Atma-Sphere Class D… Amazing

Blushing, I was kinda jesting about point 1.  Testing equipment is of course more than sufficient, and Ralph's considered comment is important.

I agree on point 1. Measurements ought to be much more accurate, They are currently so useless and sloppy. Ought to go to to a at least few more decimal places.  We can agree on this.  Or not.

Its a matter of whether the person making the measurements knows what he is doing and whether the equipment needed is available. If you want to know how an amplifier will sound look at these things:

Distortion vs frequency; for best results it will not rise

Distortion spectra at 1 Watt

Distortion spectra at -6dB of full power. This particular measurement is where SETs fall on their collective faces as this is where the higher ordered harmonics show up, causing the amp to sound 'dynamic'.

In the case of the distortion spectra the lower orders must always be of enough amplitude to mask the higher orders regardless of the overall amount of distortion. THD as a measurement usually tells you almost nothing and is a good example of Daniel Von Recklinghausen's famous comment.

@mapman The ones that come to mind are:

 

1) the published measurements are not sufficient or accurate enough to be useful

2) The user does not know how to properly apply the measurements

3) The user simply does not care and prefers to rely on other means to make their decisions.

I agree on point 1. Measurements ought to be much more accurate, They are currently so useless and sloppy. Ought to go to to a at least few more decimal places. We can agree on this. Or not.

Point 2 - that the user does not know. Yep. Many words could be used to describe that person. I won’t dare.

Point 3. Cool.. You have perhaps defined an audiophile - more dollars than sense. Some manufacturers rely on this aspect. And they are reading this with a mix of joy and dread in their minds.

I’m curious why the Atmasphere Cl D amps are so low powered, compared to many others.   Most D’s seem to claim fairly high power. I guess the switching power supplies are not so constrained by size and weight limitations.  I had a D-Sonic, based on Pascal modules, that produced 800 watts into 8 ohms.  I went back to tubes, though.

@lloydc You just put your finger on the reason why, which is why bother if the amp won't sound like real music 😉 All that power doesn't do any good if the customer is going to go back to tubes (and lower power as a result...).

What are the cases in which measurements don’t matter?

I refer you to Daniel R. von Recklinghausen who was the chief engineer at HH Scott. He debunked, decades ago, the idea that measurements and the subjective experience are not intimately connected. 

@kuribo These two statements, one right after the other, seem contradictory:

I have provided an alternative view: subjective opinions carry no factual information. We must each listen for ourselves to find our own truth.

A lawyer might ask, in a court of law, 'which is it? Were you lying then or are you lying now?' 😁 I'm not suggesting that you're lying; I am suggesting that its impossible to be truly objective.

Subjective opinions can carry quite a bit of factual information. If all those opinions say the same thing and the people producing them are unaware of each other they carry quite a bit of weight. It seems to me that you've still not made the connection of how important measurements are to the subjective experience (and I see that all the time on the subjectivist side as well...). The rules of human hearing are the reason why; as I pointed out earlier all humans use the same perceptual rules. So if we can sort out what's important to the ear, then we can make the measurements to show if we've made progress. The former is the tricky bit!

You are aware no-one is going to beat Bruno's numbers any time soon. For that reason alone I really don't see what you are so concerned about what measurements we get. If that is the only concern just buy a Purifi and be done with it. The problem I see with that I already outlined.

Our goal was to make a class D amp that could allow anyone to enjoy the music and not worry about class D, tubes, class A or any of that stuff. In that regard we feel like we succeeded. A secondary concern is that tube production is waning due to a variety of events having nothing to do with the technology. IMO tube power amps are on borrowed time right now. The rest of it I've already explained.

http://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier

Anybody remember this review? Look at JA's measurements and his concluding comment, "Benchmark Media Systems' AHB2 is an extraordinary amplifier. Not only does its performance lie at the limits of what is possible for me to reliably test, it packs high power into a very small package, especially when used in bridged-mono mode. It is truly a high-resolution amplifier"

And so I ask any of you, even in October of 2015 was this really an "extraordinary amplifier". In the literal sense of the word, not ordinary, maybe. In the intended sense of the word as something superlative in terms of measurements, maybe. A "high resolution amplifier"? BS. This is where JA gets caught up as an engineer in sound floors aka distortion masking. He falsely equates resolution with bits (in his flawed DAC reviews and measurement methodology) and distortion sound levels. But my recollection is that the unwilling innocent suckers who bought the amp back in 2015-2017 based in the superlative review were by and large not thrilled. KR never could formulate reliable subjective listening impressions imho. And KR's tin ear notwithstanding, humans can not assess amplifier performance the way they can assess transducer performance-it  takes long periods of time before the attributes of an amp are reliably evident. 

I have no axe to grind. When I find out that there is a switching amp that thrills listeners whom I trust, I will be glad to audition one. History has shown that switching amps can ace measurement testing and bore the death out of the listener. No meat to the bones. No there there. 

It feels as if this whole issue of numbers and measurement is being extolled for the purpose of creating an argument.  The product designer has the right to publish whatever numbers they choose.  The customer has the right not to buy a product if numbers are important to them and there are no numbers to be found.

We all know that numbers often don't tell the story of how something will sound...I really like this statement from Floyd Toole because I think it captures the essence of why arguing about the validity of a product because you don't have the measurements is missing the mark:

"Audio is Art and there are aspects of the art for which we there are no scientific or technical measures yet we have little difficulty describing our reactions, positive and negative, when we hear....."

It would be of great benefit if everyone, before they post a comment, lead with whether they have heard the product they are commenting on...either in a store, at a show or in their home system.  I've heard the Atmasphere class d monos at a show and said good things about them.   

What are the cases in which measurements don’t matter?

The ones that come to mind are:

1) the published measurements are not sufficient or accurate enough to be useful

2) The user does not know how to properly apply the measurements

3) The user simply does not care and prefers to rely on other means to make their decisions.

as @mapman says, all measurements, reviews, user comments, seller and dealer claims are neither here nor there

they are all proxies, good bad or indifferent, for how any item will perform in your own system, whether it will please you, improve the sound of the music you hear

want to really know? have to pony up, try it, listen intently, compare rigorously fairly, be honest with yourself

nothing else matters, it is all to bait the hook, so to speak... arguing is just a waste of energy time and bandwidth

different fish here snap at different bait... no one really cares what anyone else will bite at

@mapman Measurements may or may not even matter in some cases.

What are the cases in which measurements don’t matter?

As many trade publications and review's by professionals and laymen have illustrated over the years.

Each will make that determination based on the factors that matter to them. Measurements may or may not even matter in some cases.

A well designed shootout among the leading or most popular class D amps would be very interesting, but getting conclusive results on such a highly subjective thing as how things "sound" is always problematic.

That leaves one to merely leverage both the two tools one has at their disposal to decide.....what they read including specs then always most importantly in the end what they hear.

Since everyone hears differently and also has unique goals and preferences, there is no pressure for anyone to agree with another.

At the same time, in lieu of objective measurements, no substantive conclusions regarding what is "best" or even "better" can ever be made. Each will make that determination based on the factors that matter to them. Measurements may or may not even matter in some cases.

@noske- that’s a good question- one would think the criteria would be either quantitative (specs and build-related) or qualitative (sound quality of various parameters), or both.  Not sure if that’s what you meant by your response 

@sutts if Ralph’s amps can hang with the performance of the Merrill 116’s, well now that would be something special..

Upon what criteria would an assessment be made as to their relative merits?

Is this thread confined to opinions on Atmasphere Class D only?  I have owned the top Class D offerings from Nuprime and Merrill, and if Ralph's amps can hang with the performance of the Merrill 116's, well now that would be something special...

Don't you wish Kenjit would chime in???  

@ricevs that ship has sailed. NAD, Apollo, Nord, not for me. AGD has 4 amplifiers. 
 

I decided to stay the course with an integrated amplifier of a hybrid design. Also keeping my Class A tube integrated.

@rsf507 "So are people going to start talking about the sound of the Atmasphere amps?"

Unfortunately that ship long passed once Mr measurement decided to take over the thread.

@jerryg123 

wow best you have.

I tailor my reply to the intelligence and mental age of the recipient Jerry. Thus, when addressing rude and poorly educated people, I am limited in my replies lest they confuse things like "reply" and "retort".  I imagine this is frustrating for you but imagine how others must feel when they have to explain things over and over...

jerryg123,

There is just one verson of AGD (assuming you heard the latest 2nd version) and only one version of the Atmas.......but there are tons of versions of the Purifi based amps and they all sound different from each other. So, which version (which discrete op amp, which regulators, dual mono or single power supply, quality of output jacks, etc.) by what company did you hear? As I mentioned before you can read on 10 Audio.com that my modded $1600 Purifi based VTV amp was preferred greatly to a NAD amp with a stock Purifi......

There is also a newer higher powered module from Purifi that has been for sale for some months now and it is supposed to sound better than the original......yet, they both are PURIFI modules.......again, what did you hear?

@jerryg123


A response is a retort. You are welcome.

re·tort¹

/rəˈtôrt/

Learn to pronounce

that tells me something about quality over quantity.

Actually your assumption is baseless as there is absolutely no proof whatsoever that lower power equates to higher quality. In fact, the AGD amp, the only GaN amp you mention that we actually have any performance data on, performs demonstrably worse than higher output class d amps from other manufacturers.

@lloydc  The AGD TEmpo di Gan is also 100W into 8 ohms, and the Audions are 85W into 8 ohms.  Alongside Ralph's monoblocks, also 100W into 8 ohms, that tells me something about quality over quantity.

So are people going to start talking about the sound of the Atmasphere amps?

Looks like someone is trying to erase the breadcrumbs so as to present an alternative narrative.

Great way to avoid the obvious distinction I made of you.
The old "i'm rubber and you're glue" response.

All the best,
Nonoise

@nonoise 

More name calling. Seems you aren't clever at all.

@nonoise 

Another negative attribute about zealots is they lack a sense of humor. 

Is name calling your usual response when people don't find anything funny about your sense of humor?

I’m curious why the Atmasphere Cl D amps are so low powered, compared to many others.   Most D’s seem to claim fairly high power. I guess the switching power supplies are not so constrained by size and weight limitations.  I had a D-Sonic, based on Pascal modules, that produced 800 watts into 8 ohms.  I went back to tubes, though.

Another negative attribute about zealots is they lack a sense of humor. 

@nonoise 

ignore what they refuse to listen to with their own ears.

Who has has refused to listen with their own ears or said not to trust one's own ears? All I have said is I refuse to listen with yours and other's ears. I trust mine just fine. More mischaracterization.

Looks like the disciples of the church of Bruno are laying it on pretty heavy. They decry those who cannot see with their own eyes yet ignore what they refuse to listen to with their own ears. Heresy!

All the best,
Nonoise

@facten

Nothing like high jacking someone’s thread.

If you try you will see the relevancy.

Why don’t you ASR guys start a whole other thread

Why don’t you?

Nothing like high jacking someone's thread. Why don't you ASR guys start a whole other thread

@noske 

 

I am very disappointed that the Gan guys have not taken an initiative on this. Gan is superior to silicon - so, prove it, as many others do in a variety of components and are sometimes subjected to criticism.  Everyone benefits.

110% agree. Exceptional claims require exceptional proof. Trust but verify, lol.

Here is an interesting take on the GaN device from the folks at Purifi:

Here is the opinion of the Purifi team on GaN as discussed in an interview:


Bruno: Well, with the sort of audio performance we’re getting I’d say that we’re asymptotically approaching “perfect”. One could argue that we passed the point of diminishing returns a few years ago already. I’m not saying that a next step won’t have any audible benefits, but in the grander scheme of things, the margin is shrinking.

Lars: That’s if you stick to audio performance alone. Otherwise we wouldn’t have bothered going to class D to begin with. You don’t do that for audio quality. You do that to get better efficiency, make the amp smaller and yadda. And then you get a new set of problems to fix, such as what it sounds like. And then there’s reliability, manufacturability and so on. I wouldn’t say that GaN is going to be the answer to those things, and neither is upping the switching frequency.

Bruno: Well for a given efficiency you could probably increase the switching rate, but if I’m going to shell out as much for a pair of FETs as what you’d normally pay for the whole amp, I’d rather benefit from that in terms of higher efficiency. Of course, not everyone is able to make that choice. I’ve spent my career honing control loops, most audio designers haven’t and so have to rely on simpler control loops. In that case, increasing the switching frequency is definitely helpful to reduce distortion.

Lars: We’re as fanatic about audio quality as anyone else, but because we’ve got feedback down to a T now we’re not forced to resort to higher switching frequencies.

Bruno: If we need to be geeky and I guess that the folks who are going to read this interview can handle that -eh Thomas?- lets grab the specs for the FET in our 400W Eigentakt module and its closest GaN equivalent. So that’s the FDP42AN15A0 (OnSemi) on our left and the EPC2033 on our right. Rdson: 36mOhm vs 7mOhm. Clear win for GaN here.

Lars: It’s also got a higher current rating (24A vs 48A) so if we want to be fair we should be scaling by about 2:1

Bruno: Oh erm well, that’s still a minor win for GaN because after scaling it’d come up at 14mOhm. Gate charge is of course magnificently low (30nC vs 6nC after scaling) so driver losses would be low and you can turn them on fast. GaN also has zero Qrr so you can do that if you want. But the main thing that sticks in my throat here is output capacitance. Our good old FDP42, which is from 2002 mind you, has an output capacitance at 100V of 70pF whereas the EPC device puts in a whopping half nanofarad (or 250 puff after scaling). That means your idle losses will go up, or you will have to increase dead time to allow the output inductor to recover the extra stored energy at its leisure. And isn’t it just idle losses that more or less determine real-life power consumption in full? And if power consumption isn’t something to care about, why not just stick with class A…?

Lars: And high dead time combined with high switching frequency sounds even less attractive. That just increases open-loop distortion.

Bruno: In applications like motor controllers and high density SMPS GaN and SiC devices are a breakthrough, mind you. It’s just that audio is this weird application where average power is very low and where dead time actually affects performance.

Lars: And GaN is going to mature so this picture is bound to shift at some point. Just not now.

Bruno: True. On the other hand, silicon is doing the same. More recent devices are getting frightfully close to GaN. Sadly they only come in SMD packages that require fairly expensive methods to get the heat out. Like most GaN devices. It looks terribly ancient, but the good old TO220 package is still a neat compromise in terms of performance for the price.

Lars: It’s just a game of tradeoffs. The fact that we’re using normal parts, and the reason why we chose to do so doesn’t make for a sexy story. We all like to believe in a magic bullet but when you’re an engineer you have to make choices based on tangible grounds. So the sexy story we’re trying to push about Eigentakt is that we think it’s a bloody clever design.



 

@kuribo At $20,000US, for a shiny aluminum box and a fake tube, with performance bettered by amps at 1/20th the price, I can find little to attract me for a listen.

Yes. It is imperative that blokes who are creating Gan amps provide a comprehensive and transparent independent audit of their measurements.

Failing that, it only promotes doubt as to anything that is claimed. Spot specifications are useful for off the rack retail gear.  Thanks maybe to Amir, intelligent audiophiles require a whole lot more before opening their wallet.

I am very disappointed that the Gan guys have not taken an initiative on this. Gan is superior to silicon - so, prove it, as many others do in a variety of components and are sometimes subjected to criticism. Everyone benefits.

I am not swayed by any philosophical art or flowery words. Just the facts, thankyou.

@holmz  My amps reside, with sufficient peace and dignity under the benevolent reign of King Charles III, in the country known as Australia.

Yeah @noske - which country or continent is that in which your amps reside?

Ralph did say, in and email, they are available in 230v, so I have to see if that is 50/60 Hz or solely 50Hz.

@holmz I am assuming your’s are 230v then, in addition to 50Hz?
So it would seem like you may be a long ways from Washington state in terms of shipping.
I’d kick in some $ to help with shipping if Amir has a 110-220v transformer, and if Ralph says that 60Hz is OK.

From a couple posts on AG and perhaps elsewhere, Ralph has said that he is working towards making his amps available to the wider community who have 50hz/240V power supply. I am not the odd exception, as Wiki shows here.

@aw-agd

@kuribo ...well...and that is my last comment on Audiogon, you may want to consider the fact that all amplifiers regardless the manufacturer/topology/technology will sound "differently" if one changes the load (i.e loudspeaker).

Well, that simply is not true. I have posted proof but for some unknown reason it was removed. An amp with a frequency response dependent on load will not only change character with a change in speakers but will change with the impedance changes of the speaker in use.

I’d do it myself, but I can’t because I am on 50Hz power.

@noske

Are there different transformers on the 5oHz model?
Or just a different tap point for 240v?

(A lot of newer gear is 50-60 Hz capable, so I am expecting the transformer may do both.)

I am assuming your’s are 230v then, in addition to 50Hz?
So it would seem like you may be a long ways from Washington state in terms of shipping.
I’d kick in some $ to help with shipping if Amir has a 110-220v transformer, and if Ralph says that 60Hz is OK.
​​​​​

Quite subjective. I call it a crush.

I won’t apologize for having an appreciation for excellence, regardless of the source.

I have been enjoying the Rogue Audio Pharaoh II for 2 weeks now, Tube pre section and Hypex N-Core power section. Agree with @mapman some great sounding stuff out there.