Ultralinear vs. Triode

I have a pair of VAC PA160 mkII monoblocks. They can be run in triode, ultralinear and pentode, feedback is also adjustable. Running el-34's in triode with no feedback yielded the sweetest mid's, but was lacking in dynamic punch. Running the el-34's in ultralinear pushed them a little out of control (flabby bass). For greatest dynamics and personal statisfaction, I've been running kt-88's in ultralinear with a little feedback. Etched detail in the midrange with low end slam. Lots of top end energy. Couldn't be happier.

To me Triode means EL34s tubes. Even amongst el34 brands there is a sonic difference.My CJ 5's aren't user switchable.What you describe sounds like the sound from a Mesa Barron.My dealer kept trying to push me into one.I had one for a home trial;two times. To me this (MB) isn't very good at either (Ul,-or Tr)-- Never heard your amp-- I'm just using your description; and how "that" compares to the Messa.Circuitry is first;then tubes second.

My one experience auditioning with a switchable amp was Air Tight 100w monoblocks with EL-34's through SoundLab Dynastats (electrostat mid/upper panels, dynamic cone in reflex box bass). I thought that the amps were much more in control and much higher in fidelity, particularly at the low and high ends and in dynamics and speed, when run in regular mode as opposed to triode (as did the system's owner). I do not know, however, whether their regular operation was ultralinear-wired or not. My own amp is a c-j MV-55, which is wired as standard in ultralinear with EL-34's. In discussing the available triode-wired option with c-j, they basically cautioned against it, informing me that many customers who go this way ultimately are not satisfied, and wind up havig their amp(s) converted back to standard operation. Since there are many highly regarded non-single-ended triode amps made, including ones like CAT that do not employ true triode tubes, one might suppose that this circuit may be more successful in a dedicated design than one with a switch option.

I have Magnum 120's and went for months listening in ultralinear mode but did not like the thin mids/highs, even though it had a nice airy quality and the bass was good as well. I recently put them in triode mode and prefer it. The sound is a little closed down but seems to have more weight and punch. In general it seems more robust and piano has more of the vibrant quality I associate with live music.

my system is:
99 Magnum
Rega 2000 CD
Nordost Blue Heaven (IC and wire)
Magnepan 1.6QR

I agree ultralinear mode sounds very nice in general and with the right system could be the preferred mode, maybe my Maggies are just too bright. I have also recently put Mullard cv4004 tubes in my power amps and tried it both modes, they are richer but seemed to blur the sound a little. I arrive at the same conclusions with these tubes as well.