[Freo-1]

Sounds better? That's a subjective opinion that can neither be proven nor disproven. I prefer to stick to objective facts.

Bruno is committed to excellence. His work speaks for itself. He has the ability to use GaN if he wanted to, and he made his case in the interview above as to why he sees no advantage at present in clear and rationale terms. He addressed the thermal and speed advantages and explained the issues with them in a class d implementation.

"truly sounds open and transparent" is just more subjective opinion. The Purifi has much lower THD+N, a lower noise floor, and by any measure, a cleaner output, than this GaN amp. How much "clearer" can you ask for?

Seems you are stuck in the past with your perception of feedback. Maybe read Putzkey's papers on the subject.

Bruno is obviously a smart and accomplished engineer,  but no one person is the be all and end all.  I have read Bruno's paper on feedback,  and while it works for him,  it doesn't work for everybody.  The zero feedback GanFET Merrill amps get rave reviews.   The design approach from Primare A35.2 class d amp gets a Class A rating from stereophile.


Most of the folks I know who are into Audio don't much care for the Hypex sound.   Unless you have personally auditioned the Gan400, best to reserve judgment.

[Freo-1]

Great, no need to ever listen to 2 amps side by side anymore.  Just look at the measurements and pick which one measures better.  Makes life so much simpler.

But what happens if I buy a Purifi amp and 6 months down the road find I'm not listening to much music anymore, because my amp is making all my music sound like a constipated mess?  Which is pretty much my experience with all Class D amps (including the Hypex and Purifi amps)?  What then?  How will these measurements help me when that happens?

What he said. 


The Gan400 is the first class d amp I actually like.

[Tyson]

I have a theory that many people are actually quite sensitive to negative feedback.  Which is why they prefer tubes, because many tubes are inherently linear.  Solid state devices are not linear at all (with a few exceptions like the SIT amps).  Therefore to get SS amps to measure well, it requires feedback anywhere from 'a modest amount' to 'a shit-ton'.  For me, I'm fine with SS amps that use up-to-modest-levels of feedback.  But any more feedback that and it all just sounds so airless and mechanical.

Which is why I generally stick with tubes.  Since they are by nature linear amplification devices, less crap need to be done to the signal to get them to measure acceptably. 

People (especially engineers, I've noticed) seem to think that using feedback and other signal manipulations is a free ride and can be done without penalty in order to get prettier measurements at the end.   But they are so, so wrong.  At least IME and IMO and all that.

And this type of 'over-engineered' approach is not limited to amps.  You see the same type of thinking in speaker correction software.  Yes, you end up with better measurements, but all that signal manipulation just drains the life out of the music, again, IME and IMO.

[Freo-1]

I think Tyson is onto something here.  Most of my music listening is/has been with tube amps.  This Gan400 amplifier midrange does remind me some of SET tube amps.  The amp has a unique sound that combines attributes of both tubes and SS.   And yes,  I think the low feedback and speed of the GanFET is why.


I think tube fans may like it's sound. 

[goryu]

To each his own as I said, there is no debating subjective impressions and opinions based on such. Many love the distortion of tube amps, others prefer otherwise. There is no right or wrong. Many like hypex and Purifi and their lack of coloration. Others don't. If you wish to discuss the objective performance, that's something that can be rationally discussed. Otherwise, there is no point in arguing subjective impressions.

Bruno has made a good objective, counter argument against the superiority at present of GaN in class d amps. If you wish to continue to express your believe that in a class d amp they are somehow superior, then provide evidence that refutes Bruno's claims. If all you want to do is talk about your own subjective impressions, then it's best dropped.

[Freo-1]

To each his own as I said, there is no debating subjective impressions and opinions based on such. Many love the distortion of tube amps, others prefer otherwise. There is no right or wrong. Many like hypex and Purifi and their lack of coloration. Others don't. If you wish to discuss the objective performance, that's something that can be rationally discussed. Otherwise, there is no point in arguing subjective impressions.

Bruno has made a good objective, counter argument against the superiority at present of GaN in class d amps. If you wish to continue to express your believe that in a class d amp they are somehow superior, then provide evidence that refutes Bruno's claims. If all you want to do is talk about your own subjective impressions, then it's best dropped.

The link provided by gansystems.com does provide ample evidence of the GanFET performance over MOSFETS.   It's as valid as Bruno's white paper.  Check out the reviews on the Merrill as well.   


Again,  unless YOU have auditioned one of the GanFET amps, best to hold off on declarations.  I trust what I actually hear.  You should trust your own hearing as well. 

[goryu]

The link provided by gansystems.com does provide ample evidence of the GanFET performance over MOSFETS.   It's as valid as Bruno's white paper.  Check out the reviews on the Merrill as well.   


It doesn't address the issues raised by Bruno, never mind refute them.

I don't put much stock in subjective reviews.

[Tyson]

To each his own as I said, there is no debating subjective impressions and opinions based on such. Many love the distortion of tube amps, others prefer otherwise. There is no right or wrong. Many like hypex and Purifi and their lack of coloration. Others don't. If you wish to discuss the objective performance, that's something that can be rationally discussed. Otherwise, there is no point in arguing subjective impressions.

Bruno has made a good objective, counter argument against the superiority at present of GaN in class d amps. If you wish to continue to express your believe that in a class d amp they are somehow superior, then provide evidence that refutes Bruno's claims. If all you want to do is talk about your own subjective impressions, then it's best dropped.

But that's not true.  It's not true that Hypex and Purifi amps 'don't have a sound'.  Of course they have a sound.  All amps have a sound.  It just so happens that Hypex and Purifi have a sound that I don't like.  Despite what the measurements say. 

In fact, I'd argue that the front end process of getting the amps to measure well is exactly what's making them sound the way they do (constipated and closed off).  Great measurement's don't make an amp sound 'neutral'.  In fact in my experience, the manipulation of the signal actually makes those amps sound cold and unengaging.  Not in spite of the measurements, but because of them.

[Freo-1]

The link provided by gansystems.com does provide ample evidence of the GanFET performance over MOSFETS.   It's as valid as Bruno's white paper.  Check out the reviews on the Merrill as well.   


It doesn't address the issues raised by Bruno, never mind refute them.

I don't put much stock in subjective reviews.

You need to read it again.  Look at the turn off and on behaivor.  Bruno is not the only expert on this. 


As Tyson says, the amps can sound and un-engaging because of the heavy negative feedback to get the desired measurements.


If you haven't heard the Gan400 or the Merrill amps,  then you have no frame of reference to pass judgment.

[goryu]

Now you are simply making things up. What is "constipated and unengaging" and how does it correlate with the physical design of the amp? Do you have some metric? No, just opinion and speculation. This is simply religion versus science. No need to take this further into the weeds.

[Freo-1]

Now you are simply making things up. What is "constipated and unengaging" and how does it correlate with the physical design of the amp? Do you have some metric? No, just opinion and speculation. This is simply religion versus science. No need to take this further into the weeds.

You haven't answered if you actually heard any of the the GanFET amps in question.   No. It's not religion vs science.   It is a balance between measurements and listening to get optimal performance.  If one buys strictly on measurements,  then you can be missing out.  It's also closed minded.


Most all modern gear measures fairly well, YET, they sound different.   To only subscribe to only one set of engineering principals can be It's own religion. There are a lot of smart engineers,  and they each have their own approach to sound and design.  To ignore the obvious advantages of GanFET because one engineer you like doesn't use it (especially if you haven't heard it ) doesn't make a lot of sense.  Just because Bruno employs a ton of feedback and you like the sound doesn't mean everyone else agrees.  The zero or low feedback employed by other amps designs are often preferred sonically by audiophiles.


Before I heard the Gan400, didn't think it would sound that great,  but I was wrong.   I try gear a lot, and occasionally am surprised when I come across something that exceeds expectations. 

[Tyson]

Now you are simply making things up. What is "constipated and unengaging" and how does it correlate with the physical design of the amp? Do you have some metric? No, just opinion and speculation. This is simply religion versus science. No need to take this further into the weeds.

Hmm, I'm making observations based on direct experience and you're quoting a guru.  Indeed, one of us is engaging in 'religious' type behavior, and it's not me.

[Freo-1]

Hmm, I'm making observations based on direct experience and you're quoting a guru.  Indeed, one of us is engaging in 'religious' type behavior, and it's not me.

+1

[goryu]

I have listened to or owned a wide variety of class d amps over the years. I know from experience and engineering that an amp with varying frequency response with load is hit or miss at best. Most quality, modern class d amps have post filter feedback and have tamed the varying frequency response that plagued early class d amps. This amp is a 20 year old design with a modern GaN mosfet. Hardly state of the art.

I don't need to listen to this to know it's not something I want. I prefer well engineered, elegantly designed state of the art, not some fuel injected Pinto.

You can love it all you want. You can't argue on the engineering or measured performance because it is clearly substandard from any objective viewpoint. All you have is your own opinion. Which is fine, just don't try to engage in a rationale discussion when all you have to support your viewpoint is subjective opinion, not facts. I won't boor you with my opinion on how it sounds because it shouldn't matter to you, just like your opinion on how it sounds means nothing to me. Plenty of people raved about the early Tripath amps as well, others dismissed them. Load dependent. Where are they now?

No, I'm not quoting a guru, I'm quoting a leading expert and top designer of class d amps. Again, instead of insults why not refute his claims regarding GaN use in class d amps, feel free to offer your fact based rebuttal. Maybe you can produce some plots showing "constipation vs power" or "engagement vs frequency"...I won't hold my breath.

[Tyson]

I don't need to listen to this to know it's not something I want.

If you're unwilling to even listen, then literally nothing I can say will ever change your mind. 

Speaking for myself, I have only 1 requirement for an amp - that it actually sounds good.  Which the Hypex and Purifi amps fail at. 

[Freo-1]

So where are the measurements and circuit design with the Gan400?   Where did you obtain them?  The LSA amp has different specifications from the Gan400. 


Can't apply the ASR measurements to the Gan400. 


Sounds like another case of listening via meters vs actual usage.

[goryu]

If you're unwilling to even listen, then literally nothing I can say will ever change your mind. 

Speaking for myself, I have only 1 requirement for an amp - that it actually sounds good.  Which the Hypex and Purifi amps fail at. 

My listening has nothing to do with it. You are selling religion, I am speaking of science and engineering. Any amp will have its fans and detractors. That's only to be expected. This amp, with its varying frequency response, will be all over the place, depending on load. I find that poor engineering in 2022 and unacceptable. If you like it, good for you. Hypex and Purifi amps may not please you, but clearly they please a great many people. I have no doubt they will be around long after this 1990's class d amp with a marketing ploy mosfet is history.

Enjoy!

[goryu]

So where are the measurements and circuit design with the Gan400?   Where did you obtain them?  The LSA amp has different specifications from the Gan400.


Sounds like another case of listening via meters vs actual usage.

Same class d module used in both it seems...the 90's called- they want they class d amp back...

Here's a subjective review for you from another audio forum:

"If turns out that both the LSA Voyager GAN 350 and the Peachtree GaN400 amplifiers use the same modules from/designed by Elegant Audio Solutions. While both have what seems to be different power supplies, the main amplifier board looks identical. The board uses the GaN Systems HEMT and Elegant Audio Systems is listed as one of their partners. If you go to the GaN Systems website, they have reference boards and detailed information about their reference designs. If you look at the pictures in the reference designs, you will see that those also are from Elegant Audio Solutions.

I had a chance to listen to the Peachtree GaN400 version of this and it at least worked as you would expect out of the box. I (subjectively) had the opportunity to compare the NAD 2200 (upgraded components), GaN400, McIntosh MA252 and the Purifi Eval1. Being an engineer myself and a believer in numbers I have to say that I have bought several components including the NAD 2200 after seeing the great measurements on ASR and was firmly in the camp of that it would be impossible for me to hear a difference in real life with any of these components. I have to say that I was wrong. In my listening tests I found that consistently of the 4, I picked the NAD 2200 as the worst sounding and the Purifi Eval1 as the best sounding with the GaN400/MA252 somewhere in between consistently. My general observations are:

1. The Purifi amp has a level of clarity, detail and high frequency response that I have never heard on any other amplifier including the Benchmark ABH2. The LSA wasn't bad, but didn't really compare to the Purifi. At about 1/3rd the price, you could buy 3 of the Eval1's for the price of the LSA.

2. You need speakers that can resolve the detail. I found that you need speakers that can resolve the details such as Magnepan LRS, Magico S5 vs. a couple of other speakers that I tried that I just couldn't hear any differences.

Last week a couple of friends and I did some blind testing using the Purifi, MA252 and the ABH2 connected to Topping D90SE and Magico S5MKII. One of these days I will post the results of what we did and how, but if you were going to buy something and you aren't able to try out a bunch of amplifiers, buy the Purifi, it is unlike any other amplifier that I have heard and it is the cheapest of the bunch.

Corrected: MA252 not MC252."

[Freo-1]

My listening has nothing to do with it. You are selling religion, I am speaking of science and engineering. Any amp will have its fans and detractors. That's only to be expected. This amp, with its varying frequency response, will be all over the place, depending on load. I find that poor engineering in 2022 and unacceptable. If you like it, good for you. Hypex and Purifi amps may not please you, but clearly they please a great many people. I have no doubt they will be around long after this 1990's class d amp with a marketing ploy mosfet is history.

Enjoy!

No, you are selling science according to your personal opinions. 


IF you have actual measurements from the Gan 400, by all means,  post them.  The ASR measurements for the LSA don't count.   The GanFET does have better behavior over MOSFETS.   This means it needs less feedback.   It also has better thermal behavior.


I've heard two other Class D amps I did thought sounded good.  One was the Primare approach,  and the other was Devialet,  which is Class A voltage and class d current.


Unlike some,  I would not pass judgment on any amp I haven't heard.  Since I haven't heard the Purifi,  I pass no judgment on it. Just didn't care for the sound of the Hypex. 


Lastly,  disagreement is not insulting.

[goryu]

The two use the same board- they have the same lack of post filter feedback. They are thus both load dependent. This isn't an opinion, it's fact based on their design. All modern class d amps I am familiar with have evolved and have flat frequency response with load because they use a feedback arrangement that puts the output filter (the source of most of the distortion in a class d amp) inside the loop. Do some homework.

No disagreement is not insulting. Calling a well respected and accomplished engineer like Putzkeys a guru is, in my opinion.