KT-77 vs. KT-66

@tablejockey 

Thanks. Mike Sanders at Quicksilver has told me directly that 6L6 and EL34 cannot be used on my Mono 60 amps.

Thanks for the replies. I realize how much variance can come from amp, manufacturer, etc. and so trying it is the only way.

One thing which patterns these responses that helps me is that the KT66 is definitely going to differ a lot from KT-88's. That's the kind of nudge which helps me move ahead to try it.

@trivema My amp will *not* play a 6L6 so I don't know what it sounds like. 

@noromance I think Bizarro World has a character named Kinkless Friedman to balance out our own.

What do the KT88s sound like?

@jimmy2615 The GL KT-88’s in my system have "slam" and bass response; lower mids have punch. Mids and highs are a bit harsh; this can be tamed a bit with changes in my preamp 6SN7 tube.

Curious how others might answer your question.

@wolf_garcia Thanks for weighing in. I love the KT77's so much I have two pair. I'm very curious if you hear any real difference with the KT66's because they've gotten kind of expensive and hard to find. The GL's are very very hard to find. JJ is more gettable.

@wolf_garcia Thanks for the additional info. I need 4 tubes in my QS monos. I also have the Pass XA25, which is a fine fallback if I have a tube go out.

@jond I'll double check my email. My memory is likely at fault! Thanks for pushing back on my claim -- if I am wrong it will open up some options.

Found my old emails.

Mike Sanders said about my (later) Mono 60's

"They should be able to use KT66 or 6L6 tubes.
The Sixty watt amps have a plate voltage of 500 volts."

He also said,

"EL34s and 6CA7s should not be used in the Sixty watt amp."

So, that's the word from the maker regarding my amps.

I think it's a plate voltage thing. I'm not an engineer and just follow instructions!

Thanks to all for weighing in. Good points, and I learned a lot!