Is it possible to adapt kt88 to a 6A3 single ended

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

A word to the wise is sufficient.

Charles,you agreed on all his guesses & opinions without any technical bearing.

Rleff,Yes,I did pay attention to those wild guesses.

10-20-15: Charles1dad
A word to the wise is sufficient.

One would think so, Charles, but evidently not in this case.

Realdeal, in addition to the architectural differences I cited between the two tubes, with one being a directly heated triode and the other being an indirectly heated beam power tetrode (sometimes referred to as a beam power pentode), you might examine and compare the numbers in the datasheets for the two tubes. Which I did before posting.

You might consider, for example, the numbers for filament current, transconductance, plate resistance, and typical operating voltages and currents for the plates and grid(s) of each tube, among other numbers. As well as the graphs that will be included in a comprehensive datasheet.

Wild guesses? Yes, I did make a couple. In addition to guessing that the result of the substitution would likely be worse than poor sonics, I optimistically made a wild guess that depending on the design of the specific amplifier the result may very well NOT be smoke and fire.

Good luck.
-- Al