SET vs OTL

Aarif,

I've owned both types of amplifier and, before you can describe either, you have to bear in mind that the sound of these amps are entirely speaker match dependent. So, assuming that we've got the right speaker match, I'll paraphrase Ralph;

SETs amps tend toward candlelight (warm & romantic)

OTLs amps tend toward sunlight (neutral & revealing)

IME

Marty

Aarif, removing distortion never causes an amplifier to have fake neutrality.

OTLs have an economy of scale- the bigger you make them, the more efficient they can run. A big OTL that can make 200 watts will very likely be comfortable on 4 ohms, some smaller ones that make 150 watts might be able to do that also. A 30-watt OTL will not like 4 ohms much at all.

IOW the smaller you make the OTL, the higher you will want the load impedance to be. Many OTL headphone amps are designed for 32 ohms or more, plus they do not have to make more than 0.2 watts. Headphone amplifiers also are a special case because most headphones are designed to operate with amplifiers that have a much higher output impedance than their own impedance.

Without more information about your speakers, it would be hard to make a certain case for either amplifier technology, and we have to include your listening preferences somehow too. Although I have heard very good things about the Graaf, I've not actually heard it, so the following is my opinion only. I think it would have a chance at being a more neutral, musical presentation if the speaker impedance is linear and 7 or 8 ohms at least. I don't agree with some of the tube choices in that amplifier, as I feel that they tend to make the amp sound brighter, so I do have reservations at the same time.

In the end, like so many other things in audio, you will have to audition to know for sure. Remember- its all supposed to be fun :)

Is it possible that the reason SET tends to sound harmonically richer than a push-pull OTL amp is that the latter has a phase splitter that causes information to be lost?

After all, when we speak of 'SET vs OTL', what we mean is single-ended transformer-coupled vs. push-pull direct-coupled.

Ralph, I like your amps and have a lot of respect for you & your company, but to say that the <1% of 2nd-order harmonic added by a SET at moderate volumes on appropriate speakers, when studies have shown up to three times that amount is not audible, just doesn't make sense to me.

A good SET just gives me more 'chills of realism' than an OTL push-pull amp.

Mind you, I'm no musician and don't have perfect pitch.

I meant to say "but to say that the <1% of 2nd-order harmonic added by a SET at moderate volumes on appropriate speakers *is what causes this harmonic richness*, when studies have shown up to three times that amount is not audible, just doesn't make sense to me."

Atmasphere,
Paul's last question is one I share - does the phase splitter itself ever create
distortion issues (i.e. something like 'hysteresis') when the signal is re-
merged?

Second, I have always had questions about 'parallel' SET circuits, and
wondered whether or not one could, with the right tube, do a single-ended
OTL circuit which was 'accordion amplifier' circuit style (and if done right, use
more than two tubes). I expect this will be revealed to be a stupid question as
I am surely overlooking something obvious, but... I'll ask anyway... :^)

Has anyone ever used/made/heard a singled-ended 'accordion amplifier'
circuit? I read about this a while ago (TubeCAD Journal) but have never seen
anyone talk about one, though my gut is that this exists under another name
and I do not know about it.