Atma-Sphere Class D… Amazing

@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.

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.

@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.

@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.

 

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

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

@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 thanks man sent u a message! 

@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.

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? 

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.

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

@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. 

@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!

Would these amps drive higher impedance loads easily? Let’s say Classic Audio Loudspeakers. I know only a handful of folks to include myself and Atmasphere who own T.1 series of the Classic Audio Loudspeakers. I own the T1.5s. These are often mated with the OTL Novacrons. I drive mine with McIntosh MC2301. Wondering if the new class Ds have been tested with higher impedance loads such as the Classic Audio Loudspeakers. Considering another set of amps to add to the setup, not replace anything. 

Are you still planning to build a version with somewhat higher power output?

We started with 100 W into 8 Ohms, 200 into 4 simply because if you really need more power than that your speaker is impractical. The exception seems to be ESLs like the Sound Lab, which are easy to drive in that they don't need an exceptional amount of power, but challenge solid state amps because the bass impedance is so high (30 Ohms).

We would like to make a more powerful amp, but to be noticeably more powerful than what we have already, it would have to be 600-800 Watts at least. This is simply because of the logarithmic character of the ear, which is why deciBels are used to measure sound pressure.

This kind of power won't be possible with the existing module. As always, the challenge will be to keep distortion down and keep it benign.

Yes, but I think it is more evident with tube amps than with s-state?

Yes.

Regardless of the amplifier though,  its distortion will always be higher driving a lower impedance. For this reason, if sound quality is your goal your amplifier investment dollar will be best served by a higher impedance speaker, all other things being equal (which of course they never are...).

However the class D seems to do nicely on lower impedances. Our local dealer likes how they drive the Magnaplanars in his store.

Yes, but I think it is more evident with tube amps than with s-state? The MA-1s can sound ok with 4 ohm (maybe), quite good with 8 ohm, but to know what they are really capable of, you need to go up - my speakers are 16 ohms, staying between 13 and 17 ohms above the bass impedance peaks, with efficiency:  92 dB/1 watt.

I love my MA-1 amps, and have learned to live with them, using NOS tubes, turn them off after listening, and so on. The best advice I got from Ralph was to match them with optimal speakers.

I would say that advice applies to any amplifier.

I hope Atma-sphere are successful with the new class D amps. This is certainly well-deserved. I love my MA-1 amps, and have learned to live with them, using NOS tubes, turn them off after listening, and so on. The best advice I got from Ralph was to match them with optimal speakers. Is this the case with the new class D amps too? Before the MA-1s, I had the huge Krell FPB600, and was told that it could drive "anything". That wasn't quite true, however.

@sdl4 

I would also be interested in higher power monoblocks, something in the range of 400 to 500 Watts into 4 Ohms. I want to be able to crack the foundation when the urge arises.

@atmasphere  Thanks for letting me know about the HiFi+ review. I was able to track it down, and it presents a very positive view of the sound quality of the A-S Class D amps. Going forward, these monoblocks will be high on my list of amps I'd like to audition in my home system. Are you still planning to build a version with somewhat higher power output?

Thanks for any further thoughts based on your extended experience with the A-S Class D amps. 

@sdl4 There is a review in this month's (June 2023) HiFi+ magazine. The reviewer had given us a very nice review of our M-60 triode OTLs about 2 years ago. He does make some comments of comparison. In both cases he was using the DeVore O96s.

@tubeguy45 

Can you comment on the fullness and tonal richness of the A-S Class D amps in your system? So many of the new generation of Class D amps (whether GanFET or MOSFET) receive praise for their resolution but are rarely described as outstanding in terms of warmth, smoothness, and richness of tone. I'm thinking of the naturalness and realism of voice and stringed instruments (especially guitars and upright bass) that emphasis tonal quality in the midrange and bass. My personal tastes value tonal balance over high-frequency pyrotechnics, but not everyone shares my tastes.

Thanks for any further thoughts based on your extended experience with the A-S Class D amps. 

I have had the Atmasphere Class D in my system with the MP-3 mk3.3 for over 1 year now and the transparency and resolution are simply amazing 

Happy Owner…HIGHLY RECOMMEND 

Loving my Gold Note PA-10 hybrid class A-D GaN but still listen to my tube amps also.  A class D GaN mosfet nobody seems to have on their radar. 

Brawn and brains: Gold Note’s PA-10 power amplifier | Darko.Audio

Getting back to saved discussions in my email, just got around to reading this.  On balance, informative and educational (thanks, Ralph).  For now, I will stay with my A-S M60's, but stay tuned about these amps.  

The other part of the question....can they be made differential from INPUT to OUTPUT, as many conventional SSs are (ML, Pass,Moon, etc)? Is there a point?

@fredag

Things are a bit different when you’re employing switching technology, but FWIW the comparitor (which is at the heart of any class D amp) we use is a balanced device. The reason to go fully differential (we’ve been doing that with our tube amps longer than anyone else as far as I can make out, since the mid 1980s) is to reduce distortion and noise. The distortion sources in a class D amplifier are very different from what you encounter in regular non-switching circuits. So the need isn’t the same.

@atmasphere Great! I use only balanced cables at home. The other part of the question....can they be made differential from INPUT to OUTPUT, as many conventional SSs are (ML, Pass,Moon, etc)? Is there a point?

@fredag They have a balanced differential input (and RCA inputs are provided too). I run them balanced at home.

@atmasphere Thanks! How about balanced operation. I understand the amp is not balanced/differential....can it be made with class D? (not ONLY balanced imput)

@fredag 100W with 8Ω, 200 with 4Ω. Current limit protection will kick in with lower impedance loads- as long as not to full power the amp will double its output power, but will reach its protection limit at about 250 Watts.

How does the output of a class D-amp (AS) varies with speaker impedance?

100W  with 8Ω....and then? 200 with 4Ω?

And what about really difficult speakers that can go down to about 2Ω?

Is there any limit to when the speaker load affects the performance?

@mglik , you may need more time to give a final judgement. Do you have now both, Atmasphere and AGD monos, which AGDs? 

The most transparent sound i have ever heard comes from my 5 watts SET tube amp. So i don't think that transparency is a distinguished feature of solid state amps. Do you perceive that AGDs are less harsh and more open? Thanks 

@lula 

Yes, I would say the main difference between the AGDs and the Atmas is that the AGDs do have more bloom tube-like sound. 

@mglik 

Thanks for your opinion.

I am auditioning Orchard Starkrimson D amp right now which sounds pretty good at reasonable price.

Unfortunately, I can not compare between Starkrimson and Atma D since there is no dealer of Atma D around Seattle area.

I may have to buy Atma D blind without prior audition although Ralph kindly offer return except shipping expense if not satisfied.

Thomas

mglik....would you say the AGDs have a more organic or bloom characteristic than Ralph's amps?