Help! Noisy Herbie!

[Me]

Hello!

My Herbie seems to have got rather noisy. Unusually it seems to be noisy on channel 1 clean, but not noticeable on 2 or 3 (which I'd have guessed the higher gain to have made any noises worse!

Any clues?

 

[Bato]

Get some fresh tubes.

 

[Me]

Get some fresh tubes.

That's what I figured, but would rather swap out one or 2, than blow my entire christmas budget on tubes. I've already spent half of it I shouldn't on guitar related equipment (hello 2nd hand Parker MIDIfly, and new Voodoo Lab Pedal Switcher)!

Is it likely to be a particular one?