I hate to say it, but now I think maybe I like my amp in ultralinear mode versus triode

Don’t feel bad about it. There’s some paranormal audiophile force that makes us feel like the more "purist" approach must always be better: triode versus pentode, DHT versus separate heaters, single-ended versus push-pull, ladder-dac versus delta-sigma, discrete circuitry versus opamp / IC, lower output MC versus higher, single full-range driver versus multiple etc. However, when we shut up and actually listen, we can plainly see this isn’t always the case - and certainly, preferences play their hand heavily here. And preferences can change over time - you’re allowed :)

I’ve done plenty of triode vs. UltraLinear comparisons on Rogue amps and prefer UL 9 times out of 10 (maybe more). Better dynamics and PRaT (or whatever you call it) for certain. I do play loud, and a lot of rock - certainly, that factors in. Triode has sweeter mids by a smidge, but it’s honestly so minor IMO. UL is awesome. Don’t confuse UL with "Pentode" mode. UL one of those rare compromises that leans very heavily into "best of both worlds" territory. It was hot sh*t when it was invented back in the 1940’s (!!), and still is. When I need a sweeter midrange (a common complaint in Rogue amps), rolling the right tubes moves the needle MUCH further than switching down to triode mode. That way I can get both dynamics, slam, and sweetness. The stock tubes can be fairly awful, honestly. I just put some Tung-Sol 7581A tubes in a Rogue ST100 I picked up for fun (office rig), threw away the stock JJ 12A*7’s (JJ’s go right in the trash), and holy crap this amp sounds amazing! Had a friend over to confirm. Yes, UL mode. I’ve owned Rogue's top-dog Apollo Darks before, own top-end VAC, and this little combo is somehow blowing me away right now.

@mulveling

There’s some paranormal audiophile force that makes us feel like the more "purist" approach must always be better:

I guess I had fell into that. The power of suggestion, perhaps?

Don’t confuse UL with "Pentode" mode.

I readily admit to how illiterate I am when it comes to electrical. Actually I had always thought that the one was a synonym for the other. I am in need of an education. Can you put into layman’s terms the difference between the three? If layman’s terms just won’t work because the subject matter is just too complex and it would take writing a book, I understand. I can live with just knowing that today I liked UL better today.

As an aside, the subject of the Mesa Baron amp (from the late ’90s) came up on this forum a few days ago. I actually took one home for a weekend, and I still have the Stereophile issue that reviewed it, and I am going to dig it out in the morning because I cannot remember if they said that it was switchable from triode to UL or switchable from triode to pentode. At the time I posted to that thread (the one I just alluded to) I was thinking they were saying pentode, but now I’ll have to look. The dealer who let me audition that amp said that the popular setting was 1/3 triode and 2/3 UL or pentode (as I just typed, I am not sure which). Anyway, at the time I was listening to my little Cary SLA70 and the difference was dramatic. The Mesa Baron literally filled the room with sound stage and put vocals right in my face. I thought it was pretty neat. I described the sound, shortly after, as "musky or smoky"; I remember that Margo Timmins’ (Cowboy Junkies) voice sounded kind of husky, which it usually doesn’t. But during the audition, it didn’t have a negative effect on me. The last thing I did, however, the Sunday night before I had to bring it back or buy it (and I was pretty much set on buying it) was to hook the Little Cary back up and I listened to the Cowboy Junkies cover of Sweet Jane either off of Trinity or their only (at the time) live CD, and it was then that I understood the meaning of "black background." Cymbals shimmering and hanging in the air. The Mesa Baron did not do that, and even though the sound stage, such as it was, shrunk to around the speakers with the Little Cary, I decided that it was not a good trade.

Anyway, I’ll dig that review out tomorrow to see if they referred to the Baron as switchable to UL or switchable to pentode.

@immatthewj you were pretty close on your thoughts and memories of the Mesa Baron amp. Appears that amp delivers 150Wpc in full pentode mode, 120Wpc in 2/3 pentode, 85Wpc in 2/3 triode, and 60Wpc in full triode.

Ask: so, which of the switch modes did you enjoy most with the Mesa Baron amp?

And yes, Triode, UItralinear, Pentode (hybrid) and full Pentode will all sound and present differently. Note - your Cary V12 and SLA-70 amp experiences with each of their own circuit designs Dennis Had created will have their own signatures as well. You know, and have heard it for years. It’s fine to just stop there and enjoy it too!

Hey, give yourself some credit here - based on how you’ve reported things so far, I tend to think your hearing and ability to discern differences might be just fine. Here is the key - you are hearing the differences now, and hats off to you for that!

I remember after messing with different solid state mosfet based amps for 30+ years, searching for that same lush sound, I eventually expanded into tube amps in parallel. I had all of the same [renewed] questions you have right now about the differences in sound with different tube amps, circuit designs, switch modes, and related tubes for each. As I reflect back, wow, had a lot to learn and still do, trying different things as you are now. Note: I got help from a few local tech legends and mentors, sharing their gear & tubes. Both upgraded my former tube and SS amps. 

Like you, and your V12, my modified V12R turned me into an EL34 tube geek. The Triode / UL switch gave an idea about both modes. And so did the SLI-80 with KT88s, which was an extension of your SLA-70, with the integrated front end and KT88s. Again, each of these amps and their own type of sound. Precise, maybe not, yet it might be a sound you prefer. I went through Cary, Inspire, and others trying it too. Worth every step along they way and appreciated every moment.

Welcome back to re-discovering circuits, designs, tubes and different applications through hearing the "differences". Probably the most important aspect to all of it imo.

If I may suggest, there might be a "next chapter" for you in your discovery, possibly moving to now try a (non-switchable) dedicated Ultralinear amp(s). Then trying a dedicated (non-strapped, true single ended) Triode amp with actual Triode tubes. You will hear all new difference yet again, in different ways, if you decide to try it in the future. Enjoy the renewed discovery and journey!

Every amp I have owned that was switchable between UL and Triode has sounded better in ultralinear mode, no matter the speaker efficiency. The only way to truly get the triode benefit is to have an SET amplifier and appropriate speakers.

I can only speak to the Manley Labs 200/100 triode switchable amps that I have used for quite some time.  I would imagine triode switchable amps do not all behave the same; in no small part due to the speaker they are driving and, importantly, what the listener considers to be “better”.  For those reasons I am suspicious of blanket statements about this issue one way or the other.

In the case of my Manley amps and the speakers that I have used them with what I hear is the following:

Triode mode:

- Tonally more refined.  Slightly smaller, but better organized and delineated soundstage.  Slightly smaller, but better defined individual images.  Overall, better clarity.

Ultralinear mode:

- More powerful and deeper bass range, but somewhat less detailed.  More bass “volume”, but less of the sound of the bow and rosin.  Slightly larger soundstage and correspondingly slightly larger individual images.  Depending on the music played, somewhat better musical drive (PRAT).  Darker, slightly thicker, even murkier overall sound.

When in my listening chair (usually Classical and acoustic Jazz), Triode is “better” for me.  When listening away for the sweet spot (usually Rock/R&B), usually at louder volumes when working out or other activity, Ultralinear is more satisfying (better?).