llllllllllllllllllllllll wrote:what kind of modifications would have to be done, if any, to use these tubes. is this sort of thing best left for a tech?
The first thing that comes to mind is the heater current draw. 6L6GC's draw 0.9A of heater current per tube. 6550's draw 1.6A each, as do KT88's. So right there, you're talking about a 78% increase in the heater current draw, which in some amps you might be fine with, and in other amps, you might blow the heater tap on your power transformer.
The thing is, EL34's are also 1.6A per heater, so in this respect (heater current draw) amps that use EL34's can use 6550's can use KT88's and vice-versa. Likewise, amps that use EL34's can use 6L6's. But not all amps that run 6L6's can use EL34's, 6550's, or KT88's.
Blowing your power transformer is totally not fun. Nor is it cheap. Even if you can put in a new PT by yourself, you're still talking about a good chunk of change (about $100, give or take $50) and a bunch of time to find the right one, order it, get it, take out the old one, put in the new one, etc etc.
