Tube Amp Problem - Help!

L

lodidodi

New member
Hello! I have a Marshall EL84 20/20 stereo power amp. I use it with two reactive loadboxes to record it direct in my DAW.
I just bought this amp from someone and when i plugged both channels in stereo into my interface to record, i noticed one channel has a slightly lower volume and it sounds quite different.
I use the amp exclusively for a crunch tone that i get from a Marshall JMP-1 valve preamp.
The affected channel has a different distortion tone which is less pleasant for me, seems more weak and not so tight compared to the other channel of the power amp, apart from the slightly less signal it outputs.
What could be the problem?
I am tube amp noob. Is this a tubing needing replacement or some other thing? thank you in advance for any response!
 
Re: Tube Amp Problem - Help!

With different distortion and lower volume that sounds like a tube problem. Check the bias for both sides first (shouldn't cost much if you take it to a tech for biasing). If the biasing doesn't fix the problem, get a new matched set for the amp, bias again, and see if that does it.
 
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Re: Tube Amp Problem - Help!

9/10, tubes are the issue. If it were me, I’d probably get some new, matched power tubes and replace and bias them. Then see where you are at.
 
Re: Tube Amp Problem - Help!

The Marshall 20/20 is well-known for its overheating and power issues. Get yourself an old Johnson J Station and be done with it.
 
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