go with that great old children's song lyric that I remember from Romper Room ...If you're happy and you know it clap your hands! Hey, was that an echo I heard just then?
No Joke. If you don't have them, you need them. There is no room that couldn't benefit from them.
Shadorne is 100% correct. You should move your listening chair away from the back wall. Try getting about 6 feet away from the speakers. So your ears might be 3 feet from the back wall and the front of the speakers 3 feet from that wall. Give that a try and let us know. It is cheaper than room acoustic treatments I believe.
Definitely try alternative placement ideas before you spend $$$ on the problem. If nothing else, it will help optomize what you already have.

Then get some coush cushions or quilts and oth4er dampening things (borrow some from other audiophiles if you can) and try them around the room. In the corners as bass traps and at the 1st reflection points. If you are like me, they will be revelatory, and then there's no going back.

IMO treating a room is almost always necessary and rarely does harm unless it is overdone (or done improperly).

Bob
Shadorne is 100% correct. You should move your listening chair away from the back wall. Try getting about 6 feet away from the speakers. So your ears might be 3 feet from the back wall and the front of the speakers 3 feet from that wall. Give that a try and let us know. It is cheaper than room acoustic treatments I believe.

If you move six feet from your speakers you will also, very likely have to bring the speakers together as well in order to keep the soundstage focused. This, in turn, may also reduce your soundstage and imaging abilities to a smaller space. This is based upon my own experience with various speakers in my own space. I can tell you that in my room of similar proportions, that arrangement also looks pretty ridiculous and closes the room off to a significant degree. You mentioned you have a coffee table which makes this proposition even more challenging. It rates extremely low in the WAF. Hell, I don't even like it, in every way imaginable (visually and acoustically). Diffusion on the back wall is a far more pleasing solution for me. BTW, speaking of the coffee table - you did mention that you'd tried moving it away from the chair. You might try two other things: eliminate the table all together and see what that sounds like. The second is to leave the table in the same place you use it and find the actual reflection points on the table. To do this place a mirror flat on the table surface. Sit in your listening position and move the mirror around the table until you can see the reflection of each speaker in the mirror (two separate spots on the table). As a test, in those spots place a pillow or a small plant or something that my otherwise absorb or diffuse the sound. See if that makes a difference for you.

Keep in mind, that none of this stuff may occur to you to make a difference at all, or perhaps it makes a difference, but one you'd really have to make an effort to hear yourself. There's no doubt the physical changes in the room do make a difference, and that treating a room can have a positive effect. The question really is do you hear it, is it worth it to you, and do you care about the differences it does make. If the answer is no after giving it a try, then keep on enjoying what you have!