new GAN amplifier

How can you know "what to listen for" wrt transistor type when you don't even know the underlying amplifier topology and distortion mechanisms, intentional voicing, damping versus frequency, bandwidth, etc.   You simply can't.  You can't take something you heard on a limited set of products and apply that to all products.

How can you know "what to listen for"

There’s a post a member put up a couple of weeks ago (go find it), who does mods for his customers, where he takes a Mosfet amp removes the complimentary N/P channel Mosfet output stage and replaces it with complimentary NPN/PNP Bi-Polar (BJT), and he and his customers say it all in their description of the sound change.

That’s why I said if you live with the two for a while you will hear the difference.

If you read what was said at the seminar, you can apply that to what you might hear, again especially on the harder to drive speakers.

I hear Mosfets into my hard to drive speakers as "polite" but a bit of a "yawn" that lack that punch, drive, boogie factor, and an openness that BJT’s have that can also be detrimental with bad recordings.
Some call it "Mosfet Mist" other call it "Tube’ish" I think maybe it’s because they aren’t as linear as BJT’s just like tubes with with 2HD as outlined in the seminar.

Cheers George

This, what you wrote below, I cannot just accept on the face as factual. The drive requirements, biasing, temperature compensation, bandwidth vs. drive, etc. are so significantly different between a BJT pair and MOSFET pair, that unless you essentially modified the whole amplifier, you could not do this and at which point you essentially have two different amplifiers and at that point, any comparison has lost all meaning.

georgehifi6,173 posts11-16-2019 2:38pm

How can you know "what to listen for"

There’s a post a member put up a couple of weeks ago (go find it), who does mods for his customers, where he takes a Mosfet amp removes the complimentary N/P channel Mosfet output stage and replaces it with complimentary NPN/PNP Bi-Polar (BJT), and he and his customers say it all in their description of the sound change.

what you wrote below, I cannot just accept on the face as factual.

That's your opinion, it is, and if your are a tech you'll know that it's very possible to do this to the driver/output stage.
Cheers George

No that is not an opinion that is a experience. The drive requirements for a set of bipolar transistors and a set of mosfets is much much different. Add in different biasing requirements, different thermal compensation, different bandwidths for a given drive circuit, etc. If you change the two you don’t have the same amplifier anymore. Do you design amplifiers or are you just repeating others?