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Puzzling preamp problem

On some, but not all sources (CDs, records) the right channel of my system seems to overpower the left. This mainly happens in orchestral music.
What’s  puzzling is that most sources usually sound balanced between the two channels. When there is a singer or soloist the sound comes from the center. But when loud instruments (brass mainly) are in the right channel, the left channel seems to migrate to the center.
But when there’s a particular designated voice or instrument in the left channel, it’s very audible in the left speaker.  Very puzzling!
I assume it’s a preamp problem. I have a vintage Conrad-Johnson PV 11 preamp.
The situation has arisen with a variety of amplifiers so I don’t think the problem is there.
Has anyone else experienced this phenomenon?
I guess I’ll have to break down and get the preamp looked at.
128x128rvpiano
rvpiano's avatar
rvpiano OP
2,465 posts
 
It just seems if the right channel is very strong, it wipes out the left.
newbee
4,751 posts
 
When you reversed channels I suspect all you did was reverse the source output, not the pre-amps out put. Swapping the tubes would be more revealing I think.
ricwa
23 posts
 
Could this be normal? I listen to a lot orchestra and experience this phenomena all the time. With an orchestra arrangement, the 1st and 2nd violinist sit up front and to the left of center (stage right) and thus are often louder. When there is a soloist, the soloist is typically front and center or just to the right of center.  
twoleftears's avatar
twoleftears
5,313 posts
 
Swop the cables over connecting the pre- to your monoblocks.  What happens then?
rvpiano's avatar
rvpiano OP
2,465 posts
 
I’ll try swapping the cables and see what happens.
Swapping the tubes is more of a hassle because I have to remove all the tiny screws from the chassis and remove the cover, but it’s worth a try


Interestingly though,  I had a several hour listening session with a friend today, and after everything was warmed up, the problem disappeared and everything sounded great.
So It appears to be a warmup problem, which leads me to suspect the anomaly is caused by the preamp, perhaps a weak tube.

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