2A3 Set power amp

Anyway I have purchased this amp made by Chris Barnett, with 2- 2a3 Sovtek, 2- 6F5GT National electronics and 1-jj rectifier tube. With my 88db B&W speakers I am astonished! This F-in thing sounds like a locomotive on the right track. Holy cow, so much for all the theories in this thread, most were dead wrong!

I do not believe it. There is no way! You are just saying that because you are going to sell the amp in the future. Chris Barnett is not an amp designer, he's a technician as far as I know. Are you in the Bay Area?

Sell the unit? Amandarine you are being plain idiotic. Yes the Bay Area

A single-ended 2a3 amp rated at 10-watts is REALLY pushing the tube hard. A friend who makes amps actually likes to push 2a3s and 45 pretty hard, but, then again, he has hundreds of tubes of those types and doesn't care if the tube does not live for a long time.

From my experience with 2a3 and 45 amps, the music that would most show off the power limitations of the amp would be large scale choral music, particularly if their is an emphasis on bass voices. For some reason (unknown to me) the amp will show obvious headroom limitation at surprisingly low subjective volume levels. But, for most popular music, which have limited dynamic range, low-powereed SETs can sound very good at reasonable sound levels. B&W speakers are not known to be an easy load, and 88 db/w is supposedly outside of the recommended efficiency, but if it works for you, GREAT.

One of the other things about good amplifiers, and SET amps in particular, is that one tends to be fully satisfied with the sound when playing at lower volume levels; if you have to crank it up for the music to come to life, the amp sucks.

The reason SETs have that amazing 'dynamic' character is all about how they make distortion. At very low levels, the distortion is unmeasureable. But at full power, the distortion is 10% and includes odd ordered harmonics, which are loudness cues to the human ear.

Music has lots of transients. So the distortion that has the odd orders only exists on the transients, not in between. This makes the transients seem louder to the human ear with respect to the rest of the music, hence that 'dynamic' quality; distortion physiologically interacting with our ears as 'dynamic'.

I prefer a system without loudness cues- that is to say it remains relaxed at *any* volume level, even where I have to shout to be heard by someone sitting right beside me. To describe dynamic range in a system like that I use the word 'impact'.

There are Class A2 techniques that will allow a pair of 2A3s to make 10 watts. The driver circuit really has to be designed right to make it happen without a lot of distortion. OTOH a pair of 2A3s in push pull will do about 15-16 watts easily.