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

@gs5556 Your explanation is partially correct. The bit about 'partial triode' is not. What UL allows is for a pentode to have better linearity than a triode.

However there's been a wrinkle caused by the fact that the UL technology was the topic of a patent. To get around it, other manufacturers moved the taps away from the ideal point as taught by the patent. The linearity goes down rapidly. The patent also taught there was an ideal percentage for the tap that depended on the power tubes being used, which is why you can't use the same output transformer with EL34s and 6L6s unless there is a tap for each tube type.

The use of the incorrect tap has become a tradition and is now so ingrained that everyone thinks 40-43% is the right ratio; so UL operation it typically incorrect. I think that's part of why you see debate around 'UL vs triode' in high end audio. Depending on the amp, triode may or may not be better as a result. So its good in the case of the original post that the Cary seems to have gotten this bit right.

UL mode is a pentode in "partial triode" mode. The screen and plate are operated at the same voltage and when the screen is tapped at the load (plate) it's triode mode and pentode mode when the screen is tapped at the B+ of the transformer. In between the two is the UL tap (about 40 to 43% of the winding) and that provides a negative feedback to the screen, resulting in lower distortion in push-pull operation.

I have a KT150 P-P. In UL mode it sounds like a solid state amp -- clean, tight transients and excellent bass response. In triode mode it's a little more syrupy and tube-like. I prefer the triode mode.

@mulveling , thank you for taking the time and effort to type out that explanation. I am going to print it and try reading it slowly and thoroughly to digest it. I think that you probably did a good job, I struggle with electrical. When I was in HS the Air Force recruiter told my mom that I did "real well on electrical on the ASVABs." I don’t believe that he was telling her the truth. When I finally did go in a year later, they were, "Sorry, son, electrical is full--how about open mechanical?" (Meaning airplane grease monkey.) Probably a good thing electrical was "filled up." I doubt I would have been good at it. Anyway, I think you are right about "better than death."

@atmasphere , thank you also for the explanations. I was pretty sure you would have a handle on this stuff. I now wish that I had gave UL a SERIOUS whirl (as opposed to the short try outs or ear bleed sessions) before this. Not that I didn’t like my amp in triode, but now I am thinking it is "more better sounding" in UL. Thanks again for the feed back.

Everything was great at first then after a couple months the problems began, when I would turn everything on after a hour the amp would make the most awful load noises like metal bending and it was loud. That went on no matter what I would do,there was no support to help me…it was one of those things you could not find, then after a year or so the stock tubes started shorting out, getting that red light on start up, and fuses blowing at the same time…the wife and I would look at each other when I turned it on, holding our breath..the sound with the Fortes was ok not great

@silverfoxvtx1800 Ooof! I don’t know how on earth you had so much patience and/or capacity for self-abuse on that front! Months...a year later? I would’ve hit my tolerance limit at or before "a couple days" at most. If I thought my speakers were at risk it’s not going back on, period. And if the dealer / distributor / manufacturer aren’t willing to assist (sounds like a lemon unit), then frankly it’s going in the trash - and I'd let plenty of fellow audiophiles know what I think of said dealer / distrib / manufacturer. And then you say it didn’t even sound that great, to boot! Life is short man - find something else that brings you joy.

I was just pulling your leg. Its a bad habit I have.

@artemus_5 , you asked a legitimate question--I didn't take any offense to it.  After all the time I spent swearing that triode was a superior sound, I hated to admit that after yesterday I feel that I may have been mistaken.

@decooney 

@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?

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. 

I found that issue of Stereophile, and what a looker that amp was!  Dual monoblocks in one chassis, rack handles, meters, switches, knobs, a dozen output tubes . . . that, unfortunately, was probably a lot of the reason I was initially intrigued with it.  (A guy I used to work with used to say I was like the Indians who sold Manhattan for some shiny trinkets.  He may have been somewhat correct.)  Anyway, Anyway, I also found the flier from Mesa for The Baron that the dealer gave me (I had the flyer inside the Stereophile) and Mesa was saying that the amp utilized "pentode."  As far as which mode I preferred, well, I spent very little time in full triode or full pentode, most of the weekend was spent in 1/3 triode 2/3 pentode per dealer's advice, and I actually was intrigued and initially liked the presentation until I did the A/B I typed about.  At the time, I was using a B&K digital HT (prologic back then) preamp, and I had a dealer in Philadelphia who had set me up with that first system (the B&K and the SLA70) and I talked to him about the experience and maybe upgrading to a pair of SLM100s to get the sound stage without the "smokiness" and he told me (and I will have to paraphrase) that 'the Baron is a chameleon'  I do remember he did use the word "chameleon" and the sound I heard was due to the level of preamp.  Which may have been true.  But I didn't buy SLM100s from him.

What I did do not a whole lot later was to buy (through the classifieds in the back of Stereophile)  a secondhand pair of ARC VTM120s, four 6550s each, 100 wpc in NONSWITCHABLE UL.  And I like those ARCs, I really did; they would rock out (and I mean ROCK OUT) or whisper . . . and it was CLEAN sound and that was with the B&K in front.  And then, another aside, but still another local dealer had a second hand modded SLP90 that I took  home for a weekend, and then and there I learned the difference a preamp can make.

The reason I didn't keep those ARCs (I still have the SLA70, btw) is that they had a random habit of blowing a grid resistor on start up.  And taking one of them down and desoldering and resoldering grid resistors is no way to start a listening session.  I used to grit my teeth and cross my fingers when I flipped the switches.

Anyway, when Sterophile reviewed the V12 I was intrigued by the switchable from triode to UL feature and I knew that back then (in the Dennis Had/Kirk Owens days of Cary) I found my SLA70 to be reliable and Cary's tech support (when needed) was superb, so I took the plunge and bought a V12 from a dealer in Colorado, sight unseen.  

And that's how I got to the V12.

Thanks for the great post, and with your V12, did you roll any tubes besides the EL34s?  Like 6550s for example?  I do note that in the owner's manual, Dennis Had was saying one could do that.  I have about three good quads of 6550s for my SLA70 (six of NOS Tung Sols 6550 from Andy in Michigan, a quad of Svetlanta 6550Bs,  and I think a quad of KT88s, but I'd have to look to be sure, hat were branded "Tesla" that I got from Audio Advisor).  I was thinking of possibly biasing the amp for two tubes aside someday, and trying it in UL with 6550s?  I tried four tubes aside once back in '18 or '19, but I have to confess that this was back in the days when I was swearing by triode, and I wasn't crazy about it.

@mulveling 

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.

Thank you for saying it. This was my initial thought. It's easy to take the consensus opinion even when it may be wrong. I suspect we all have done it about something. But it shows the importance of testing everything for ourselves.

@immatthewj 

Well, I guess because for nearly 23 years I steadfastly maintained that triode sounded more refined and also "more better." Perhaps I was wrong about "more better."

I was just pulling your leg. Its a bad habit I have.

I prefer my Cayin A-88T's ultralinear 45 wpc to triode 22 wpc. My horn speakers are very very efficient, so I do not think it is related to the extra power, there seems to be a fuller more natural sound, similar to the change from 6550 tubes to KT88 tubes.

With the tube amps I’ve owned that can switch between the two modes of operation I always ended up preferring Ultralinear mode,mirroring your findings of better imaging definition,slightly forward staging & more "meat"on the bones in the bass & upper bass...I do however believe this is speaker dependent..All of the speakers I had at the time were already naturally warm sounding(Harbeth M30.1,Fritz Carbon 7SEMk.II & Sonus Faber Lumina III),negating the benifits Triode mode provides...With a speaker that has some tendency towards a more lit up-forward tone(Triangle-Kef-Klipsch or anything with metal drivers) I think Triode mode might be the way to go...

Of course, a pentode tube strapped for triode has two physical elements within the tube that are shorted, so not functional, which is quite different than a tube designed as a triode, so it is not surprising. For a triode strapped pentode, power output will also be roughly half, at a higher output impedance, so required speaker damping and epdr probably come into play as well.

It says right in your owners manual that the designer, Dennis Had, preferred the amp in triode, for whatever that is worth.

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.

@immatthewj I’m no circuit analyst or electrical engineer, so I’m possibly not the guy you need to hear this from. But I’m a computer programmer who often has to explain things to people with a tenuous grasp of coding, so I’ll give it a crack lol. Based on my limited understanding, what differentiates a tetrode / pentode (call these both "pentode" from here on out, as the 5th element is not relevant to this discussion) from a triode is that the former have a screen grid that triodes don’t. The screen grid is positioned between the control/signal gird and the plate (the biggest metal part you see in a tube). You can sometimes spot it through the plate holes - its coiled wire is spaced out much more than the tighter control grid coils.

When you run these amps in "triode" mode, this screen is tied directly to the plate, and basically acts like it isn’t there (mostly). When you run them in "pentode" or UL mode, the screens are wired to the output transformers, but these 2 modes differ in exactly HOW they are wired to the transformer. Basically, UL is more cleverly done so that its distortion levels are much closer to triode mode than pentode (lower is better) and its power output is much closer to pentode mode than triode (higher is better). So you really do get "the best of both worlds", sort of. The output transformers do need to be designed with UL mode in mind for this to work. But frankly, it would be very odd to encounter an amplifier with only a "pentode" mode instead of UL (UL mode was devised in the 1930s and became common since the 1940s, e.g. the "Williamson" amplifier - incidentally, every time I hear of that "Wilsenton" Chinese amp brand I think that must be an Engrish-mangling of the name "Williamson"!). And those which offer switchable triode vs. "pentode" modes should also be rare - in those cases, you should probably just stick to triode. The only meaningful choice is triode versus UL. And in my opinion, borne out by when I’ve tried this - if you’ve got tetrode / pentode tubes running in your amps, you really want to be running UL mode. That’s the best use of their design elements.

True power triode tubes, DHT, and SingleEnded (these 3 often go together but not always!) are other balls of wax - I’ve heard them a couple times and don’t think they are for me. At least, I haven’t been won over yet. I listen loud and feel like I benefit too much from the extra power of UL mode. Give me tubes which slam, or give me solid state! (that’s better than death, I guess)

@immatthewj If the UL taps are set up properly, the amp should have less distortion in UL mode. FWIW, this was well understood in the 1950s when UL was first patented. Distortion obscures detail; so if the output transformers are properly designed it should be no surprise that the UL mode sounds better.

A secondary aspect of this is power tubes in UL mode are easier to drive than the same power tubes in triode mode. So the amp very likely is also making less distortion on this account too.

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?).  

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.

@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!

@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.

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.

The only thing I can think of, your amp is more effortless in ultralinear?

@grislybutter , I was thinking along those lines myself. The Revels (sensitivity 86 and minimum impedance 4.7 ohms) are supposed to be an easy load to drive (according to the reviews) and I didn’t think that the amp was straining in 50 wpc triode, but maybe it was and I didn’t know it.

@audphile1

It’s not night and day but enough to hear.

Yes! That’s the way I would describe it. I still haven’t tried A/Bing those PCs from Amazon, the Preffairs (sp?), but if there was a difference with those, it was subtle to the point that my untrained ears were unable to detect it. With that typed, my ears are not that great (and those PCs have been in the system for a while now, so now maybe I would). However, I immediately heard this today, as in immediately, and although it didn’t sound like a whole different component, if I could hear it, with my ears, that says something. As I typed previously, today I liked it.

@artemus_5

not sure why you "hate to say it" that UL sounds better than Triode.

Well, I guess because for nearly 23 years I steadfastly maintained that triode sounded more refined and also "more better." Perhaps I was wrong about "more better."

@tablejockey

Your hearing isn’t as sharp as it was. Now UL is needed to "push" instrument passages closer to please the ear. That’s my personal diagnosis as hearing degeneration and tinnitus take over.

"In UL the voices seemed closer to me than I remember them sounding in triode."

My experience toggling between the 2-

Triode-instrumentation is pushed back with vocal taking center stage.

UL- instruments pushed forward just behind vocals.

I am willing to concede that my hearing is worse now than it was when I bought that amp. And considering that I spent a lot of my adult life around jet engines and hammering rivets with inadequate hearing protection, I often wonder how good it ever was back when I started my personal quest for "better sound." Your description of UL versus triode I think is what I was getting today. I’ll pay closer attention tomorrow.

@decooney , I was meaning to ask you about your feelings of triode versus UL with your V12.

Makes sense.  I owned the Cary V12R and the Carly SLI-80 both, and yes hat's how it sounds between UL / Triode switched modes over several years.  

With those amps, Triode switched mode will have rounder top and bottom end. sounding softer. Ultralinear switch mode will be more dynamic and controlled, not lacking in top or bottom end.  

While I listened mostly in Triode modes at first with both Cary stereo amps, I later compared to my current Quicksilver Mono 120 tube amps which are dedicated Ultralinear circuit design - there is more clarity and dynamics to it overall.   

@tablejockey excellent point! 

" For most of the twenty three years that I have owned this amp I have always felt that I preferred triode"

Your hearing  isn't as sharp as it was. Now UL is needed to "push" instrument passages closer to please the ear. That's my personal diagnosis as hearing degeneration and tinnitus  take over. 

"In UL the voices seemed closer to me than I remember them sounding in triode."

My experience toggling between the 2-

Triode-instrumentation is pushed back with vocal taking center stage.

UL- instruments pushed forward just behind vocals.

The jury is still out on this, but I do have some CDs in mind that I want to listen to over the next few days as I continue to evaluate.

Sounds like a good thing to me if music comes to mind and then to your system. not sure why you "hate to say it" that UL sounds better than Triode. I've said it for 15 or so years. Triode does not have enough bass response for the drummer in me.

Yes UL was more forward and more dynamic with the Rogue amp as well. It’s not night and day but enough to hear. It’s almost like having two amps. Awesome 

fascinating (if only I understood more than 51% of it), but still... and I am on the same page about the vocals.

The only thing I can think of, your amp is more effortless in ultralinear?

@audphile1 , I felt as if the instrumental work  (as I typed, particularly what was in the center) had a bit more texture and therefore was bit more palpable sounding when I switched over to ultralinear.  This was after listening to the same (instrumental) "Jazz Essentials" CD twice in a row.  After switching to UL I listened to most of it for a third time and I felt as if the instruments had more "bite" (if that's the right term).  

As far as vocals, I didn't start listening to music featuring a human voice until after I switched to UL, but vocal work is mostly what I do listen to, and in UL the voices seemed closer to me than I remember them sounding in triode. (Cary claims it is okay to switch that amp around "on the fly", so I guess I could have done that, but I didn't).   Anyway, I prefer the "up front" presentation, so today it was working.

But who knows with my bipolar hearing . . . tomorrow I wouldn't be surprised if it all   sounds like hammered dogcrap in UL; but for now it is striking me as a bit of a sonic revelation.

I had a Rogue ST100 that I could switch between Triode and Ultralinear. 
I believe it was around 60w in Triode mode which was more than enough with the Martin Logan Montis speakers I had at the time (powered woofers). 
In Triode mode the sound was more laid back and the presentation was slightly more intimate. The mode I had the amp in was influenced by my mood most of the time. I can’t say one was better than the other.

Use whatever mode you like. When you get tired of it you have a second mode to switch to. Beauty of having a choice.