Have you tried one?or just a wild guess.
I would never try any such substitution, for fear of damaging the amplifier, including the possibilities of damaging both its output transformers and its power transformer.
A 6A3 is a very low power 4-pin directly heated triode. It has 3 elements -- a filament/cathode, a control grid, and a plate.
A KT88 is a much higher powered indirectly heated beam power tube. It has 8 pins, providing connections to a filament, a separate cathode, a control grid, a screen grid, beam forming elements, and a plate.
The two tubes have numerous electrical parameters that are highly dissimilar. There are so many differences that I would see no point in taking the time to analyze their consequences. And in any event a schematic and other design information for the specific amplifier being used would be necessary to properly do so.
IMO substituting a KT88 for a 6A3 would at best, if you're very lucky, result in poor sonics. At worst it would result in smoke and fire. My guess is that the result would be somewhere in between, probably a damaged amp.
Rleff, thanks :-)
Regards,
-- Al
