Ch1 on Crunch Noise.

[pvdmac]

Just got my new Mk V25...love it...BUT...
Ch1 on Clean is silent...great.
Ch1 on Fat is silent...great.
Ch1 on Crunch....HUM....not great.

Ch2 on IIC...not so silent....OK
Ch2 on IV...not so silent...OK
Ch2 on Extreme...not so silent...OK

The only one I have A problem with is Ch1 on Crunch...huge jump in background hum...think it's a preamp tube...any advise on which one it might be.
I'm not too clued up on valve amps...so any advice would be greatly appreciated.

Cheers Guys.

 

[jb's 52]

I don't have the Mark V25, but there should be a tube chart in the manual
that can help determine which tube(s) to start rolling out.

 

[Monstercastle]

V1b, V2a, V3a are all used in Crunch mode. The tube chart in the manual (downloadable) calls it out. Cross reference the tubes/triodes with those working properly and you should find the culprit. Assuming it's a tube.