I decided a couple weeks ago that as good as I think the c-j ET250S poweramp sounds with the S7s, I want an all-triode tubed amp. Triodephilia
indeed! Since I want some 25 - 50 Watts, don't want traditional push-pull operation, and can't tolerate, in my home theater, visually bright vacuumtubes such as the 845 and 805, I looked again at Atma-Sphere's Output-TransformerLess amps. I rejected the stereo S30 with 30WPC into 8 since 4-Ohm speakers were not recommended and landed on the 60-Watts-per-chassis-into-8* M-60s. The A-S amps are now in '3.3' versions which have their binding posts and RCA and XLR connectors on the rears and not fronts. I had purchased a used pair (in 3.1 version upgraded from Mk. IIs) maybe six years ago...
...hoping they'd drive the upper eight octaves of my Vandersteen 5As, but they didn't sound very good (but I don't remember exactly how), so out they went. (I'd hate to think
how many amp combinations I tried with the 5As until I bought a pair of McCormack DNA-750s.)
The Phoenix-metro area actually has a dealer, USA Tube Audio, that sells quite a bit of tubed equipment, and the owner made me a good deal on a new pair. So A-S is building them and I ought to see them in a couple weeks. Wish me luck. In anticipation of having these amps, I bought thru eBay a carton of 25** of the Russian Winged-C 6H13C (the US number is 6AS7G) output tubes for less than $8 each (!), and I retested my 15 Tung-Sol round plate 6SN7s. The M-60 uses four 'N7s (including one cathode follower) in the frontend. Because my system is set up for high gain in the preamp and low gain in the poweramps, I'll likely be using A-S's gain-reduction plugs in the V2 position, so that leaves a total of four TSRPs in the two amps. Hmm...maybe I can use two of the more-microfonic TSRPs in the CF positions...
Meanwhile, the c-j '250 still sounds excellent, so on with the music.
And I'm certainly not admitting to being too
obsessive about this kind of stuff, but I'm already investigating stainless-steel and brass blocks (with Herbies' energy-absorbing dots) to damp the middle of the chassis, as I was trying to do with the steel block between the tubes in the upper pic.
* and 45 into 4 and 80 into 16.
** My truly wonderful wife has called me Mr. Excess for good reason.