@twoleftears.....FYI, This has been brought to light, previously, on another thread, based on Class D...
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It’s good for it to have it’s own thread, new amp using the new GaN technology.
So long as the claims are kept real, and BS is not posted.
Wasn’t it this one or another (Nuprime) that claimed to have "super fast 500,000hz!!! switching frequency" which is just 500khz like most others?
BS No. 1 if it was.
GAN technology has great potential and many things in the future may benifit .you may have some that are not better then a very well implemented digital,or class AB amplifier ,it has much more to do withThe engineering design.
i will wait before jumping in .
the best new thing since sliced bread has been stated before !!
You are correct that many amps, but I will add not just class D, will not keep doubling their maximum power output from 4 to 2 ohms. Once the max current capability is reached, say at 4 ohms, then at 2 ohms the max power is only 50% of that at 4 ohms. 50% lower than that, or 25% at 1 ohm. This is particularly important for electrostatics whose impedance could be 1 ohm at HF. With some music that has high power HF percussion in triangles, snare drum and cymbal crashes, that is a big problem.
An example is my Bryston 2.5B SST2 amp, which puts out 135 watts at 8 ohms, only 180 at 4 ohms. The Bryston tech estimated only 100 at 2 ohms, and probably only 50 at 1 ohm. The larger Bryston 4B SST2 puts out 300 at 8 ohms, 500 at 4 ohms, and the tech estimated 600-700 at 2 ohms. Definitely better, but unfortunately all this doesn't correlate with the sound. Despite Bryston's official line that all the amps in the series with different outputs sound the same, my listening at home with the 2.5B SST2 shows much better transients and clarity vs the 4B SST2. With the 2.5, inferior power specs but better sound within its power limitations.
The larger Bryston 4B SST2 puts out 300 at 8 ohms, 500 at 4 ohms, and the tech estimated 600-700 at 2 ohms. Definitely better, but unfortunately all this doesn’t correlate with the sound.Yes you are correct Viber, I myself never liked the Bryston sound, and I put that down to just one of the things that I've never liked and that is that they use an excessive amount of global feedback, to get their specs.
I myself prefer much less feedback (so long as the amp still achieves good measurements) and also if the design allows the use of just local feedback (again so long as the amp has good measurements).
EG: my ME amps, Gryphon’s, Agostino, early Pass ect ect
Back to the 2 ohm thing, hey George.Yes MrD, and they are needed if one has some of the very best speakers around which dive to 2ohms or even lower, and you wish to get the very best out of them with no compromises.
Also note this difference between the two taken from a seminar on Mosfet V Bi-Polar (BJT), which to me gels with what I notice/hear.
"BJTs tend to have better, more linear gain characteristics…and can give you a lot higher voltage gain than MOSFETs.…They're also able to handle higher output currents…and have a lower output impedance.…That gives BJTs a huge advantage over MOSFETs…for building amplifier circuits…that need to provide a significant amount of output power…and or drive loads that have low input impedance.…MOSFETs are going to have a harder time…driving a low impedance load…because they have a higher output impedance.…"Cheers George
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.
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 2:38pmHow can you know "what to listen for"
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?
Of course there are different drive conditions and they are all addressable in changing over mosfets to bjt, you just choose not to believe it. 🤦♂️
And I'll post once again the pro's for going bi-polar
"BJTs tend to have better, more linear gain characteristics…and can give you a lot higher voltage gain than MOSFETs.…They're also able to handle higher output currents…and have a lower output impedance.…That gives BJTs a huge advantage over MOSFETs…for building amplifier circuits…that need to provide a significant amount of output power…and or drive loads that have low input impedance.…MOSFETs are going to have a harder time…driving a low impedance load…because they have a higher output impedance.…"
You can't just swap out the output FETs for the BJTs. There are a lot of other things that need to be addressed. It is not the same amplifier any more.
Again, do you know how to design amplifiers? I get the impression no or your replies would be more technical. Hence what you are posting is mainly heresay.
You can’t just swap out the output FETs for the BJTsPlease don’t say I said this sunshine, because I didn’t.
I said there’s a member who converts Mosfet amps into a BJT amps, and of course there’s more to it than just changing the output devices only a fool would think or suggest otherwise.
You can do it, if you had any half decent tech knowledge you would understand, end of story.
This is what you said "sunshine" and to my point, you are essentially making a different amp. The one who doesn't have any decent tech knowledge is you. I have designed many amplifiers, discreet and on integrated circuits, hence why what you post sounds so ridiculous to me. You can't simply change an output stage on a power stage between MOSFET and BJT. It don't work that way sunshine. Now if you had any tech knowledge you would know:
Actual "tech", not a cut and paste tech ....