Using 6V6's in a 6L6 circuit

[mikepukmel]

HI All,
I found an old thread "Using 6L6's in a 6V6 circuit" where the guy was asking if in a pinch he could use 6L6's in his older...

[AndyM]

So I found this old Traynor rotting away in the corner of my basement; it's got a great sound, but it's impossible to push it into overdrive without bursting...

[meansean]

I just replaced the tube in my Marshall VS100 Comco. Do I need to rebias?