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.

I also have about 200 hours on the M120 Magnums. They are just wonderful. My speakers seem to like more power, so I think I'll be happy with UL for a while. I a few weeks when they're fully run in I'll flow it over to Triode. If you'd like to talk more about some specifics please feel free to email me and we could trade notes.
Eric

I think the above posts tell all; it depends on your speakers sensitivity and impedence.

Since running the amp in triode reduces the wattage by 50%, most of what you are hearing is a result of decreased power. And since we're talking about sound quality and not watts per dollar, a much more fair comparison would be to compare triode mode that has the same wattage as the ultralinear mode.

I tried a Rogue 88 in both triode and ultralinear on some very efficient and high impedence speakers (97db, 14ohm- 30 or 60 watts do not make a difference) and it was no contest as the triode mode beat up the ultralinear mode in all areas. To be sure, if I were using "normal" speakers with 8 ohms and 88db sensitivity my findings would be completely different.

Hi killerpiglet, I posted this on AA too, but since you're here as well....
I think the key thing is the type of music you listen to and what you want to get out of it. I have a Mesa Baron (although I'm not using it now). It can switch from full triode @55 watts to full pentode @150 watts, with stops at 1/3 triode and 2/3 triode. Over Christmas, my best friend, who is a professional guitar player, came over. He has formal training in classical and jazz as well as 'rock', and currenlty performs solo acoustic "new age" instrumentals. He's seen LOTS of the great guitar players live, in clubs and theaters, not stadiums. I have live CD's of many of these guitarists. As soon as I dialed in any triode at all, he said "That's NOT their live sound". Full pentode was it, even for his own CD, which was all acoustic guitar (I really thought he'd pick triode for that one). Full pentode in the Baron is a very aggressive and in your face sound with lots of 'slam'. For rock (using the term loosely) that's what you want. For an acoustic jazz trio, probably not.
I don't think that it's JUST a power difference. The Baron in 2/3 triode still puts out 120 watts I think, and that didn't cut it for the 'live sound'.

I just switched my new Magnum M120's to triode and I immediately missed the power of UL... Yes triode is a little smoother, but the bass slam and imaging gets a little sloppy.

Agreed, it is not a power difference,. It is noticeable at low volumes. I was not running out of power in triode. It simply sounded like a wet noodle. Talk about no PRAT? That's waht it was. And not just for rock.

KP

I just listened to my Rogue Tempest II in triode last week for the 1st time. Not sure if I liked it over Ultralinear. In some ways it sounded better but the dynamics and slam were not there and the soundstage was set futher back. I think UL is overall much more of an accurate live sound.

Usually I like Ultralinear mode better than triode in the VTL and CJ amps. I now own the VAC PHI 300.1 monos and like it much better in triode.

I seriously prefer triode setting (~40W) for rogue tempest magnum integrated. My speakers are Merlin TSM-MM. Triode results more realistic sound IMO.