SET amp comparable to First Watt SIT 1?

I don’t want to bother those people with my ignorant questions,

@tmare, ignorant questions are the best ones! Never, ever worry if you are bothering the manufacturer by asking them; that should be part of why they are there!! Otherwise you might want to rethink how much support you're going to get.

I have owned OTL amps and like many of their characteristics, but I've never heard one, especially using massed output tubes, that has the sheer transparency, speed, holistic tone and spatial precision of Audion SET overall, and especially the Golden Dream monoblocks

Funny- my experience has been the opposite. Our amps have a risetime in the output section of 600V/mS, where the typical SET might be about 10V/mS. So its not only audible but measurable. Usually that's a pretty good indication that its actually real. In addition to the speed, our amps have more bandwidth as well.

Now what is going on with a specific amp on a specific speaker might really affect the outcome of your perceptions (for example a low impedance at high frequencies that one amp can drive while the other can't might make that latter seem slower even though its not). So its a good idea when doing comparisons to make sure that both amps, whatever they are, are in proper operating condition and are also a reasonable match for the speaker being used (that is, if you really want to find out what the differences are between the amps being compared).

Yup, true. I've used OTL and SET on a very wide variety of speakers under optimal conditions for both amps. I'll put my statement cited in further perspective:

40, 30, 20 years ago, I would have (and did) recommend and own OTL tube amps for maximum transparency, speed and musicality, used with appropriate speakers, including over all the SET amps I'd gotten my hands on up to 1999. That's when I first happened upon an Audion SET 300B amp. And then further put original KR Enterprises 300Bs and well-chosen NOS input and driver tubes in it. With the emergence of objective high efficiency speakers (ala Zu) in the 2000s, the higher power of OTL became less necessary.

The Atmasphere amps are certainly transparent and fast, and I don't dispute the rise time measurements you site for them. But Audion SET amps are uniquely fast and transparent examples of that topology and I hear them as a notch above OTL.

Phil

A friend of mine is a happy owner of the Atmasphere MA-1 amplifier and MP-1 preamplifier. He has efficient and easily driven speakers ( so amplifier power wasn't a determining factor). We compared his amp with my 300b SET and no other system component was changed. Both of these amplifiers were "very" transparent, open, fast and clear. Both had exceptional staging, imaging focus and music flow/pace. The SET playing the same recordings was fuller in tone and body with an increased sense of presence. It presented harmonic information that was more vibrant and a bit richer.The Atmasphere was relatively more towards a leaner sound (but by no means pale,sterile or flat). Different people will prefer one or the other. I happen to be drawn more to the fuller instrument sound and nuance of the SET.  Both amplifiers are very fine but speak with their own sonic character.
Charles

tmare - fwiw, I used the SIT-2 and SIT-1 in a large space like yourself and like to even crank electronica at times. I would recommend more wattage like 213Cobra suggests.

I think if you are considering SS, you might look at Pass XA-30.8 which you can audition from Reno Hifi. There also is a pair of Sophia Electric 845 amps on this site which can get you into good SET relatively cheaply.

@charles1dad  I'm good with that- that's how I would describe it too. You expect an SET to sound fuller as it has more 2nd harmonic distortion where the MA-1 really does not have much at all. I think that if you had a sound pressure level meter in the room, you would have found that although you were careful to match the volume of both amps by ear, that in reality the MA-1 was actually playing at a higher level.

The leaner sound our amps often have is simply that they make less distortion (most of it being the 3rd harmonic, at about or slightly less than an SET will make at the same percentage of power level with respect to full output).

When designing any kind of amp its all about the distortion it makes as to how it will be regarded. For example solid state amps have a lot less distortion but what they do have tends to be higher ordered harmonics which the ear translates as 'bright' and 'hard'; for a solid state designer its the 7th harmonic that is the one to be avoided if possible. I figure those are the drop dead harmonics to avoid if you plan to play the system for hours and hours on end. That way you won't get fatigued.