Calling all SET fans

11-17-15: Swampwalker
YW, Schubert. Two watts normally would make no discernible difference but that's a 33% increase, so maybe so. IIRC, Atmasphere has pointed out that very important to get adequate power w an SET amp because because their distortion rises very rapidly as power output goes up. I have no independent knowledge of these kind of technical issues, so if I'm not remembering correctly, my apologies.

You're remembering correctly, Michael. Atmasphere has said in a number of past threads that to get the best sonic performance from a SET amplifier it should not be asked to supply more than a small fraction of its rated power (something like 25% if **I** am remembering correctly), because of the progressively increasing amounts of distortion SETs produce at increasing power levels (and the progressively smaller amounts of distortion they produce at decreasing power levels).

However, neither the Almarro A205A nor the Coincident Dynamo is a SET, as the EL34 and EL84 are not triodes. And based on their power ratings and on the schematic and comments shown in this review of the Almarro A205A MkII I'm pretty certain that neither amp is even operating those tubes in the so-called triode mode. Therefore I'm not certain of the degree to which Ralph's point might be applicable to those particular amplifiers.

Regarding the difference in power capability, the Almarro A205A MkII is rated by the manufacturer at 5 watts, with the review indicating 4.8 watts. The difference between 4.8W and the 8W rating of the Dynamo is 2.2 db, not a great deal but perhaps enough to be significant on some recordings. As we all know, though, specs commonly don't tell the whole story when it comes to subjectively perceived power capability, with distortion characteristics, power supply robustness, and other factors being involved.

The one other comment I would offer at this point is that the multiple mentions on the second page of the Almarro review of hum, buzz, and the need for a cheater plug would definitely give me pause. I say that in part because in the photos of the unit there and elsewhere, and also based on the schematic shown in the review, it appears to me that the ground shells of the RCA input jacks, and hence the circuit ground of the unit, are probably connected directly to the chassis (although I can't tell with total certainty). Which would inherently create a susceptibility to ground loop issues, that may or may not materialize depending on the grounding configuration and other characteristics of the component(s) it is connected to.

Best regards,
-- Al

Schubert,
I owned the Almarro 205, in fact sold it here on Audiogon. Nice little amp, but watts aside the Coincident blows it out of the water in every meaningful parameter. How come on Audiogon a poster says he/she wants to spend no more than a thousand bucks and folks start recommending multiple thousand dollar speakers? This happens over and over, pet peeve of mine. Best, Rob

The main improvement of the Dynamo MK II is bigger and better transformers. Israel Blume(Coincident owner/founder) believes transformer quality is a "crucial" factor for tube amplifiers. He feels this MK II is a notable upgrade. Based on my dealings with him, I wouldn't doubt this at all.
I suspect this is a very stout and robust 8 watt amplifier with appropriate speaker matching.

Al, if I'm reading you right it would seem one should go right to a 3-4 K 300B amp or just forget about it ?

best,
Len

Len, no, I was not implying that. My mention of the fact that the Almarro amp and the Dynamo are not SET (Single Ended Triode) amplifiers was to make the point that for them to perform at their sonic best, whatever that best may be, it **might** be LESS necessary to run them at a small fraction of their rated power than in the case of a true SET.

Best regards,
-- Al