Changing Tube Type in an Amp

[Cygnus X1]

Fail, on my part.
I was going under the assumption that it was designed for lower powered tubes.
Old Marshalls, for example, have a bad habit of smoking out transformers when living on the edge.

Swap them, bias them, and have fun!

[Shawn Lutz]

its resistors that needed to be changed/added not the transformer.
btw...6550's in Marshalls rulez!!!!!!!!

[DonP]

During the 80s, US bound Marshalls came with 6550s. Just tubes and resistors were swapped. Reason was that EL34's were unreliable at the time and failed to make the journey overseas. 6550's are heavy duty millitary spec tubes.

[charvel750]

Bob at Eurotubes said that with the properly selected 6550/KT88 you can have enough range on the bias pot to retrofit these into an EL34 head, no problem, no other adjustments...