Mix 'n match power tubes

[greiswig]

So I recently started to get hum in my KT88-powered D'Lite. I had previously biased the tubes to 48ma each, but now one of them had drifted high...pulling 65ma. That explained the hum.

So, assuming that one of the tubes is failing in some way, I start to wonder: I have a 6550 that also had its mate fail. What if, by some happy coincidence, the two remaining widows could be put together? If they both biased similarly, would there be any harm in trying out a KT88/6550 pairing in a two-hole amp?

Thanks!

[John_P_WI]

Yes it can be done and sounds very cool. I have done it on plexi's and 2204's in the past to warm them up, not a D style as in your case. I used 6L6's and 6V6's and it gives a great blues vibe.

Individual bias pots plus the ability to run the tubes in "triode" helps. The harmonic content is increased greatly. All is good...

John