Bad tubes??

[kayo_michael]

I am suspecting that one or more of my 12ax7's in the 18w TMB might be bad.

I don't have spares to try, but oday I switched around the tubes and my Normal channel lost alof of volume.
For those of you that haven't seen my issues in the 18watt side of the forum, I've had fizzy overdrive in the TMB ch, while I thought the Normal channel was great.

I'm not very knowledgable on what tube does what, so can anyone help me find which tube might be bad?

Before the swap, my TMB ch was fizzy when cranked and had significantly lower volume compared to the normal ch. Normal ch sounded good and took pedals well.

I basically did a rotation of tubes V1 went around to V3, V3->V2 & V2->V1.
I used the dockery layout where V1 is the guitar input, V2 is the PI, V3 had the 100k resistor.

After the switch both channels lost significant volume and both channels just sound AWFUL.

Any guesses or insight on which tube might be the bad tomato?

[Colin_D]

My guess is that your bad tube is now in the PI. That will affect both channels. With your last configuration whatever was the PI was probably OK, along with the triode that the normal channel uses. Without a tester I don't think there's any real way to say for sure which one it is. I'd just buy a handful of inexpensive preamp tubes for use when debugging and building amps.

[kayo_michael]

i have the 3 EH tubes i got from thetubestore.com and they were $10 ea.
I think I'll go and order a few more and swap them in.

Thanks Colin.