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Lower gain in left channel.

I just noticed last night that the volume from my left speaker is lower than my right speaker. It is enough that images are pulled towards the right speaker, but it is not glaring. Could this be a sympton of a power tube going bad? I'm running An Air Tight Preamp (with 6 month old new tubes) and a c-j Premiere 11A. I'm not sure the age of any of the tubes of the c-j, I bought it used and have had it for about 1 1/2 years. Would a tube or tubes going bad manifest in this way. There are no strange noises or anything coming from the left channel, just the slightly lowered gain. Thanks for your help.
128x128jond
avguygeorge
2,300 posts
 
Could be the tubes. Make sure all the other connections are tight. If the amp has auto biasing or some other user method you might change tubes--side to side (left with the right)--Driver tubes as well;see if the problem stays on the left. If it stays on the left--change side to side--the tubes in the pre amp.
phild
603 posts
 
Does it happen at all volume levels, or is it only noticeable at very soft levels?? If it only happens at low levels, it could just be the natural effect of the volume control not being able to match precisely...that's natural and it happens with many stereo volume controls. If it happens at all level, then follow the above suggestion and swap tubes side to side. They may not have been a matched pair, one may be older, etc.
jond's avatar
jond OP
5,687 posts
 
It happens at all volumes, so I'll experiment with the tubes.
garfish
1,840 posts
 
Jond; I've had the problem you describe for years, and it's why I always use a pre-amp with channel balance control. My left channel output volume is higher than the right channel, so I always have to dial in about 3-5 dB (biased to the right) of volume to achieve good channel balance and proper imaging. I CAN get good imaging by slightly biasing my listening position-- which is then slightly off center.

I've blamed my room, my speaker set-up, my hearing etc, but in 4-5 years in my present room have yet to figure out why this is the case. I've also changed tubes in my pre-amp several times and it has made no difference. Sorry I can't help. I'll follow this thread with interest. Craig
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