new GAN amplifier

@twoleftears.....FYI, This has been brought to light, previously, on another thread, based on Class D...

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.

Cheers George

I mentioned that am expecting one in my Life with Ric Schultz EVS 1200 thread


I will start a new thread when I do

The doubling of output from 8 to 4 ohms suggests a good power supply.  Good for starters.

The doubling of output from 8 to 4 ohms suggests a good power supply.

Most Class-D can double from 8 to 4ohms
It's when test bench measured independently, from 4ohms to 2ohms is where they usually *** themselves, many actually go backwards instead of doubling or even increasing.

Cheers George 

Back to the 2 ohm thing, hey George.

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 !!

George,
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.

We seem to be freely mixing new solid state technology (GaN), output impedance,and power supply current delivery .
A bit more structured logic would help.

All 8 of my current class d amps are rock solid and not going anywhere but I feel good knowing that as time goes on there are more and more great sounding and cost effective options out there.

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
https://ibb.co/kGJMXcr
https://ibb.co/0hTPp6f
https://ibb.co/N94rSTt

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.


Cheers George

George,
Even though Pass may have less feedback than Bryston, I hate the euphonic sound of Pass.  There are many more factors determining the sound than the amount of feedback.  

Many (me included) just don't like Mosfet sound. 
 Listen to some older Threshold Pass amps that used bi-polars, you'll change your mind.

Cheers George

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

I am going to go out on a limb and say you wouldn't know without being told if the amplifier had FETs, BJTs, etc.   Topology is going to make far more difference to the sound.

Maybe, if those listeners don't know what to listen for.
But for those same listeners short term living with each amp, listening to many albums over a few days you eventually would pick it, especially if the speakers are hard to drive.

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.

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?

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 BJTs

Please 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:

• Typical output stages have 0 voltage gain so quoting in this case that they have higher voltage gain is silly.
• In an amplifier, output current is mainly a function of thermal limitations. I can cheaply buy a 100A MOSFET, more than enough for almost any power level so to say a BJT can handle higher current is just wrong. That has not been true for decades.
• Output impedance is a function of device and circuit, not just the device so making a claim a BJT has lower output impedance is specious. You can try to make the claim there is less difference in base/emitter voltage compared to gate/drain voltage over loading, but higher biasing of the output stage with modern FETs can negate that advantage. As well a BJT requires a very high current to drive it and that current gain is variable w.r.t. output current leading to distortion inducing mechanisms elsewhere in the amplifier that a FET amp may not experience ..... And also why you cannot simply swap the output stage! ...and have it work properly.

Actual "tech", not a cut and paste tech ....

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.

IMHO, Gfi is making a lot of sense here

Still awaiting my Voyager (GaN), but still loving my EVS 1200 (class D)

Great pricepoint

Excellent cust svc

@atdavid is correct. By the time anyone had modified a MOSFET amp to run with BJTs it would be an entirely different amplifier. There simply would be no way to compare 'before' and 'after'. Its highly unlikely that anyone ever did a mod like this unless the amp was gutting for its chassis and power supply.

Its highly unlikely that anyone ever did a mod like this unless the amp was gutting for its chassis and power supply.

Include to the the complete chassis, transformer/s, power supply, the heatsinks and input stage to that, which is around 80% of the amp.

What’s left is the driver/output stage and bias mods. So yes I see it as doable, as he said he’s doing, but I think it would be limited to T03 case substitutions, otherwise would get messy.
And yes two different amps one Mosfet the other BJT using the same 80% above components.

Output stage, the stage before the output stage, hopefully the feedback network, the bias circuitry for the output stage ..... It's a different amplifier.

Can you even buy TO3 transistors any more? (TO3, as opposed to TO3P which is a different beast). I think with the exception of MIL they have all been long obsoleted.

It's a different amplifier.

Sorry, same amp with different output/driver stage and bias change.That allows one to directly compare same amount of Mosfet devices to the same amount of BJT devices

Can you even buy TO3 transistors any more

Of course you can don't be an *****, and they're still cheap and plentiful,  just look around.https://www.ebay.com/itm/1pairs-OR-2PCS-Transistor-MOTOROLA-TO-3-MJ15003-MJ15004-100-Genuine-Origina...

End of story, no more on this as it's not about the title "new GaN Amplifiers" 

On the TO3, I mean that quite seriously. I can’t remember the last time I saw anyone use a TO3 in a production design. Your idea of plentiful and cheap is likely different from mine. I don’t buy components off EBay unless I am finding something obsolete. You can find the odd TO-3 in stock at stocking distributors, but they are a rarity these days and legacy devices.


If you change the output stage, bias circuit, and the drive circuitry before the output stage, which means 2 stages of what is likely a 4-6 stage amplifier (and likely feedback to account for different bandwidths), then it is not the same amplifier any more. You can’t change 33-50% of an amplifier and say you are just comparing the output devices.  Yes end of story. Your claim that this allows you to simply compare output devices is not true.

Give it a rest sunshine it’s doable, and not as complicated as you make out, your full of it, I would estimate a days or less work for a good tech, with the components and schematic of the donor mosfet amp at hand.

Now lets get back onto the OP’s topic.

And it’s a different amplifier when done, and not indicative of a comparison of two sets of output devices .... sunshine. Yes, lets get back to the OPs topic which you side-tracked ....

georgehifi6,190 posts11-15-2019 2:13pmMany (me included) just don’t like Mosfet sound.
Listen to some older Threshold Pass amps that used bi-polars, you’ll change your mind.

Cheers George

Post removed Nov 19, 2019

That was too strong for him could have caused him mental damage, it wasn’t going to help.

Yes, lets get back to the OPs topic which you side-tracked ...

 🤦‍♂️ whatever

I had this debate with George on another thread, that concerned the purchase of an older Rowland amplifier. I have owned all kinds of amplifiers. Those that use mosfets, and those that use bjt devices. I am currently running a pair of mono blocks, designed by Hafler, that were made for the movie / cinema industry, that are, to my ears, amazing. They are biased in class A, run extremely hot, use Hitachi mosfets, and drive my Lascalas, wonderfully, and easily......If it sounds good to you, so be it.....also, when it comes to recordings, doesn't  the microphones, cabling, recorders, mixing consoles, eq boards, compression boards, etc., all add to the final sound we are listening to ? I also believe, hard to drive speakers, are ridiculous.....have owned some, and, never again....

I also believe, hard to drive speakers, are ridiculous

Your opinion Mr D.
This is where we differ big time, I would not call Klipch Lascala speakers or Hafler amps state of the art audio devices,having owned the Lascala’s and repaired a couple of Haflers.

I’ve found the most "uncolored full range" speakers, usually to be among the very hardest to drive, due to all the work that goes into them to make them full range, uncolored, and using the drivers in their most linear range with complex xover do do it. This all adds up to an inefficient speaker, with very low impedance dips and nasty - phase angles.  

Cheers George

George, I have a challenge for you. Take your most uncolored full range speakers, ones that are hard to drive, choose your amplifier ( s ),.....now, take a reasonbly priced mixer, such as a Peavey PV 6BT mixer ( my buddy has one ).......connect it into this system......now, using a great mic, such as the world renowned Neumann U87, and, with a Stevie Ray Vaughn Fender Strat ( of which I love the sound )......I will be the singer, my buddy will play the guitar, and let us see ( hear ) what " this " system can do. Maybe, add a drum machine.....You can choose your own musicians........,

This in my signal path, no chance, not ever!
https://assets.peavey.com/images/large/118741_33943.jpg

Cheers George

What a cop out george..." this " system of yours, would not be able to handle the dynamics of live musical instruments....but you likely know that. I could find a state of the art mixer, if you would like, and we can try it again........BTW, you should look up the mic and guitar, as they are the source, and would make a bigger difference, in my test, than a superior mixer......Enjoy ! MrD.

See that’s the difference between us, you can handle the Klipsch Lascala’s horn and box coloration’s, and no deep bass, I can’t.
I want to get the signal from the source to the speakers the purest way possible full range with no limitations on wattage or current or frequency, because the speakers also have to be least colored most dynamic you can get, unfortunately that usually means they’re hard to drive.
And to putting that "Peavy Thing" in the signal path goes against all of this.
Cheers George

george, 1st, you have not heard my Lascalas, or any Lascalas for that matter, that have been properly modified. 2nd, I do have an excellent pair of bass modules to take care of the last octave, and, work, very seamlessly, and coherently, with the Klipsch Lascala dog houses ( the horn loaded woofers ). I really do not think, george, you have spent much time, around live, unamplified music. If you did, you would not argue about everything, with everyone. Your main criteria, and experience, with listening, is with recorded music, and hifi gear. And, you seemed to dodge my point above, again. So, without further ado, we agree, to disagree. Cheers, and Enjoy ! MrD. BTW, I am done with this particular conversation...........you are like, the energizer bunny....you are number one, on all of the "Gon, as bantering goes. 

I am done with this particular conversation

Ditto, there’s no reasoning with Klipsch Lascala owners, beaten only by JBL owners. 
Remember I owned them, and the Forte, the Forte were a far more musical speaker, but still colored and midfi.

because the speakers also have to be least colored most dynamic you can get, unfortunately that usually means they’re hard to drive.

This statement is false. Less efficient speakers also tend to be less dynamic due to voice coil heating. A secondary reason is the harder any amplifier is made to work to drive a speaker, the more distortion it makes- which is audible as reduced detail and increased harshness.

Pot, meet kettle ....

georgehifi6,196 posts11-18-2019 4:17pm

Now lets get back onto the OP’s topic.

Less efficient speakers also tend to be less dynamic due to voice coil heating.

This statement is more false, as the drivers are built far more exactly to meet their operational parameters

A secondary reason is the harder any amplifier is made to work to drive a speaker, the more distortion it makes

This statement is even more false, as the purpose built amps that can double their wattage’s down to 2ohm and that can drive them and have far less distortions than your OTL's, you are just in product protection mode because OTL’s can only drive certain speakers without distorting and those speakers usually have far more coloration/distortions as well. 

atmasphere7,771 posts09-18-2019 6:50amOur OTLs do a nice job on the Alexia

This one statement among others, shows just that your not of this planet anymore.
To say your OTL’s can drive the Wilson Alexia!!!!. is just so ?? words fail me.
One of the hardest speakers ever to drive correctly, yet one of the most accurate that I and others have ever heard, when driven with amps with big current that can do them justice.

Not sure what all this has to do with a new GAN amplifier, but the Wilson Alexia, at least the current model does not seem that hard to drive. Even the older ones only drop to 2ohms.


Can you put some more details into your hypothesis that being able to double power into 2 ohms is a guarantee of "quality". I can see reasons why it could be, but not a guarantee, just as the way I can see why power limitations at 2 ohm are not a guarantee of a lack of quality.

Back to Class-D, there is of course no inherent reason why a Class-D can't work at 2 ohms, or less. If you want best operation with low impedance loads, you would want to optimize for that, but then that is true for a linear amplifier as well.



https://www.stereophile.com/content/wilson-audio-specialties-alexia-series-2-loudspeaker-measurement...

https://www.stereophile.com/content/wilson-audio-specialties-alexia-loudspeaker-measurements