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

Ultra linear is a sexy term used by the manufacturer. Cary has not done a very good job to explain it on their website.

I think they’re taking advantage of the technology to promote something that is questionable as to sonic credibility. It’s not a very popular feature. I have never seen it before. Most people who buy this have no clue what it actually does only that it sounds different. It’s a rabbit hole and it’s clear when you read through this thread how confusing it is. Again a nice diagram would be nice.

Genius is the ability to explain involved complex things in a manner that can be understood.

Meaning that I guess he probably "voiced" the V12 in triode, but for at least the present moment, I am preferring UL.

@immatthewj IMO 'voicing' is a bad practice. I very much doubt this amp was 'voiced'.

I think the term ultra linear is marketing in nature and I dare say most people have no clue what they’re buying when they do.

@emergingsoul The term 'ultra-linear' was used to describe the invention that is the subject matter of US patent number 2710312A. You'll see it used in the text of the patent. Its an accurate description of  the time about a break thru in amplifier technology. Diagrams of how it works are at the link.

Loudness controls have to do with how the ear's frequency response changes with volume. Its a tone compensation.

WRT UL, It can be made switchable by having a switch connect the screen of the power tube to its plate as opposed to the tap on the output transformer.

Its not a marketing term any more than the word 'triode'. Its part of engineering lexicon.

A technical reference to triode in marketing literature makes sense, it’s not sexy. Ultra linear Whatever it is that it does is a sexy marketing term. If it’s switchable that’s probably discouraging a lot of people from taking it seriously especially in an amplifier.

@emergingsoul , at this point I am almost certain that you are troll posting. Did you actually read any of the circuit-technical posts from the more tech savvy members?

Here is an article from Wiki that I do not expect that you will bother with, but I’ll post a link anyway:

ultralinear

"Ultra-linear electronic circuits are those used to couple a tetrode or pentode vacuum-tube (also called "electron-valve") to a load (e.g. to a loudspeaker).

" ’Ultra-linear’ is a special case of ’distributed loading’; a circuit technique patented by Alan Blumlein in 1937 (Patent No. 496,883), although the name ’distributed loading’ is probably due to Mullard.^[1] In 1938 he applied for the US patent 2218902. The particular advantages of ultra-linear operation, and the name itself, were published by David Hafler and Herbert Keroes in the early 1950s through articles in the magazine "Audio Engineering" from the USA.^[2] The special case of ’ultra linear’ operation is sometimes confused with the more general principle of distributed loading."

And apparently, if you are not troll posting, you do not believe that switches could be used to toggle between two circuits, even if it was not the optimal way of achieving either circuit?

@decooney , I found the receipt for the Mundorf capsI bought from PCX:  they were the 71552s (0.22 uF 1000 Dc Supreme SilverGoldOil) @ 52.68 each.

@immatthewj

A technical reference to triode in marketing literature makes sense, it’s not sexy. Ultra linear Whatever it is that it does is a sexy marketing term. If it’s switchable that’s probably discouraging a lot of people from taking it seriously especially in an amplifier.

The manufacturers don’t really provide much info on what’s being done. A nice schematic would be nice because it does get involved.

Audio manufacturers do an abysmal job explaining what their products do. It’s a mystery box and you really have to dig in to figure it out.

There are clearly harmonic changes with tube amplifiers that are especially appealing unless you enjoy clinical accurate Music which is less than enjoyable a lot of times.  It's all about the quality the recording after all and there's only so much you can do to improve it and that really really sucks that they didn't get it right to begin with we have to spend a lot of money to enhance and bring out the best of what it has to offer

@immatthewj here are the 80510 units I put in the Cary V12R and Quicksilver Mono 120s.  From the Partsconnexion site.  

Mundorf Capacitor 0.22uF 1000Vdc MCap® Supreme EVO SilverGold Black SESG Series Metalized Silver Gold Polypropylene Axial

SKU: MUNDORF-80510

MSRP: USD $59.88

Unit of Measure: Each

@emergingsoul

I think the term ultra linear is marketing in nature and I dare say most people have no clue what they’re buying when they do.

But ultra linear does drift more toward solid state and isn’t that what we’re really saying overall after all

I am not sure whether you are just troll posting, but assuming that you are not, do you also feel that, for instance, single ended triode is also "marketing in nature"?

the differences between modes of operation which on this amplifier tend to be switchable so easily which always raises skepticism

Are you also skeptical about the sonic differences between different vacuum tubes because it is quite easy to swap them out? Adjustable feedback? For that matter, do you believe that possibly the whole concept of vacuum tube gear is also a marketing ploy, and underneath it all lies solid state circuitry?

Just curious.

Does your V12 still have the original Audio1 coupling caps installed in it?

@decooney , no, it came with Jensen caps, and so far that is the only true failure (one of those original caps), and I won't go into the details, but I think that may have been my fault.

Anyway, I think you and I may have discussed this as well; I replaced all four caps and went with the Mundorfs. (I'd have to look at the receipt, but I am pretty sure they were the most expensive Mundorfs that PCX was selling at the time, so "air oil supreme" or something like that, but I'll check the receipt tommorrow and get back to you.  I think I remember you telling me that the caps I picked were okay, but would not have been your first choice.))

@immatthewj Also, when I last experimented with backing the bias off, I was listening in triode, and triode was another of my preconceived notions that I turned out being open to rethinking.

Thanks for taking the time to replay, you always offer a lot of insight when answering my V12 questions.

Does your V12 still have the original Audio1 coupling caps installed in it?

Worth flipping it over when you remove the tubes, pull the cover and check. Installing really good caps in that amp brings it to another level of enjoyment.

@mulveling

@gs5556

@atmasphere

Enjoyed reading all your comments to explain this technical area. Very difficult to understand things without a diagram and that’s what’s needed here.

I think the term ultra linear is marketing in nature and I dare say most people have no clue what they’re buying when they do. I remember loudness controls on a receiver I had a while back and was curious at times and clearly pushed more power through the circuits. It’s all about compromise which can be understood without getting terribly technical and my decision was to do biamping of a solid state and tube amplifier. At least the harmonics are more favorably affected and I do really like isolation of tubes in the upper area and let solid state handle the heavy duty stuff below. It seems to be working pretty well so far.

But again it would be kind of nice to see a diagram of all this to better understand the differences between modes of operation which on this amplifier tend to be switchable so easily which always raises skepticism in my tiny mind. But ultra linear does drift more toward solid state and isn’t that what we’re really saying overall after all

@decooney , I really liked the sound of my V12 with the Ruby branded EL34s it came with, and I am assuming that those were the same as the Chinese tubes you just referred to.  I don't think that I will be rolling any tube types other than the EL34s.  In an emergency I guess I might try rebiasing to two tubes perside, and trying those old NOS Tung Sol 6550s I got from Andy way back when.  Maybe.

I also remember a couple of conversations we had about biasing that amp.  I di try backing it way down, and I didn't think I liked it at the time.  But maybe that was a preconceived notion I had that low bias couln't be good.  At the moment I have both sides set at just under 270.  As long as I am experimenting with different things, I'll back it off tonight.  I was thinking about 240 mA aside and going from there.  Also, when I last experimented with backing the bias off, I was listening in triode, and triode was another of my preconceived notions that I turned out being open to rethinking.

Thanks for taking the time to replay, you always offer a lot of insight when answering my V12 questions.

@immatthewj Not exactly. But its likely that one tube type in that list will perform better than others. That’s a bit different from saying that it will ’work’; sure it will play but the output transformer should be optimized for a particular tube.

@atmasphere , although I do not understand circuit topology what you write does make sense. I’ve often found that tools that are advertised as fulfilling multiple functions do not work as well as a tool that is designed to perform one specific task. And hand tools are much simpler to understand and work with than circuits are.

As far as rolling tubes, I am not trying to speak for Dennis Had, but from reading the writeups he provides for several of his products (including the V12, from which I sort of recently quoted the manual), I sort of get the impression that he likes tube rolling. I remember reading one of the blurbs he wrote for one of his fairly recent SET amps, and he described it as (I belive the words he used were) ’a tube roller’s dream.’ Anyway, as far as the V12, after reading through the recent posts I am going to assume that it was "voiced" (I’ve read that term elsewhere) for the EL34 and after reading the recent responses on this thread, I am not going to mess around with other tubes. (Although I do have three different quads of 6550s for another amp that I am not using right now, and if worst came to worse, I could drop one of those quades in and bias the amp for two tubes per side). I’d also note that in the manual, Mr. Had writes about the virtues of the triode circuit toplology, and from what he writes about the V12, I am assuming that he includes the V12 in pushpull. Meaning that I guess he probably "voiced" the V12 in triode, but for at least the present moment, I am preferring UL.

@xenolith , I was going to jokingly type thgat you are a buzz-kill, but a lot of jokes are not taken as such. In reality, I wouldn’t be surprised if you are correct. I don’t have much of a grasp on the subject of circuit topology and back when I was setting up my system (the ’90s), I didn’t have a computer and didn’t know about A’gon, and what I learned was from reading Stereophile, what dealers told me, trial and error, and what manufacturers and their tech guys told me when I called them to ask questions about their products.

Anyway, if I NOW had the wherewith all to start completely over from the ground up, I would do a lot of things differently. However, I retired early and I made a few bad life choices before Idid, so I am probably going to find a way to try to be as happy as I can with what I have. But I will add that before the V12 I had a couple of strictly UL products, including a pair of ARC VTM120s which I have referred to previously in this thread, and if they were more relaible than they turned out to be, I’d still own them, and although aural memories (at least mine) are often flawed, going from the ARCs to the V12 was, at best, a lateral move. As far as the sonic presentation, that is. But when I flip the switches to turn the Cary on, I do not have to cross my fingers, and that is worth something.

Yesterday afternoon going into the evening I put five more hours in in the UL mode.  I note a "fuller" presence in UL that I was getting in triode mode.

I won't go  blow by blow into yesterdays session, but I'll mention a couple of things that stood out (from yesterday).  I have been planning (for some time) on listening to to a couple of SACDs (Jacintha Goes To Hollywood and Patricia Barber/Modern Cool) but I never made it past digging out red book CDs that caught my eye and then my ear.  I saw a movie a few nights ago on TV that reminded me I owned Chris Isaac/Heart Shaped World which I bought in 1990 but never listened to all the way through.  Probably over produced for my usual tastes, but the sound was was room filling and it sounded quite good.  I bought Brandy Carlile/The Story quite a few years ago because I heard her sing The Story on my car radio, and I thought that I would like to hear the choruses in which she was literally screaming on my system, which, in theory should sound way better than  the AM/FM radio in whichever vehicle I was motoring about in at the time.  But the playback on that one never met my expectations.  I put in that CD (The Story) yesterday specifically to hear her sing The Story, and I can honestly say that I was struck by the visceral impact of the choruses more in UL than I had been in triode.  I actually wound up listening to the whole CD, and it does have a nice sound.  (It was one of the CDs that kept me from getting to those two SACDs by Jacintha and Patricia Barber, but I am leading off with them tonight.)

However, with all that typed, I will also say that my initial reactions could be the "new toy syndrome"; I am admittedly prone to that infection.  Also, as noted before, my hearing is changing and not for the better, I have introduced different speakers to my system, my system now resides in a different room than it did when I first set it up, and the way I listen has changed significantly over the years..

Thanks Ralph, you are always a breath of fresh air.

@emergingsoul , at on or about the 16th reply to this thread, at my request, @mulveling  did provide a description of the different (triode, ultralinear, and pentode) topologies..

@mulveling 

Out of all the possible questions to be asked on this forum, this is one I would never have expected before now. No, UL is not solid state. And it’s about as much a marketing term as "gravity" or "electromagnetism".

You have a way with words.

So if the manufacturer spends the extra money for a UL winding they would, seemingly, have optimised it for the tube type and circuit.

@viridian This assumes that the manufacturer knew about the patent and designed according to it rather than the tradition that developed trying to get around it. In a way, David Hafler might be the one responsible for that; he was one of the inventors when he was at Acrosound, to whom the patent was assigned. When Hafler moved to Dynaco the patent didn't go with him but he knew full well how to get around it. So its reasonable to assume that Dynaco OPTs are not optimized.

So a rational thinker, in possession of that knowledge, might conclude that the UL taps were improperly placed, causing the triode setting to work better. However, a rational thinker might also wonder if the OPT had windings to accommodate the difference in the plate load impedances required since that value for a given tube is different for a pentode as opposed to the same tube wired in triode.

I'm certainly wondering that. Whether I'm a rational thinker is another matter.

@ghdprentice: I, and presumably atmasphere, and all other rational thinkers, would rationally conclude that your amps are optimized for triode topology...and, necessarily, that the ultralinear topology was added, presumably as a gimmick, to presumably, attract more purchasers. Let’s hope so anyway, as the other option is that the amps are not optimized for either topology and that you and the other folks just like the same not optimized topology over the other not optimized topology.

That is exactly what you said.

No back pedal. I’ve told the forum what I said; please tell tell us what you think I said.

That is hardly all that you said, but I appreciate the back pedal. We will agree to disagree and leave it at that, logical fallacy, or no.

From a design perspective, ultralinear taps must be added to an output transformer at the manufacturing stage. They have a cost associated with them, a PP output transformer designed strictly for triode operation would be less expensive without the UL winding. So if the manufacturer spends the extra money for a UL winding they would, seemingly, have optimised it for the tube type and circuit.

That's not what I said viridian.  What I said is that there are two rational conclusions that can be drawn from the information provided, and that for ghdprentice's sake, I hope it's one conclusion instead of the other that he is experiencing.  If you think there are other rational, not irrational conclusions, that can be drawn, then please, tell us what those are. 

LOL, those that agree with you are rational and those that disagree irrational. Argument from incredulity is a logical fallacy.

@ghdprentice: I, and presumably atmasphere, and all other rational thinkers, would rationally conclude that your amps are optimized for triode topology...and, necessarily, that the ultralinear topology was added, presumably as a gimmick, to presumably, attract more purchasers. Let’s hope so anyway, as the other option is that the amps are not optimized for either topology and that you and the other folks just like the same not optimized topology over the other not optimized topology.

I always run my ARC Reference 160s or 160m's in triode mode. If I unplug it for some reason and it defaults back to ultra linear within a minute of listening I will start to wonder what is wrong...the hardening of the midrange, the reduction in rhythm and pace. I find rhythm and pace is almost always superior in triode mode... either design or when amps are switchable. 

Other folks that have heard my system and I have switched back and forth, I think all have preferred triode, an commented about being more musical. 

@immatthewj "Again, with not intent of being argumentative, does this sound incorrect? (I was actually asking @decooney if he had rolled any tubes besides EL34s as I do have some 6550s for another amp,"

Sorry for the late reply this week. No, I did not, chose not to. I was sort of enamored with the Shuguang EL34BSTR (Ruby labeled) tube that Dennis chose for that amp at the time. Note I had two colleagues with V12Rs at the time, which offered the small [odd TV tube 12bz7] option up front, along with EL84s, and combined with those specific EL34 output tubes AND mixing in the later version Mundorf EVO Silver Gold (non oil) coupling caps was the ticket. Some guys went on to KT88s in the amps, and the tubes are too wide (imo) for that amp, sitting too close to each other. THIS is also why I’d stick with good EL34s, narrower tubes, more air spacing between the tubes. Good EL34s work in that amp.My local retired tech friend listened to the amp at his house and compared with different amps at the time. That combination of it all just worked well together. Sounded pretty amazing, actually. However he cautioned me about turning up the bias too much - and I did not. However as the V12R original manual recommended (280ma per side). Not good. Too hot. We got on the phone together with the designer that replaced Dennis at Cary later on. All of us agreed to run those tubes and to back the bias down a lot more. At the original manual spec, it just ran way too hot imo.

That tech [no longer there] told us the V12R factory original manual needed to be updated - Cary did not update it, new boss did not care - heads up. I was at 230 a side for a while [38.3ma per tube] and even the sound at 200ma per side kept the tubes sounding close, running cooler, and everything was still happy. Long story, be careful, those big transformers are very expensive to replace, and the R version had that large one in the back. Std V12 has the smaller transformer unit, both the same size, which might be easier to replace.Not sure if you run yours too hot, just beware.

My local tech friend was surprised by the sound of that amp I had - once upgraded, yet he got all over me about the wire maze in that unit, switching, modes. Kept pushing me to dedicated monos in UL or triodes. That V12R amp caused me to want to try two separate mono amps with KT120s/KT150s. 1/4 the output tubes, half the weight divided into two amps vs massive unit. Easier for amp rotation too. So, next I did the exact same cap and small tube rolling in the new mono amps with the idea of biasing the tubes [in the window] while keeping the main power transformers running a bit cooler, tubes running cooler - lasting longer too fwiw.

In summary: Does the new UL design mono amp setup have that same rolled off euphoric sound as those banks of EL34s, in the Triode switch position (no). Not the same. Is it a bit more clean sounding and more dynamic and extended, not rolled off, in a dedicated UL design mode with fewer tubes, (yes). Yes, you can run just two EL34s per side in that amp, if you can drive your speakers with lower power.

Even after using the exact same coupling caps [identical], It took me a while to adjust to my new mono UL amps. I too had been listening to that Triode switch mode for a long time. And, I agree with @atmasphere’s comments, UL is just quieter, cleaner, less distortion, offering something closer to your own renewed and updated realization about the sound in UL switch mode. Glad you tried it again.

I’ve stayed here [with self restraint so far, LOL] trying to avoid going with two larger dedicated 211 / 845 Triode amps. Btw, LOL I had that same B&K preamp, and three of the EX-4420 dual mono lush mosfet SS amps for a few decades before the various Cary tube and solid state amps by Cary. If you need the power for any reason, I will say the two separate beefy UL mono amps seem to drive and control my custom multi-driver speakers really well. They just light up and fill the room more easily. I think if I sold my existing mono UL tube amps I’d really kick myself later, fwiw. We all get the bug to try something else, yet keeping a few of the good ones around is nice too, if you have the space for it. Good fun. Enjoy.

All I know is that on my system some music cds sound better in ultralinear but most sound better in triode.

I’m a big fan of high definition music (Blu-ray audio primarily). Nearly all of them sound better in ultralinear.

i have a horn system with a tube integrated amp fed by an oppo UDP-205 with the Modright magic tube modifications.

+1 @ozzy62, you said it all. I’ve owned 4 amps switchable between triode and UL, still have 2, and have auditioned a few others in my systems. Each is better in UL. This is true on all 6 pairs of speakers that I currently own, ranging from 86db to 102db. OTOH, I have 2 SET amps that sound better on my high-eff speakers (102, 99 db) than any of the UL amps. The triode option on a UL amp is simply not the same as a purpose-designed SET.

Like anything, UL and triode will be a bit different with every amp and every system.  With my system with the Dynaco/VTA mods, triode is more refined with a more concise soundstage.  Especially notable with simple vocals, piano, and string, etc.  It's tougher to tell with more layered complex recordings.  My amps are monoblocks, so once in a while for giggles I'll flip one amp to UL, rebalance, and leave the other amp in triode....ultra triode?     

"I think use of the word ultra linear is a marketing term and kind of dumb"

Some posters never fail to... Sigh/shoulder shrug

Keyboard  strokes away for basic amp electronics knowledge 

https://www.analogethos.com/post/screen-ultralinear

atmasphere said: That’s a bit different from saying that it will ’work’; sure it will play but the output transformer should be optimized for a particular tube.

This is almost certainly the most salient content that this thread will produce. You want to hear great UL sound reproduction? Build an amp that uses KT77 output tubes...the only tube ever produced explicitly to run in UL mode, and specifically at a 43% winding tap and, of course, use output transformers...yep, with a 43% winding tap! As an aside, because the KT77 can handle big current, as long as you specify driver and splitter tubes that can handle big current (like 6BL& or 6BX7) and you use big inductors (on both input and output) to smooth that big current, you can do away with significant capacitance...this yields a very powerful, very dynamic, very fast and very linear, no, make that ultra linear amplifier!

Hate to break it to the assembled, but an amp that can run multiple tube types is not optimized for any of those tubes, neither is an amp that can run multiple topologies optimized for any of those topologies; IMO, an amp that does both represents the antithesis of high fidelity. I avoid them.

Isn’t ul mode solid State? Doesn’t it make sense that more would be involved for solid State and that it would sound a little bit

I think use of the word ultra linear is a marketing term and kind of dumb

Out of all the possible questions to be asked on this forum, this is one I would never have expected before now. No, UL is not solid state. And it’s about as much a marketing term as "gravity" or "electromagnetism".

Isn’t ul mode solid State? Doesn’t it make sense that more would be involved for solid State and that it would sound a little bit 

I think use of the word ultra linear is a marketing term and kind of dumb

The V12 is a very nice amp especially when upgraded with really good coupling caps and some large value polypropylene caps bypassing the electrolytic caps.  Like 10uf to 20uf propylene’s.  This will really open it up. 
As far as UL or Triode it depends on taste, speakers, etc. especially with EL34’s.  Those are a typically warm sounding tube anyway and can sound very nice in triode.  Usually in UL you hear deeper bass, more extended highs and better detail.  Some amps may be different depending on the plate voltage they’re running the tubes at.  With KT88’s, KT-etc I usually prefer UL. 
Now if you’re talking real Triode tubes like 300b’s, 845’s, etc this is where triode gets really good.  300b’s are great with horns and such as for me anyway, they lack the deep bass and extreme highs and so with many dynamic speakers I don’t enjoy them fully as I feel there’s always a bit missing. 
Now you hook up a pair of 845 single ended amps like the Cary’s or something and wow!  Now you’re talking triode sound!

but in the manual for the V12, Dennis Had is saying that tubes that can be roled in this amp include;  6L6, KT88, 6550, KT90, KT66, "even 6V6."

Again, with not intent of being argumentative, does this sound incorrect? 

@immatthewj Not exactly. But its likely that one tube type in that list will perform better than others. That's a bit different from saying that it will 'work'; sure it will play but the output transformer should be optimized for a particular tube.

Slightly/Way OT, but found this pic interesting as far as perception goes...

https://scontent-mia3-2.xx.fbcdn.net/v/t39.30808-6/468911527_992740516228534_9133954768681984968_n.jpg?stp=dst-jpg_s1080x2048_tt6&_nc_cat=110&ccb=1-7&_nc_sid=127cfc&_nc_ohc=6QLE1wm-_BAQ7kNvgEGZsmt&_nc_zt=23&_nc_ht=scontent-mia3-2.xx&_nc_gid=ASYFoaP-Bd1gVOBh_gs80VH&oh=00_AYDjOKG6Zua5q2lb9j83_MZ35Tj84zu9knOdUVJlHl_46Q&oe=67568AAF

DeKay

The more refined my system has become the more I default to ultralinear especially 

@bolong , and I will say that when I brought this V12 into my system primarily in triode mode my system was less refined that it is today, twenty three years later after the preamp and digital front end upgrades, and possibly the speakers as well.

The more refined my system has become the more I default to ultralinear especially so with the addition of Audio Magic M2 fuses to several components which seem to make all aspects of the music sound more "behaved."

It's always a pleasure to read about a fellow hifi enthusiast who has owned and enjoyed decades of music through their gear!

@jimmyblues1959 , it's been "a long strange trip . . ."  (Not really, but it was fun to say.)  

I have no recall, was I rude? Mean? I've regressed to teenage behavior?

No, @elliottbnewcombjr , it seemed pretty much made in jest and that's the way I took it.  But I remembered the convo yesterday as I was listening.

@atmasphere 

which is why you can't use the same output transformer with EL34s and 6L6s unless there is a tap for each tube type.

I am not arguing with you because I have already admitted that I am rather cluelss about how this stuff works,

but in the manual for the V12, Dennis Had is saying that tubes that can be roled in this amp include;  6L6, KT88, 6550, KT90, KT66, "even 6V6."

Again, with not intent of being argumentative, does this sound incorrect?  (I was actually asking @decooney  if he had rolled any tubes besides EL34s as I do have some 6550s for another amp, and I can bias the V12 for just two tubes aside.)  Reaching out to Dennis, who is no longer with cary, about an amp he made over 20 years ago is probably a dead end, and as far as this goes, I definitely want to stay on the "better safe than sorry" end of any deal.

OP wrote

@elliottbnewcombjr 

I remember a convesration we both particiapated in about someone's SLI80.  I believe you made a reference to face slapping when I stated I preferred my V12 in triode.

I have no recall, was I rude? Mean? I've regressed to teenage behavior?

It's always a pleasure to read about a fellow hifi enthusiast who has owned and enjoyed decades of music through their gear! 👍

@silverfoxvtx1800 

wow!  I had a pair of ARC VTM120s that intermittently blew grid resistors on start up.  And I thought that was bad!  Those ARCs were pussy cats and replacing grid resistors was a minor inconvenience compared to what you just described.

@ozzy62 , I will say that reading what the owner/operators of SETs have written about the experience has always sounded intriguing, if not tantalizing.  I sort of have a fantasy about higher efficiency speakers and one of Dennis Had's Inspire setups.  But that ship has sailed for now.  Maybe that is why I was so dead set locked in about triode versus UL--I thought it would be the next best thing?  Maybe.

@frogman your perception of triode versus UL is also interesting.  I suppose the possibility does exist that I am preferring UL at the moment in my sweet spot is due to it being different.  Different is often exciting.

@viridian 

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

Yes it does!  And that may be where the power of suggestion comes in to play and why I was previously unwilling to give UP any serious time beyond ear-bleed rock-out sessions.  I also hate to admit that it was probably Dennis Had who turned me into a fan of Female vocalists.  The power of suggestion again.

@freediver 

I do however believe this is speaker dependent

possibly, and up until this spring I was always using the V12  in triode to drive a pair of B&W 805 Matrixes.  

@elliottbnewcombjr 

I remember a convesration we both particiapated in about someone's SLI80.  I believe you made a reference to face slapping when I stated I preferred my V12 in 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.