To @xenolith, agree, yes, you are fortunate to own those very unique and interesting big blue amplifiers from Gary and Charlie. I love one-off boutique custom builds like this with audio, cars, and motorcycles. Great story how they got finished. Very cool, and Thank You for sharing the info and photos. Happy listening. 
I hate to say it, but now I think maybe I like my amp in ultralinear mode versus triode
It's a Cary V-12; it features a dozen EL34s and each pair has a switch in between them that configures that pair to either triode or ultralinear. In full triode Cary listed in the specs that it makes 50 wpc and in full ultralinear 100 wpc. For most of the twenty three years that I have owned this amp I have always felt that I preferred triode except for the occasions that I wanted to full out blast (it has literally been many years since I've felt the need to full out blast).
However, today I experimented with a couple of things in my system, and after listening to the same "Jazz Essentials" (compilation) red book CD a couple of times all the way through, the next thing I experimented with was switching to full ultralinear.
Maybe there was more "PRaT"? (Which is a term I am still not sure that I completely grasp.) Maybe . . . but what I do feel I noted for sure was that the imaging (particularly the imaging in the center) had more weight (meatier?) and was presented more forward, which I actually like.
I put a few more hours in (one more time with Jazz Essentials, Holly Cole/It Happened One Night, Dave's True Story/Sex Without Bodies, selected tracks from Rebecca Pigeon/The Raven and Once Blue/self titled and Norah Jones/Feels Like Home) after switching to ultralinear. (No booze during this session, just coffee.) 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.
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As far as the CAD-805RS, what Cary lists on their site under specs for feedback is "0 to 10 dB continuously variable control." |
Ralph makes a very good point about the percentage of screen taps and their relationship to the effectiveness of UL operation. In an earlier post I referred to the original "Musician's Amplifier," the first iteration of the the British Williamson amplifier proposed by Sarser and Sprinkle. It employed tubes and transformers more readily available on the American market. In 1952, when Hafler and Keroes published the first "ultralinear" Williamson, Sarser and Sprinkle noticed that the output transformer they chose for the "Musician's Amplifier," the Peerless S-265-Q, had primary taps that could act as 50% loads for the screens. They urged hobbyists to convert their "Musician's Amplifiers" to "ultralinear" operation by some simple changes to the circuit. In fact, while the 50% taps of the Peerless transformer are not *ideal*, they actually brought the output tubes just a hair closer to true triode operation while doubling the power output. Having built this amp myself, I can tell you that the result, despite its flaws, is quite beautiful. |
@immatthewj UL operation is feedback FWIW. To know how much you'd have to compare to pentode operation, which isn't an option... |
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