Tube Amp settings: Triode vs UL; 8 ohm vs. 4 ohm ?

A lot of people prefer triode operation over ultralinear for sound quality (smoother, less brittle sound), but the cost is lower output.  I have only heard a few amps where such a switch can be made for a direct comparison and I don’t recall liking triode operation that much more than ultralinear.  Again, give both a try.

(On a different amp) I was expecting to like triode better the UL, but that was not the case as the bass was thin. But the vocal were more airy in a nice way using UL.
(the beauty of a switch is it is easy to try it.)

Maybe another amp driving the woofers would be a thing for me to try.

The only process is to 'try and see'.

I once had 6 ohm, 88db speaker with an impedance dip down to 3 ohms. Naturally I kept the amp on UL mode because that sounded better on most music and hooked the speakers up to the 4 ohm taps.

It sounded great! Listened to it for more than a year like this before trying the 8 ohm taps for kicks.

Well, the mid and upper band frequencies had more 'air'...and no discernable change in bass response.

Who would have thought. I wasted a year listening to the 4 ohm taps.

UL and 8 ohm.

Save yourself the aggravation.

UL and 8 ohm.

Save yourself the aggravation.

Simply not true. There is no way this is a universal decision. You have to take time and actually listen to all of the various setting options.

Charles

Not usually a huge deal either way. I have Rogue Apollo with the triode/UL switch, and it still sounds like mostly the same amp in either mode. Different amps sound different by a lot - these 2 modes sound different by a little. Triode is a little smoother cleaner in the midrange. UL has a little more dynamics and slam. These amps being 250 Watts / UL (150 Triode?) and my speakers 96dB means the power loss in triode isn’t very meaningful in my case. For a long time I’ve preferred UL, but that might be changing as I age lol. Tone is the same either way - a tube roll effects more change, especially in tone.

Likewise, the 4 and 8 ohm taps both sound good, and it sounds like the same amp either way. I haven’t spent much time trying to parse out the nuances here, but I've run the Apollo amps a lot from either tap over the years. You’ll usually sacrifice some power by mismatching the tap to your speaker, and the distortion can go either higher OR lower, depending on the amp. For example, the Rogue M180 was measured by Stereophile with lower distortion (at below peak levels) from 4 ohms tap into 8 ohms, than it was from 8 ohms tap into 8 ohms. They also measured the Triode vs. UL modes, and some distortions are a little lower and others a little higher in each mode - which matches my listening. It just effects some minor trade-offs but is still the same amp.