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August 5, 2008 - 6:33pm
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Channel Imbalance - HELP
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Two words for you:
Room acoustics
Is one speaker a lot closer to walls than the other?
I originally thought this (and maybe my hearing too), but no.
1: The room has changed several times too
2: The speakers are currently equidistant from the side and rear walls
3: I have tested with an SPL metre right up at the speaker (1cm from transducer) so room acoustics should have no effect.
Measure the left/right output with a volt/ohm meter and a test tone. I bet they come out identical. Could be caused by an absorptive piece of furniture being off center or a door way, but I'd bet it's somehow related to room acoustics. It's the only reasonable explanation. You could use the preamp's balance control to correct it. That's more treating the symptom than the cause but most people other than me would be happy with that solution. I'm a little OCD (obsessive compulsive disorder) when it comes to audio. How about a diagram of the room?
I also vote from room acoustics.
One trick that I find can work is to add toe-in to the speaker that seems recessed in volume (or toe-out the louder of the two).
This change in dispersion pattern can line things up nicely.
Also do not hesitate to move the softer speaker closer and otherwise move the speakers around. While measurements are a great place to start, final placement must be done by ear.
What about windows, drapes, of absorbant furniture like couches. Do you have an open door near the weak side?
Great points Elk. Also keep in mind if the speakers aren't equidistant from the listening position this can ruin the illusion of imaging 2 inches can make a big difference. Once while cleaning my college roommate moved my speakers to clean, then moved them back. Visually I didn't notice but the imaging just wasn't right and it drove me nuts all night. The next day my roommate came home as I was measuring things and I "confronted*" him about his sabotage disguised as housekeeping. He fessed up and after all of the measurements were done one speaker was 3 inches off center. After that he was in awe of my listening abilities and never again dared to move my speakers.
My Martin Logan's are dialed in to less than a 1/4" of an inch, God help anyone who breaths heavily on them! I'm sick I know. There really is no turning back for me.
*In a good-natured kidding way.
Thanks for the posts so far, but it's definitely not room acoustics for these reasons:
1: It has been like this in three different rooms.
2: I have measured using an SPL metre about 1cm from the speaker surface.
3: I also run a second set of I/Cs from the preamp which drives a Behringer DSP1124P (which drives my sub). The level lights on the 1124P indicate a higher level in the left channel also!
ARRGH!
Is your source defective? Bad wiring or of different lengths?
Truly odd.
I just re-read your first post.
If you have a way of wiring things up so that the balance is OK, why not just leave it that way?
Question: do you have two pairs of preamp outs or are you splitting it? If splitting, perhaps there is something wrong with one of the splitters.
Ok, definitely going to have to start doing a few more measurements. Thanks for the replies so far. I was hoping someone else would have experienced something like this - we've got close, but nothing exactly the same.
So strange!
Consider me curios and baffled. Let us know if you figure it out