VH4S volume fluctuates on A & B sides

[prsdiezel]

I think there is a problem with my amp, the volume fluctuates on both A & B sides, one more so than the other. There are serious volume swells and drops and sometimes on side B it actually just cuts out completely. The more I played it the worse it got, i was at my friends studio and thought it was the cab. But we tried it through 4 different sets of cabs (2 of which were stereo) but the problem persisted. Does anyone know what the problem is?

 

[Duolos]

When was he last time you retubed? It could be time. It may need to be looked over to be properly diagnosed and fixed. Let me know and I will help.

 

[prsdiezel]

Yeah the tubes are new. I replaced all the JJ preamp tubes (thats what came stock in 2000) and the powertubes are GT El34s. I didn't get it biased though because it had EL34s in it before.

 

[Ventura]

I think it needs biasing... Fact is, pending on how long these tubes have been in it and played on without biasing, they too could be already hooped. Biasing is necessary for ALL tube swaps no matter what. Sad but true (Metallica).

I hope this helps!
V.

 

[prsdiezel]

Yeah I think thats what it is also the bias. Because all of the tubes are lite normal and its doing the same volume swells on all the channels. Plus the last time it was biased it was at the factory in 2000 thanks for the help. I'll try that and see if that helps.