Atma-Sphere Class D… Amazing

@acresverde 

+1

@mihow     There is a BIG difference in saying that some Ganfets are made specifically for audio purposes as opposed to saying some Ganfets are more suitable for audio (read power amp) applications than others. Your post supports the latter...Alberto's post claims the former. What the actual truth of the matter is, I do not claim to know.

>Does the quote above suggest Alberto (AGD) is misleading in his saying his GANFETis made for audio?" 

Alberto is correct. There is a large variety of GanFET transistors that are made for different voltages and currents and switching times. Only some of them are good for power amps for a number of technical reasons.

GanFET transistors in audio amplifier work entirely differently than let's say bipolar or FET transistors in class A or A/B.

They are just switches, there is no transistor curve involved in shaping the sound like in Class A or B.

GanFET transistor used in class D are just a better faster switches then MOSFETs traditionally used in old Class D.  They produce a more square square wave resulting in bringing out all this magic otherwise lost in the grunge generated by MOSFETs. I wrote an illustrated primer paper on Gan FET explaining the mechanism in detail:

https://mytek.audio/shop/empire-ganfet-stereo-monoblock-introductory-special-free-b-amp-2#attr=11

Michal, Mytek Chief Designer

Beautiful!

Just finished reading through this thread that started in 2022. Glad to see it is still running as I have a pair of A-S Class D Monos arriving tomorrow. Unfortunately, my source is in repair - the balanced outputs were thumping. So full appreciation will wait a little while.

System is: Auralic VEGA G2 with LEO GX clock (VEGA is in the shop and using POLARIS in the interim) => Pioneer M-22 => Omega Super Alnico Monitors - HO with a pair of Rythmic 8" powered woofers and a pair of KEF KC62 subs.

The Pioneer is vintage 1970’s all Class A and is wonderful. Just very hot and 50lbs. Still looking for something lighter that will match its sound. From reading this thread and other opinions, I am very hopeful!

More to come.

Meanwhile....

Here’s a pic of my Pioneer heavyweight.

and the system as a whole

......Pete

That would be awesome. 

@atmashere

Ralph, I apologize; I did not mean to be rude or disrespectful. Sometimes, the Italian2English module installed in my cortex shows evidence of age and the need for an upgrade. Sorry for that, it was made in the last century. I just tried to share that the subject is more complex than it may seem. In any case, I am open to continuing the phone conversation and avoiding the potential misunderstanding of using a post like this. Thank you

@aw-agd, Likewise I would appreciate it if you didn't try to gaslight me.

Last popcorn post was unnecessary.

@atmasphere

Ralph, I am sorry to intervene again; your statement is wrong. I understand the decades of experience in Vaccum Tubes and amplifiers based on that technology; I know and respect your knowledge in that field,  but please do not make statements that are so generic and fundamentally incorrect on the specific.

There is not "a batch with low output capacitance" behind what we do; it is not a trick or lucky result; it is a real device explicitly designed to perform at best in a Class-D application, and no, of course not, it is not just the "output capacitance" that makes it ideal. I understand you are trying to pass a GaN System circuit as state of the art; business is business, I understand that too,  but please DO NOT COMMENT with an inaccurate and disarming simplistic statement about what we do, what we use, why we do it and how we use the component of the power stage of the AGD 100% designed amps. We will appreciate highly the courtesy. And again, if you wish to talk and understand more about how a GaN MOSFET, like every power semiconductor device, is an APPLICATION-SPECIFIC technology product, call.

Thanks

@dseltz

Sorry, Sir, but your statement is wrong. The semiconductor industry invests $'000 million yearly in application-specific optimization of MOSFET products (Si, GaN, or SiC). So, as a simple anecdotal example (and I am embarrassed to write this basic one), while your light switch belongs to the category of light switch, you can't use it to turn on a high-voltage circuit or a high-current device. It still amazes me to see how high the level of misinformation is and how profound the lack of knowledge on a specific technical and scientific subject is, yet still not enough as a barrier to prevent one from making baseless generic statements and trying to pass them as true.

@armstrod and @atmasphere

Thank you both for chiming-in! You just saved me from a big headache, inconvenience, and money. 

I have the remote now, but considering downgrading to the manual volume if there is a lot to gain in terms of sound quality.

@veerossi @armstrod If there's a difference its pretty slight. I've not noticed it.

@veerossi,

I bought my MP-3 used with the stepped attenuator and sent it back to Ralph to have the remote installed. While obviously I couldn't A-B them, I didn't notice any change in sonics. Ralph will tell you that the stepped attenuator is superior and I don't doubt it, but for me in my system I couldn't tell the difference and the convenience of having a remote in an already great preamp makes it worth it.

Special Ganfets? The Audion version one was good.....then he updated the circuit for a MKII......then again for a MKIII and now the best sound belongs to the new mono Duets (more money too).....apparently upgraded the input op amps as well.....all using the same GaNfet........So, what really makes a difference? Everything!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! GaNs seem to make the most sense but since every single thing you do matters....its the result that counts. Bruno has stayed with Mosfets (claims they are "fast enough"). He has just released a new "second generation Eigentakt" Purifi circuit module (model 900) that does over 300 watts into 8 ohms and over 900 watts into 2 ohms. Suppose to sound better than the last two models (400 and 700) he made. Specs are off the charts. How would a modded dual mono version of the VTV amp using these stack up against the latest more expensive GaN amps? We shall find out soon as I am getting one of the VTV dual mono amps in and will do my magic mods to it and do some comparisons......Should be fun. However, enjoy what you have right now.....this is the only moment that matters.....there will always be something better down the road......and hopefully cheaper. (Hey, some of us cannot afford a $6K amp......my whole stereo is $6K!)......Of course, I make some stuff by hand (speakers and cables and cable risers and tweaks)....and mod cheap stuff (DAC, transport and amp) to make super sound.

Has anybody had the experience with the Atma-Sphere MP3 preamp- going from manual volume control to remote volume control? I want to know what kind of difference in sound quality. I've already tube rolled it and it sounds great. Upgraded power cable definitely made a nice improvement as well. A SR purple fuse made a nice difference as well. Mine already has the v-cap package. Looking to squeeze all I can out of this preamp. I have the remote now, but considering downgrading to the manual volume if there is a lot to gain in terms of sound quality.

The Class D monos arrived yesterday and are hooked up and have played for nearly 9 hours. System information:

Auralic Aries G1.1 streamer > Bela Canto Dac2.8 AES/EBU input > A-S Class Ds. via XLR input. Interconnects are DH labs (DH-110 and Air Matrix Cryo). Speaker cables Kimber 12TC. Speakers are Totem Forest Signature.

Simply put, this is the best amplifier I have ever had in my system - the only two that come even close are the Pass XA30.8 and the Benchmark AHB2. There is a wholeness that makes it seem trite to analyze the sound spectrally in terms of highs, mids and lows. To use an imperfect analogy, some writers’ prose is so "perfect", that you get a sense that their writing is inevitable and that any change to it can only be for the worse. I am no literary critic, but I recognize it when I see it (Ian McEwan comes to mind, sometimes Paul Auster, always P.G. Wodehouse). To my ears, these amps have a sense of rightness, a wholeness that transcends anything I have ever heard.

Truly, a more fitting name for a brand could not be devised - I’m sure many of you know that the name is a play on the Sanskrit word for soul - Atman or Atma. If these don’t get to the soul of music, I don’t know what else does.

@atmasphere, I only regret that it took me decades to finally stumble into your work - well, I am here and here I intend to stay. This is inspired work on the part of you and your team.

A brief history of gallium nitride (GaN) semiconductors

Thanks for responding @atmasphere. In a interview, Alberto says he was involved in the initial development of GANfet. I believe he said he bought the stock and patent for the Mosfets he uses. 

Does the quote above suggest Alberto (AGD) is misleading in his saying his GANFET is made for audio?

No- not in my opinion. IMO it suggests he had a batch made that have low output capacitance. Low output capacitance reduces ringing in the output section (which is also caused by circuit board trace inductances and power supply issues- they can be in parallel with the output capacitance of the device which results in ringing and noise) as it switches and thus helps the devices to run cooler. The ringing can be controlled by a snubber filter but the output devices will still run hotter. So a low output capacitance is desirable.

In practice we found no need for a snubber circuit as there was no detectable ringing. IMO GaNFETs allow for lower noise designs. I think this is very important as switching noise and parasitics can mess with digital equipment even it the amp meets EU emissions directives. So you want to be many dB below the maximum allowed by most government entities. We found that many tube amplifiers radiate more noise than our class D.

@docroasty

Thank you, that's good to know. Weird, about the power meter led - it seems to be quite common, although I read somewhere that Carey did fix the issue back in 2018 or thereabouts.

@srama

yes, I did. I got the ultimate upgrade. fed from a wavedream net and dac stack. hooked up to the Atma-Sphere monos using TWL Spirit ii xlr. I really like this combination. I'm using it with headphones though (abyss TC Phi). the overall gain is a bit high but there are gain controls on the cary, and I reduce the output volume at the dac too.

lovely sound imo. great low end, lush mids, and sweet highs. I have no intention of changing out the cary pre. although somewhat annoyed at the black gloss finish as it does collect microscratches even when using a microfiber cloth to wipe it down. also, the blue light led on the power section failed, but my local dealer got it fixed really fast. 

@docroasty - curious to know if you ever did connect your SLP-05 to the Class d monos, and if so, whether you could share your impressions? Are they the standard or the ultimate upgrade version?

Thanks!

Right, like my bedroom light switches were designed for my bedroom light. Much different than my dining room light switch.

A transistor is simply a switch. It can also amplify a signal. It can be used in the design of an amplifier, but nothing can make it designed specifically for audio. It is simply the switching and amplification properties can be adjusted to fit the circuit that is being designed. All amp that use GANFET (Gallium Nitride field-effect transistors) use a GANFET designed for audio. The audio equipment it is in.

"Does the quote above suggest Alberto (AGD) is misleading in his saying his GANFET is made for audio?"

No.  His GANFET was designed with audio as the use case.

Does the quote above suggest Alberto (AGD) is misleading in his saying his GANFET is made for audio?

@atmasphere

I am happy you believe that "The only parameter that can make a GaNFET more suitable for audio is a low output capacitance. Other than that, there's no way to optimize a GANFET for audio."

Thank you!

I meant every word. It’s easy when it’s the truth :)

They should be arriving this Friday, so I will hook it up to the Auralic and Bel canto front end. I am now strongly leaning towards the Bryston BR-20, so that will be my eventual pairing with the A-S monos.

It’s been a while since I’ve posted listening impressions, but I will do my best! As I get older, I focus less on deconstructing the sound and focus more on tonality,  emotional content and realism.

@srama Those are very kind words directed at @atmasphere.  I hope you enjoy your new monos. Please let us know how they sound in your system.

@srama No.

One more question for @Atmasphere. I have Kimber 12tc speaker cables which have an unusually high capacitance - (Cp) : 494 pF / meter. I have read of people having issues using this cable with certain amps (Ayre, for instance). Any concerns with the Class D monos?

@atmasphere, thank you. My current Bel Canto is a balanced preamp/dac. I’m just hoping to lose one more box by way of the Auralic streamer, since I’m replacing a single stereo amp with two of your monos. Real estate being a premium and all that. I am considering a Bryston BR-20 but balking at the cost a little bit.

I also want to add that one of the main reasons I decided to try out your offering is because of your openness, clarity and obvious expertise on this and various other forums. I have never seen a manufacturer engage in quite so refreshing a manner with seemingly limitless patience and without a trace of defensiveness. I decided to buy a new pair from an authorized dealer as a mark of appreciation, even though there is a used pair for sale currently on another website.

I have been a member at AudioGon since 1999 or thereabouts and it has been years since I have engaged in these forums - you inspired me to break a long silence. I hope to share my impressions once I familiarize myself with the monos.

Ive got no skin in the game and I hope to compare both BUT there is definitely more Atmasphere's used ones showing up in the marketplace if you pay attention than AGD ones.  Whether or not thats because more ATMA's have been sold than AGD I dont know. 

The fact still remains that Albertos amps use a switching device nobody else can source. Again, one that was designed for Audio, not for a battery charger or DC power supply. 

The only parameter that can make a GaNFET more suitable for audio is a low output capacitance. Other than that there's no way to optimize a GANFET for audio.

GaNFETs are designed for high power switching applications. While that might include a SMPS or battery charger, in such applications the cost of the output switching devices can play a pretty big role in the device used. So a battery charger is far more likely to use a MOSFET instead owing to an order of magnitude lower cost. GaNFETs are more likely to be motion control or other high power application (such as class D operation) where precision high efficiency/low noise switching is important. 

Anecdote department only: we have more than just 3 customers that have compared the AGD to our amps and the result was the other way 'round (one of them commented above). In the end anyone will still have to try it out and see.

@srama I recommend a balanced preamp if you can. That's what we use here in the shop and what I use at home.

Waiting for a pair of A-S Class D’s to arrive and very excited. Any suggestions on preamps? Ideally an analog preamp with dac or an integrated solution combining analog, Roon Ready streamer and dac. Please don’t recommend the Eversolo A-8 :)

I currently have an Auralic Aries G1.1 streamer (no dac), Bel Canto DAC2.8 dac/pre and Ref501S. I look forward to evaluating whether the A-S are a significant step up and how much. Running Totem Forest Signature speakers.

@mikepowellaudio, are you not an AGD dealer?   Assuming so, maybe you should at least drop that disclaimer in your post before you enter a competitor's thread and dump on the product. 

I'm also not getting the point of your not so subtle jab 'If a "bargain" is what you are after, then maybe Ralphs are better for your pocketbook.' when his Monos sell for approx the same as the AGD Tempo STEREO Power Amp.

I do agree with your ".02c" part though :)

@cymivka I debated between Atma- Sphere and AGD monoblocks for my second amp purchase.  Talked to both designers.  I settled on the Atma-Sphere so I have never heard the AGDs.  I do have a LSA Voyager Gan modded amp that sounds really nice.  The Atma-Sphere bests it in soundstage, low end and pristine clarity.  Nevertheless, the LSA remains a damn fine amp and, for the money, hard to beat.

LOL, Superior ?... Its not true in my opinion. Ive now had 3 seperate customers compare them and all of them liked AGD better. 

If a "bargain" is what you are after, then maybe Ralphs are better for your pocketbook. The fact still remains that Albertos amps use a switching device nobody else can source. Again, one that was designed for Audio, not for a battery charger or DC power supply. 

Then we've got the aesthetic, which of course, is a work of art in my opinion, and after spending thousands, I'd like something that looks like it.

Finally nearly ANY solid state amp is going to have tighter bass than a tube. so either of these solutions will control your woofer better. The beauty of the AGD for me, at least was its speed and lack of grain. Extremely articulate without being harsh. 

just my .02c

IME, the Atma Ds are far superior to the AGD Audions (MK II).

And a bargain. What is also super impressive and one of a kind is that Ralph actually recommends his Ds over his much more expensive and highly thought of tube amps. And tubes are a hassle and a problem in the Summer. His Ds have much better bass, sound at least as good as his big tube amps and are bullet proof.

Hey there Jaymark.  as suggested earlier you have a lot of experience with ganfet class d's. (and other great amps)  I think many here on the gon would love to hear your comparison of the atmasphere class D amps that you already like to the AGD Audion mkiii's that are a lil pricier than the atmaspheres.   Or, perhaps you already have made the comparison and I missed it.   I read on some opinion site somewhere that the Audions out performed the Atmaspheres, but that was the only comparison I've come across, so far.    I find detailed amp comparisons in general very interesting.  Hope you keepem coming.

Thanks.

Michael.  

@kykat I am using a top end Aric Audio Motherlode preamp and Aerial Acoustic 7T speakers that were essentially gutted and rebuilt  by Doug Jesse at ASi Teknology.  I also use a Space _Tech Super Rectifier via an umbilical cord to my preamp.

Congratulations @jaymark !

What preamp and speakers are you using now?
 

MYTEK is an awful company and their customer service is horrid. I learned this first hand years ago, purchased a Brooklyn Bridge, service issue after service issue. Finally just binned it and took the loss,  no way I could sell it in good conscious. Some my love their products and company bit I would steer clear. 

@tweak1  After seeing the ASR results of the Mytek Brooklyn Bridge II, I wouldn't have much hope that Mytek can produce a good GaN amp. Heck, they failed at their main product - a DAC!

I listened to a Part-Time Audiophile podcast this morning featuring the brains behind MYTEK, discussing digital amps, specifically GaN tech and that they have introduced their own monoblocks.  I think you'll all enjoy it

Glad to hear you went for them @jaymark. It’s been just over 8 months since I’ve had mine and still loving them. Not missing my old tube integrated at all. I’d highly recommend the Atma-Sphere MP3.3 preamp as well.

I heard them at a show with the Big Classic Audio speakers that Atmasphere typically partners with at shows. I couldn’t find a fault. Then they switched to the Atmas tube amp and frankly I struggled to hear a difference. So there you go FWIW. Overall teh Atmasphere/Classic Audio room sound was teh best I had heard to-date compared to prior years where it was tube amps only. For a year or two prior, the sound came off too me as a little bright and somewhat fatiguing for whatever reason.  THis was with tube amps only.  Probably they adjusted better to acoustics the big conference room they were in each time.  The room is usually manned by folks from Classic Audio, I believe.

Cool. Or, even better +200 hours.

@pstores i just unboxed and hooked up my Atma-Sphere monoblocks this morning.  Cold and straight out of the box i was very impressed.  They sound very clean, pristine, neutral and very natural sounding.  I am letting the play all day streaming Qobuz.  Cant wait to hear them 10 hours later.