SET amp comparable to First Watt SIT 1?

Hi tmare,
You have a generous size listening room. You’re beginning to express some concerns. Why don’t you call Volti and talk with the builder himself? Parallel SET 300b, 845 or 211 SETs are options. Ask the builder his thoughts regarding OTL amplifiers as well. Discussion with him is a good starting point in my opinion.  Man oh man,  you have wonderful options. 
Charles

Hi Charles, thank you for another great advice. I really wanted to try 300B SET, so I know I should just go for it, at least for my first SET amp.

The reason why I have not contacted any manufactures on the list is I feel my candidates should be narrowed, and I don’t want to bother those people with my ignorant questions, also I don’t want to be biased by them. I’m planning to contact all manufactures when my candidates are finalized. and I’ll do it very soon. I have learned a lot from this thread already, and I’m much more confident what I was trying to do!

tmare,

PSET (Parallel Single-Ended Triode) topology with 300B tubes will do fine at the Volti- efficiency level, your listening habits and your room size. On nominal 100db/w/m speakers using for example 24w Audion PSET 300B Golden Dreams, at 1m you'll yield 112db at the 16th watt, and be quite usable into soft clipping by 115db. Now, you'll be sitting 3m away, and room surfaces, contents, etc. will reduce those actual and apparent levels at your listening position. If you routinely listened to full orchestral music at symphony hall crescendo live levels, you'd probably want a little more dynamic headroom in that listening space. But what you outlined indicates PSET 300B will be more than sufficient on a ~100db/w/m speaker.

You can drive keep most aspects of the 300B SET sound with a push-pull configuration. You'll gain some bass discipline but lose some nuance and tonal purity. Still good. But unless you find a four-tubes/ch p-p amp, the actual dynamic gain over PSET will be only about 3db.

A ~24w 845 SET amp will have the same measurable dynamics but will sound subjectively as having more "shove." For your stated preferences, I don't think the trade-off of 845 SET muscle for 300B PSET nuance and transparency is necessary.

For reference, on one of my systems, I use 24w on 101db/w/m speakers in a 21x14x 8.5 room, unbounded in two walls so he acoustic pressure dissipates into an open plan house. Seating position is 11.5' from the centerpoint between speakers.  I can cave my skull in with full on rock or symphonic music. You'll do fine.

I suggest against 211 amps. Tube choices are narrower, and you don't get the 845's shove nor the 300Bs nuance, tone and delicacy.

Phil

Charles,

The XLS variant of the 300B can be used in a straight 300B circuit, with normal 300B power output. Used in an amp configured to leverage the XLS tube's higher power potential, it takes on slightly different character but sounds impressive nevertheless. ~18w of premium 300B sound is nice. I'm right now able to compare Takatsuki, the EML 300B XLS and the KR 300B balloon in both Audion Golden Dream and the Luxman Anniversary MQ300 SET amp. The three tubes have roughly the same influences on both amps, but each amp imposes its signature on all three tubes as well. For me, the KR 300B prevails as the most objective and the most dynamic of the three tubes. The Takatsuki is very nice and is the most euphonic of the three but without bloat. The EML is the noisiest and the least consistent in octave-to-octave consistency, but these are not vast differences. Actionable but not vast.

I abandoned the EML tubes for chronic noise and reliability troubles. Perhaps you got better samples than me. The KRs take a licking and keep on ticking. I haven't enough time with Takasuki to judge but their build quality suggests great long-term stability and durability.

Phil

I owned the Audiopax 88 before I fully committed to Audion SET and PSET in my systems. The 88 is a beautiful sounding amp, though it is hardest to get deep bass to sound right. If you have speakers that have nothing usable below 40Hz or so, this isn't any problem.

The main contemporary problem with going Audiopax 88 is the sound quality of current production KT88 tubes. I was fortunate at the time to have an ample quantity of NOS British Gold Lion (Genelex) KT88s, as well as 1990s KR KT88s, ultra-screened from the old Tesla Vrovosic factory and relabeled KR. Both seriously improved the sound of the Apax 88 compared with any Russian production tetrodes. I let the Apaxes hang around awhile and pulled them out from time to time to try new tubes. They were pretty good with the Shuguang Treasure KT88, but still not up to NOS sonics.

So, that's what you have to consider going that route. Look at the price of remaining NOS Genelex/Gold Lion KT88s from the 1960s/70s or KRs from the 1990s, before making that commitment.

Phil