Room Acoustics Problem????


I'm hoping someone can provide some input to resolve what I "think" is a room acoustics problem. I have a HT setup in a rectangular shaped room approximately 20' (L) by 12' (W). My television and front speakers are located on the length of the room. Although I have 5 speakers in the room for surround HT sound, I listen a great deal to 2 channel as well. What I'm noticing is that the left speaker always appears to be louder than the right speaker, throwing the sound off-balance. After reading a few articles on room acoustics, I'm attributing the louder sound to the bay windows which are located next to the left speaker. I'm assuming the bay windows add increased reflections in the sound. The right speaker is located next to an open space so there is no added reflections from that speaker.

Is there an easy way of fixing this problem other than using the balance control to change the output? Would adding absorption materials near the bay windows (maybe curtains?) solve the problem? I'm hoping that I could come up with a simple solution without spending too much money. Any advice would be appreciated!

Tony
calgarian5355
If you are up to it get a copy of CARA - I bought it and as markvetnz put it - CARA usually recommends a set up that is not Symmetrical.

It takes a lot of measuring and input, but it picks placements that I would have never figured out using just my ears. I don't have the best ears or patience, but itÂ’s a suggestion anyway.

Rob
One of the biggest mistakes people make is to assume that speakers have to be set up symmetrically! This is not true. I have a similar sort of room to yours and the sound always seemed to be more prominent on the right. By working tirelessly on the speaker placement I got it sorted beautifully by moving the right speaker back in 1/2' increments. The speakers now image perfectly at all frequencies. In my opinion you should try all different permutations of speaker positions possible. Get a test CD to sort the imaging out.
Someone who is very knowledgeable is Ethan Winer of Realtraps. Give him a call. Pics would probably help too. He's very helpful with people that aren't even interested in buying anything. His prices though are the best for what you get from what I've seen. Windows are bad and thick heavy curtains would definitely help. If you have a balance control don't be afraid to use it, although I understand your thoughts there. Heavy drapes should be your next step if possible. DSP like a Tact will also work but is obviously more expensive. When room acoustics get better so does the sound quality.
I had the same exact problem and I am lucky to have adjustments on dpeaker to compensate for the room, when I first moved into new house, I got a more powerful amp and thought it might be the amp, but it was the room and the adjustment worked great.

P.S. toe-in and one speaker a few extra inches out works great too
Couple more links: ASC, Acoustic Sciences Corp, maker of the famous tube trap, acousticsciences.com, and Rives Audio, rivesaudio.com a very interesting site. Don't forget the ceiling! Anybody have any thoughts on ceiling treatments?
If you live in a big city you might be able to find a place that sells second hand hotel curtains, the better ones are what they call blackout curtians they absorb light + sound. but it is not a wall,you can make an absorbing panell on a stand and move it in place for critical listening, if you want to go cheap even a used office divider will help.
Use the balance control, you might be surprised! Any added distortion, if you can hear it, surely is less than the "distortion" that you are experiencing now.
With your unbalanced room/speaker placement, there will always be some unsatisfactory element to the sound.
In fact, another solution, would be to equalize the sound from the speaker with the two boundaries, but gosh that might introduce some other "detectable" distortion, which, again, might be worse than what you have.
Another more acceptable way (at least to the cable crowd)to equalize for one channel, is to get a different speaker wire for that channel.
Salut, Bob P.
Thanks for your responses. Currently, I have my speakers toed in slightly. According to an article I read from a link posted on this site, I toed the speakers inward, pointing towards an imaginary spot 5' behind the listening position (ie...assuming the two speakers and the "listening position" form an equilateral triangle, the speakers are toed in to a point 5' behind the listening postion). As one of you suggested, I tried toeing in the left speaker more than the other, but this only resulted in a rather confusing soundstage. I'll try moving the right speaker forward a couple inches to see if that makes a difference.

You are correct in assuming that the lack of reflections from the right speaker are contributing as well to the decreased volume from that particular speaker. Unfortunately, it's impossible for me to close off that space or to add a hard wall divider (I technically could do it..but it would really look stupid!). I suppose I'll try hanging up some temporary curtains to see if that helps the problem; real curtains can easily cost more than a new audio component though!

I've never heard of "echobusters" before. I'll try doing some research to see if that might help me.

As a very last resort, I'll use that nasty balance control to try to solve the problem, although I really don't like the idea of doing so!

By the way, my speakers are set up approximately 16" from the back wall...and my left speaker is about 2' from the side wall. My speakers are rear ported so placing them any closer to the back wall creates a boomy/muddy bass response. The speaker placement is based on the location of my wall mounted television. The right speaker, as I mentioned earlier, is not located next to a side wall (just an open space/hallway leading to my dining room).

Tony
how far are the speakers from the side and back wall? In that room they should be about 5" apart and 3-4" away from the back wall you should be sitting about 4' off the back wall.
I have experienced the exact same problem as you in pretty much the same size room! A number of fixes for me. First, I discovered that one speaker was about 2db louder (near cone measurement), I replaced some tubes to equalize output. Second, speaker placement, front to back, side to side, and amount of toe in all effect this to some extent. Third, room treatments can make a large difference as well, something like an echobuster at your first reflection point on your wall should help (curtains may help some as well).
Goinbroke makes an interesting observation in that it as much the lack of reinforcement on the speaker in the open area that is part of the problem. Some sort of free standing combination absorber/reflector at first reflection point might help. I plan on experimenting with this as well. In the meantime there are times when I still have to use the balance control.
I forgot to mention another possibility. If volume is a problem, you can alter the balance by moving the right speaker forward a few inches, or the left backward a few inches, 'til you get a tightly focused center image. Also, be sure to use a mono source to determine when you have a truely centered image. Its much easier to do and more accurate than using a stereo source.
Goinbroke explained the issue that I have experienced in my own room. I hate to use the balance function, but sometimes it's better than tipping my head to try to make up for the 'suck out' I get from a stairwell and a door. Does closing the door help?
My guess is that the real culprit is the opposite of what you suggest. Am I correct in understanding you to mean that there's an opening or doorway in the wall by the right speaker? If this is the case, it's that hole that is most likely causing the apparent difference in volume. In other words, it's not that the left speaker is louder, but that the right one is quieter due to no first reflection, at all. While the windows will result in an increase in reflected high frequency energy, this usually makes that speaker seem too bright, as opposed to too loud, as the apparent tonal balance of that speaker appears to get shifted. In any case, the fix is still the same since closing that opening in the wall is probably not an option. Try what Newbee suggested (toe-in) and what you suggested (curtains), as well. Don't be afraid to use the balance control a little, either, to get it just right. That's what it's there for and it shouldn't hurt the sound quality since it is already in the circuit anyway (unless it's defeatable). Hope that helps.
Have you tried toeing in your speakers substantially - this can reduce the 1st reflections enormously. If the high frequencies become too hot try crossing the axis in front of your listening position.