Today I picked up my Atma-Sphere Class D Amps. These aren’t broken in yet. And they are simply amazing. I’ve listen to a lot of High End Class D. Some that cost many times what Atma-Sphere Class D costs. I wasn’t a fan of any of them. But these amps are amazing. I really expected to hate them. So my expectations were low. The Details are of what I’ve never heard from any other amps. They are extremely neutral. To say the realism is is extremely good is a gross understatement. They are so transparent it’s scary. These amps just grab you and suck you into the music. After I live with them some and get them broken in. And do some comparisons to some other high end Amps Solid State, Tubes and Class D’s, also in other systems I’ll do a more comprehensive review. But for now, these are simply amazing amps.. Congrats to Ralph and his team. You guys nailed on these.
So here is a question, @kuribohas gone hard at the aforementioned amplifiers built by Ralph and his fine company, question is have you an opinion (yep regret that now) on the AGD GaN mono blocks?
If one can get past the aethetics/gimmickry, this is what a reviewer had to say about the $20,000US version:
"output impedance [dashed trace, see Graph, above] rises steeply at HF, as does distortion, while the frequency response varies with speaker load impedance [unloaded/8/4/2/1ohm = grey/black/red/blue/green traces]. Put simply, if the impedance trend of your speakers rises in the treble then the Gran Vivace will likely sound brighter, and vice-versa.."
"a marked increase in THD into loads below 4ohm – typically >0.1% from 1-100W/2ohm versus 0.002-0.08% into 8ohm. Under continuous conditions, distortion increases from 0.004%/1W, 0.005%/10W and 0.09%/100W (all at 1kHz). Distortion also increases with frequency [see Graph 2, below] from 0.005%/1kHz to 0.07%/10kHz and 0.3%/20kHz (all at 10W/8ohm) in line with the response of the reactive output filter network."
The switching frequency is 800Khz, a bit higher than what most using silicon mosfets use (600Khz or so) but not really high enough to take meaningful advantage of the benefits of GaN mosfets. The Techniques GaN, for comparison, switches at 1.5mhz.
Load dependency is a non-starter for me. I wouldn’t call the performance "state of the art".
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.
You are welcome anytime to visit us at the next Audio Show and listen to our amps and then corroborate or revisit your assumptions. However as a matter of curiosity, is there a reason why in your peculiar selective cut&paste exercise you decided to omitt what in the same article the reviewer wrote about the sonic qualities and his personal experience about the sound?
However as a matter of curiosity, is there a reason why in your peculiar selective cut&paste exercise you decided to omitt what in the same article the reviewer wrote about the sonic qualities and his personal experience about the sound?
I don't put any value in subjective opinions of third parties of audio equipment, especially when the associated equipment and listening environment are different than my own. In this case, the load dependent frequency response alone tells me that this amp will sound differently depending on the speakers used- all the more reason to disregard the subjective impressions.
@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). That is why it is better to have a direct use of the auditive sense we humans are equipped with, to chose what one likes more.
Finally, for all my audiophile colleagues that still prefer reading numbers instead of listening music, I would like to remember what Galileo said "...eppur si muove.."; a very profound statemwnt despite the grave situation in which he was forced in. However, for all you, next time you may pass-by Firenze, I suggest to visit the Galilean Museum and ponder a bit when in front of the glass ball containg Galileo's hand (really, his right hand) and decipher what message he left to the posterity by using the effect of the rigor-mortis of his hand. All the best.
"While noise and spuriae are low in this design the ’traditional’ bridged Class D architecture and inductive output filtering retain some drawbacks – output impedance [dashed trace, see Graph, above] rises steeply at HF, as does distortion, while the frequency response varies with speaker load impedance [unloaded/8/4/2/1ohm = grey/black/red/blue/green traces]. Put simply, if the impedance trend of your speakers rises in the treble then the Gran Vivace will likely sound brighter, and vice-versa."
Please notice how your amp has a frequency response which varies with load, unlike the Purifi, which is ruler flat.
Your amp will change character even without changing the loudspeaker!
Of course one must at last choose on one’s opinion of the sound, but for me, I expect an amp at this price range to meet certain objective criteria first and load independence is a important to me as I don’t want an amp with a frequency response/character that varies with changing speaker impedance. This issue was resolved 25 years ago or more in class d design.
Fwiw I am a long time Class D owner and fan ( well documented here).
I decided to dive into the “latest and greatest” offerings earlier this year. I went in willing to spend what was needed to put myself in the best position possible replacing older amps I ran happily for many years.
Auditioned Purify and Hypex based models and also AGD. ( had also heard those earlier, as well as many other top contenders). Decided to go for broke and tru out the $3K Cambridge Evo 150 all in one device which uses Hypex. It was a keeper.
Honestly each amp I heard knocked it out of the park. The Evo brought my entire system up to date in one shot in a smaller package for less than I had owned prior. The quality of the technology these days puts a lot of old arguments and sweating about what is good or not to rest, at least for me . I am a music lover, a hifi enthusiast and deal with technology for a living . Looking forward to hearing the Atmasphere amps to see and hear what they do. My ears are always open and receptive.
I have been enjoying the Rogue Audio Pharaoh II for 2 weeks now, Tube pre section and Hypex N-Core power section. Agree with @mapmansome great sounding stuff out there.
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.
@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.
@holmzI 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.
@kuriboAt $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.
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.
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.
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!
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.
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 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.
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.
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?
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...
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...
@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
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