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Left / Right Maddening Problem

Hello all,

I have a conventional 5.1 HT / music system: DVD, CD, Pre-Pro, front amp, 3-channel amp for surround and center and self-powered sub.

For a test CD, I use the Stereophile Test CD 002-2, which provides a dog barking to verify left and right channels, a bark that should come from between the two front speakers and an out-of-phase dog bark.

Both the CD and the DVD (with the center and rear channels turned off) exhibit the same anomaly: the left dog emanates from the right speaker, while the left dog comes from the center. Neither is distorted. The center dog bark is perfectly placed and undistorted. The out of phase dog is indistinctly located and somewhat muffled - which is the expected behavior.

Since the CD and DVD are connected to the pre/pro at separate inputs, I think I can rule out the units themselves as being at fault.

I changed the front amp and got the same result. I changed the pre/pro and got the same result. I changed the connecting cables from the CD and the DVD, which also made no difference.

I deliberately reversed the power and ground on one front speaker, which did not help.

Also, I ran the test setup from the pre/pro to make sure that left and right speakers are correctly connected and identified by location.

Lastly, I played the test CD on a boombox to be sure that it does, in fact, produce the dog barking from the left and right side speakers - which it does.

So, now I am unashamedly stumped and am appealing to you all for help. (My wife would also appreciate a resolution to this issue since my testing is making her nuts.)

Any and all suggestions will be welcomed.

Thanks.

Jon
opteron05
tobias
1,534 posts
 
Another last ditch suggestion: look into speaker placement and room effects. Is your room symmetrical, for example? My rear wall has a 12-inch step on the left side and when my speakers are not precisely toed in the image shifts to the left.

My reference on this subject is Jim Smith's Get Better Sound.

http://www.getbettersound.com/
commcat
79 posts
 
How would a Test CD designed specifically for 2-channel audio correctly operate in a 5.1 channel home theater system? With a 3-channel amplifier how would the audio input channels be separated and distributed if there are only 2 to begin with? The Test CD works correctly with a 2 channel amplifier (the boombox) but not with a Home Theater processor/amplifier. Have you tried using a Test CD designed for 5.1 HT?
opteron05 OP
16 posts
 
Thanks, Puerto.

Puerto: I can certainly try duping the CD, however, if I make a truly accurate copy, I would expect it to perform just as the original has. I will give it a try and let you know what happens.

Jon
opteron05 OP
16 posts
 
Thanks, Tobias.

This is a provocative approach. I have tried to keep things as symmetrical as possible (the room is 10 x 18 with curtained windows along one long wall and seating along the short wall). Ordinarily, I wouldn't expect the bit of difference to cause as much imbalance as I am getting, but this is worthwhile trying as well. I'll get back to you.

Jon
opteron05 OP
16 posts
 
Commcat,

In the interest of brevity, I left out some detail that might have misled you. My pre/pro is an NAD T-163. This unit specifically allows the user to select the kind of processing to apply to each input. As such, I have Stereo enabled on the CD input, and Dolby II enabled for the DVD.

So, my expectation of 2 channel performance for the test CD is the same as it is for any other CD - namely, just as if I was using a complete 2 channel setup.

Where the DVD is concerned, the Dolby processing of the audio might make a difference in what I hear, but the source material is not Dolby encoded. As such, with the rear and center channels "dead", if the problem was with the CD player, I would expect there to be a significant difference, with the DVD conforming far closer to my expectations. That it produces an identical location of the dog barking as does the CD player makes me think that the problem lies elsewhere... I hope this is clear.

Jon
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