Pentode Power Tubes - Ultralinear vs Triode


While I’ve seen a bunch of posts on power tube rolling, I haven’t seen much mention of how preferences correlate to what mode you run if your amp has that option. I have a Primaluna DPHP that has the Ultralinear/Triode mode remote and can run a bunch of EL34 variants up to KT150.
So far I’ve only tried the stock EL34 and Tung-Sol 7581A and seem to prefer Triode mode with both. Before coughing up for another set of 8 to try I’m doing more research. I think based on my preferences so far that the bigger, punchier tubes may not be the way for me to go. I could be destined to find my way into SET amps eventually.

So which tubes do you prefer in what mode of operation?
cat_doorman

Showing 1 response by tablejockey

DPHP user here.

Check out the KT77 is you like the EL34 sound. To my ears they are a little more dynamic overall. Look at KT88 for more on the bottom end at the expense of less midrange magic.

 I have been using the old RCA 6l6G coke bottle in my PL. They are a lower power(different from modern 6L6). They are a close enough combination of EL34 mid and KT88 dynamics.
One of the few NOS American power tubes still available for a reasonable cost.
https://www.ebay.com/itm/RCA-6L6G-Smoked-Glass-Tube-NOS-foil-twin-D-getter-copper-grid-posts-code-35...
They have a "dry"sound which to me is more convincing compared to the "lush" EL34 tone.

I prefer the triode setting most listening sessions. A flat recording sometimes sounds better in UL. You are aware of the 2 innermost preamp gain tube also will fine tune the sound? Subtle, but another tweaky option.

Be an early adopter and try the KT170
https://primalunablog.com/2020/10/30/tung-sol-kt170/
They should be like a supercharged KT150, which already is a powerful tube. I haven't tried them in my amp yet. 8=$$$$