Atma-Sphere Class D… Amazing

@audioquest4life Into 16 Ohms they will make half of their 8 Ohm rated power. As you already know though, that's plenty for the T1s. You might have to adjust the rear panel controls slightly since the class D has a lower output impedance compared to a tube amp. I've been driving my T3s (also 16 Ohms) for the last 2 years and they work great together!

@atmasphere ,

Thank you for the response. That is great to hear that your new amps adequately power the T3s and the T1s. I think these amps would be a good alternative to the either the Novacrons or MA60s I was looking at. The thought of a compact killer amp sounds good to me, no pun intended. I will definitely try to see if I can find somewhere to demo these and see about a home audition. 

Is there an official answer whether or not it’s ok to leave the atma-sphere class d amps on 24/7?

Is there an official answer whether or not it’s ok to leave the atma-sphere class d amps on 24/7?

Its fine. The only concern is when turning a preamp on or off you might get a substantial thump so I would shut the amps off during those times.

I just got my atma-sphere monoblocks yesterday. took a few weeks upon ordering. they're bigger than I expected; can't fit them side by side on my rack. guess I will have to place them on the floor.

No instruction manual but I guess probably not needed. they came with a set of u-shaped pins to insert into the xlr ports; I've not used this before. do they have to be inserted when using RCA into the blocks? 

@docroasty 

I think I have a manual and can copy and send to you. I am pretty sure you only need the pin if you are connecting to a preamp (other source) that has only RCA outputs.

I honestly staggered the amps about the width of the overhang of the front plate and was able to put on my rack. If you are able to put them on the floor, though, you can get very short speaker cables for better sound.

I suspect Ralph may chime in and correct any mistakes I stated lol.

@dseltz thanks man sent u a message! 

@docroasty Use the shorting plug if you are using the RCA inputs on the amp. You insert the plug into pins 1 and 3 of the XLR input.

@dseltz about the only thing that jumps out is there is no manual for the A-S Class D amps :-)

I do have a question that, hopefully, @atmasphere Ralph might be able to answer:

I was watching a YouTube video from REL about connecting their subs to class D monoblocks. They recommend connecting their red wire to the amp’s positive speaker post and the black wire to chassis...not the negative speaker post. I’d prefer to hear from you if this is how it should be connected or if you recommend something different?

@docroasty In case you’re looking for ideas- here’s a pic of the setup I made for mine (that are on the ground) The braces are 3D printed and the wood it’s stained solid 1 1/2" thick walnut (to match my Tannoy’s). The aluminum feet have rubber rings in the bottoms. I’m happy with the way it all came out. Here’s a link with a pic. You can zoom in with your mouse wheel.

https://drive.google.com/file/d/1jESO2l6Tp43OVJFafkoTTUAr-GJQsbvQ/view?usp=sharing

@clio09 thanks for that info! i left the shorting plugs in the box and stored it away, as i dont use RCA often. looks like i'll have to get them out and keep them in the drawer just in case.

@veerossi dude, to say that rack is amazing would be an understatement. that looks fantastic!! by any chance, do you make those to sell? lol

it has been only two days since i've had the monoblocks. this is my first time using monoblocks. my other amps are Apollon Audio stereo 1et7040sa and NAD M23, both Purifi. i've had Kinki M7, another Apollon purifi (1et400sa) and Benchmark AHB2 previously. these monoblocks are extremely impressive..

there is a whole lot of detail in the music, but somehow there is also zero sibilance/edginess/etchiness. felt like there wasnt enough bass initially but seemingly on only day 2, the low end has filled in substantially. these monoblocks definitely sound different from my Purifi gear; a bit warmer, slightly fuller on the midbass region, slightly rounded up top. it is a very pleasant sound.

since i couldnt place them nicely on the rack, i have them stacked on a butcher block next to it. hooked up some simple xlr cables directly to the Meitner MA3 dac and using the dac for volume control. sounds fab and seems like such a simple setup especially for running in the amps during the day (dont want to use up tube life when not listening). I will try hook up the monoblocks to my Cary SLP-05 preamp this weekend and report back.

 

@docroasty Thanks. I'm glad you like it. I can make another one to sell to you, but we will need to discuss the details. Please DM me if you are interested.

I was watching a YouTube video from REL about connecting their subs to class D monoblocks. They recommend connecting their red wire to the amp’s positive speaker post and the black wire to chassis...not the negative speaker post. I’d prefer to hear from you if this is how it should be connected or if you recommend something different?

@veerossi I would hook it up to the red and black. If you run into trouble with buzz or hum, you can try tying to chassis, but I don't think its necessary.

Also in the hum and buzz department: some preamps and sources are not grounded. If using one of them and also the single-ended input of the amp and you have a buzz or hum, place a jumper between pins 1 and 3 of the XLR. You will only need this if the preamp or source is not Grounded.

@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.

Cool. Or, even better +200 hours.

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.

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 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

@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!

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. 

Congratulations @jaymark !

What preamp and speakers are you using now?
 

@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.

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.  

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.

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

@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.

@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 :)

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.

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.

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. 

@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.

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?

@srama No.

@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.

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.

@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!

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

"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.

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.

@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!

@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

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.

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.

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. 

A brief history of gallium nitride (GaN) semiconductors

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.

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.

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.

@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.

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.