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Lower volume from right channel

About a week ago while playing my custom-made push-pull EL34 amp I noticed a sudden spark coming from the bottom of the amp toward the back. I immediately turned the amp off. A few minutes later I bravely turned the amp back on and surprisingly it continued to play music. However, I've noticed the balance has been off since experiencing this. The left channel appears louder, with greater presence. Can anyone diagnose what the problem could possibly be before I have  a tech look at it. Thanks for your feedback!
a_passion
a_passion OP
20 posts
 
Thanks for your feedback. I will try swapping tubes and let you know the results.
jea48
4,405 posts
 

I would look for a blown EL34 tube screen resistor. Should be easy to see.

http://www.kbapps.com/audio/tubedataspecifications/images/el34_05.gif 

Follow pin 1 on each right channel EL34 tube for the resistor for each tube.

Cause?

Bias is way off.

Tube shorted.

Possibly a bad driver tube.

How many hours do you have on the power tubes? Average life, I believe, is about 2000 hours.

a_passion OP
20 posts
 
I swapped the tubes but found the situation to be the same. I'll have a tech check the above possible causes. Thanks for the feedback gentlemen!
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