If KF was building an amp today, what tubes would he use?

[Guy G]

What new production tubes do you think fit best in a wreck?

[hairyandy]

I've had decent luck with JJ's, both their EL34 and newer KT77's. Their 12AX7's sound pretty good as well. I really want to try the SED (Svetlana) Winged "C" EL34's though...

Andy

[dartanion]

The SED EL34s sound really nice. Make sure you get those as the Svetlana labeled tubes are now Sovteks. Not that the Sovteks are horrible, they just aren't real SEDs.

A great sounding tube from Sovtek is their new Tung Sol 12AX7s. Another tube from them that Ken would have like is the 6CA7EH as this is a copy of the Seimens 6CA7.

[Robert]

I know you requested new production. I used JJ 12ax7's for several years and recently decided to try NOS tubes. I believe Ken's favorite tube was a Tungsram. I purchased both a NOS Tungsram and Telefunken and placed them in the amp one at a time. Tungsram in V1 was an immediate difference and great improvement in tone and touch. Very transparent, sweet and lively with a richer harmonic content to the tone. Telefunken was the same in V3. Eventhough I paid $50 each it was very well worth it. NOS should last much longer (10,000+ hours) than new production. They also eliminated the annoying idle hiss in the background when not being played.

I'll never go back to new production, it really makes that much difference and especially in a Trainwreck Express.

Just noticed your title question, which is a better question. Short answer would be NOS Tungsram.

[VacuumVoodoo]

I have a feeling KF wouldn't be a stranger to 7591 from EH.

[klingo]

+1 for tungsol 12ax7, i also have a very good sounding JJ ECC803...

2x7591 cathode biaised in a liverpool style amp...

which 7591 do you prefer? EH or JJ?

[VacuumVoodoo]

+1 for tungsol 12ax7, i also have a very good sounding JJ ECC803...

2x7591 cathode biaised in a liverpool style amp...

which 7591 do you prefer? EH or JJ?

Since NOS 7591 are very rare and expensive I have to rely on new production. I tried a batch of JJ and was really disappointed: they didn't deliver the power, drifted in bias after warm up. I went to the trouble of taking full measurements and drawing characteristics - they don't look like original 7591 curves but more like sort of scaled up 6V6GT.
EH 7591 on the other hand perform as specified to the dot. And they deliver both power and punch. I run them at 475-500V plate and pull 45W output power before clipping. (fixed bias)

Yes, 7591 PP cathode bias could interesting, a quick calculation tells me it might be something like EL84 on steroids putting out around 22W in real class A. And pretty early break-up. Need to do some more math on this...