Tung Sol KT 170

Wow!  This is new to me.  FWIW I traded my cj ARTsa, which used (8) KT 120 for a new cj ART150 which uses (4) KT 150 and the new one offers a worthwhile improvement in every respect.  It is more stable, too.  In fact in over a year of daily use I have only had to re-adjust the bias on one tube and it by only a small amount.  It does put out a lot of heat and for that reason I put cooling fans on it.  In any event, based on this experience I would guess that the KT 170 has the potential to offer additional performance benefits for amps designed to use them.

I looked again at the spec sheet that was linked. What's up with all of the redacting??

My little Dennis Had Firebottle amp can use pretty most any power tube (except 300bs and a few others), although I'd possibly send him an email before trying 170s. He did tell me once (email) that 150s worked great in my amp, and they did.

Just ordered 4 for my Qualiton X200 that will work with out modification.