Atma-Sphere Class D Mono blocks

[Nuforce]

do you think that could be a factor in your in-home evaluation?

No. I have a reasonably objective ear, and I will know if I prefer one over the other relatively easily.

 

[ecolnago]

No. I have a reasonably objective ear, and I will know if I prefer one over the other relatively easily.

You might actually find yourself a bit surprised. Have had the A-S class d's going on a year now. Intent was (is) to see if there's something out there that could both suite my tastes and alleviate my never-ending (OCD-ish) urge to replenish my M-60's tubes.

To my ears, in my system, the class d's and the OTL's are just slightly different animals. Both sounding wonderful, but each with different attributes. The body, control and authority the d's offer in the lower frequencies is quite impressive. The M-60's can't match it. However (with suitable recordings), the M-60's offer a 'disappearing speaker' presence that the d's (nor virtually any other amp I've had pleasure to hear) can't touch.

Again, just my purely subjective take. Wishing I had a tolerant friend (wife's friendly, just not that into it) to assist in a blind a-b test setup just to eliminate any/all biases I have, as I, too, think I'd always be able to audibly discern the OTL 'magic'.

System: A-S MLS-1 upgraded to MP-3 by Ralph, Lumin T2 serving Qobuz, Joseph Audio Pulsar 2 Graphene(s) w/ a couple DIY class-d powered subs in a 14'x 20'x8.5' room.

 

[Nuforce]

You might actually find yourself a bit surprised. Have had the A-S class d's going on a year now. Intent was (is) to see if there's something out there that could both suite my tastes and alleviate my never-ending (OCD-ish) urge to replenish my M-60's tubes.

To my ears, in my system, the class d's and the OTL's are just slightly different animals. Both sounding wonderful, but each with different attributes. The body, control and authority the d's offer in the lower frequencies is quite impressive. The M-60's can't match it. However (with suitable recordings), the M-60's offer a 'disappearing speaker' presence that the d's (nor virtually any other amp I've had pleasure to hear) can't touch.

Again, just my purely subjective take. Wishing I had a tolerant friend (wife's friendly, just not that into it) to assist in a blind a-b test setup just to eliminate any/all biases I have, as I, too, think I'd always be able to audibly discern the OTL 'magic'.

System: A-S MLS-1 upgraded to MP-3 by Ralph, Lumin T2 serving Qobuz, Joseph Audio Pulsar 2 Graphene(s) w/ a couple DIY class-d powered subs in a 14'x 20'x8.5' room.

I have no interest it their bass performance. My active system crosses over at 120hz.

I would only keep them if they could outperform in mid range and upper frequencies.

I've not heard the lower range MA-60 but I assume they aren't as good as the MA-1. Mine also have the Vcap upgrade.

 

[D.Duttilleux]

I have found a dealer here in the UK who has a pair for home audition so I'll arrange that closer to the summer. I still remain convinced they won't sound as nice as my MA-1s.

My magnepan ribbon tweeters will tell me the truth as these are what these amps drive and they are extremely revealing.

Maybe not, with your Magnepans, but those MA-1s are huge, heavy and heat-generating beasts and replacing tubes will probably cost as least a much as 1 Class D mono, or perhaps even a pair.

 

[DetroitVinylRob]

Maybe not, with your Magnepans, but those MA-1s are huge, heavy and heat-generating beasts and replacing tubes will probably cost as least a much as 1 Class D mono, or perhaps even a pair.

A little north of 1,840 USD today to completely retube a pair of MA-1s perhaps. This is considering the retail price of about $30 a power tube and approximately $100 for each of the signal tubes (NOS). Now I’ve got backstock that I picked up eons ago so not that expensive here! Not sure what Ralph’s pricing might be.

 

[Nuforce]

If I was worried about electricity and tube costs I wouldn't have bought them! Honestly, I don't understand the issue. The MA-1 is one of the great amplifiers and the pride of ownership is very high.

I'll book a home demo of the class D and I'll keep an entirely open mind. I do find the need for AC in the summer months a bit annoying, I will admit, due to their heat output.

 

[D.Duttilleux]

Take no offense. I have fond memories of driving cars with big V8 engines, up to 8.2 liters.

As for audio, there's a lot of convenience with Class D. While not nearly as advanced as the Atma-Sphere monos, I still enjoy my early Hypex-derived Class D amplifier (with linear power supply), which has been in operation virtually 24/7 for 17 years.

 

[DetroitVinylRob]

Yes, MA-1 Silver Editions, fully updated. Absolutely ??these amps!

I’ve been away on the gulf coast for a while, just looking forward to getting back into the kit and some quality listening. Had a few brief and enjoyable sessions with friends and some back and forward with the MA-1s. Some find it an either or, I’m not there (yet).

My first impressions is simply how much they sound like the OTLs. Very easy to listen to, very articulate, and offer a well balanced musical experience. They are different though in the way they present. Perhaps the mid bass is a little fuller, the D class is dead quiet when no music is playing, and they are on point right after you flip the switch, I don’t believe there is much change in sound at all as time goes by. I would say “as they warm up”, but they simply don’t, and for me, the chassis never feel above room temperature. Amazingly, no change in sound quality.

Ralph and his team have really accomplished something quite remarkable here.

More listening…

I will add a bit to my first impressions.

This whole hobby/pursuit comes down to personal tastes and to any outsider, what might seem to be infinitesimal neuance. Yet for us, it is the essence of what collectively allows a state of suspended disbelief. Where we simply let go (of everything) and focus on the joy of musical performance as opposed to the evaluation of the audio equipment performance.

Living with the MA-1 Mk.3.3 Silver Editions and the amazing D-class amps has really changed my mind about the possibilities of D-class. Its ultimate performance is truly regardless of architecture or elements and formulated in the hands (and ears) of the creator.

And yes, as a sidenote: there is considerable difference in performance though absolutely the same sonic character comparing the M60s to the MA-1 in my system. The wattage seems to prove out authoritatively throughout. Even at 98Db 16?. Not unlike the difference that can be brought by an active preamp as apposed to a passive preamp in my experience.

As I said earlier, imho these two are wonderful cousins, though present slightly different.

What I’ll add to my previous comment with this additional listening between the two is that the MA-1s have a bit lighter feel throughout with an added presence of what I would describe as “the room and space that the recording was captured in”. A sense of high frequency detail and space, or “AtmaSphere”. The new D-class focus on a very slightly fuller body with perhaps a bit more mid-bass and lower definition that is very musically satisfying, like comfort food during these winter months. Yet these are subtle differences as the two are so much alike. (All in my kit/in my room/with my tube roll). Ok, so here is how crazy it gets… could I biamp run the tubes on top and through the mids and run the D-class on the bottom?? Well, there goes any economy advantage. Once again, I just made it more complicated.

Of course to say that my observations are definitive for all or that these amps will not present differently in different settings would be utterly absurd. But take a long listen for yourself. For me, I simply cannot let go of my MA-1s at this time. Regardless of their (becoming rare) tubes and massive power consumption.

Time to put solar panels on the hill.

Ultimately, two incredibly well conceived and constructed power amplifiers!! Great job (again) Ralph

 

[Nuforce]

So bottom line, sounds like you prefer the MA-1 amps top and midrange, as I would have expected.

Re the tubes, I run the Chinese ones which seems to last pretty well. I average maybe one failure a year, so just swap out as I need to and recheck bias. And stock is plentiful.

 

[D.Duttilleux]

Nicely written Rob. It led me to read the 6 Moons review of the MA-1 MkII.3 Silver Edition.

"Compared to my BAT VK-75, the Atma-Spheres just offered more of everything: More detail, more extension, more transparency, better soundstaging, greater micro and macro dynamics, more extended and luscious high frequencies. The only area wherein the BAT bested the Atma-Spheres was in overall warmth. The Atma-Spheres, though able to go very deep with rock-solid imaging, did not produce the level of bass warmth that the transformer+ BATs do. Could I live with one and forget the other? I don't know. This is not a small quibble. I prefer warmth. That is why I love tube gear in the first place. Alas, for $4K more, the Atma-Spheres produce an assortment of sonic virtues (in light if oblong and hard-to-place enclosures) that is nearly irresistible if -- and that is a big if -- you have the cash. But as most of us know, this audio game is a matter of priorities. Put another way, bills get deferred, old cars driven, holes are attached to socks and endless trading goes up and over."

I prefer warmth as well, because warmth is inherent to natural sound.

After delving a little deeper into Class D technology, it seems that a distortion signature dominated by the 2nd order harmonic with a lower (level) 3rd and no higher order harmonics (see image) is quite rare.

 

[morricab]

Nicely written Rob. It led me to read the 6 Moons review of the MA-1 MkII.3 Silver Edition.

"Compared to my BAT VK-75, the Atma-Spheres just offered more of everything: More detail, more extension, more transparency, better soundstaging, greater micro and macro dynamics, more extended and luscious high frequencies. The only area wherein the BAT bested the Atma-Spheres was in overall warmth. The Atma-Spheres, though able to go very deep with rock-solid imaging, did not produce the level of bass warmth that the transformer+ BATs do. Could I live with one and forget the other? I don't know. This is not a small quibble. I prefer warmth. That is why I love tube gear in the first place. Alas, for $4K more, the Atma-Spheres produce an assortment of sonic virtues (in light if oblong and hard-to-place enclosures) that is nearly irresistible if -- and that is a big if -- you have the cash. But as most of us know, this audio game is a matter of priorities. Put another way, bills get deferred, old cars driven, holes are attached to socks and endless trading goes up and over."

I prefer warmth as well, because warmth is inherent to natural sound.

After delving a little deeper into Class D technology, it seems that a distortion signature dominated by the 2nd order harmonic with a lower (level) 3rd and no higher order harmonics (see image) is quite rare.

View attachment 125454

What amp is that a measurement of?

 

[D.Duttilleux]

This one.

 

[ecolnago]

Nuforce: At twice the price, I would certainly hope the MA-1's have something more going them that the M-60's don't beyond just more power, but that I don't know? Not having heard the MA-1's, I can't speak to the differences.

Didn't dawn on me, but my Pulsars are bi-amp-able. Just for kicks and giggles (and since the opportunity still exists) I'll try to find some time in the near very near future to wire things up and see what happens. Generally of a 'keep it simple' mindset and doubt I'd ever convince nor justify to myself devoting all the M-60's have to give to just my tweeters, but who knows?

 

[morricab]

This one.

Interesting, but I would like to see what’s happening below -80dB, which is as low as this graph goes. Nevertheless it looks quite clean on the harmonics (absence of power supply induced IMD).

 

[DetroitVinylRob]

So bottom line, sounds like you prefer the MA-1 amps top and midrange, as I would have expected.

Re the tubes, I run the Chinese ones which seems to last pretty well. I average maybe one failure a year, so just swap out as I need to and recheck bias. And stock is plentiful.

I’ll say this, it is only viable by and large to offer a product with currently available perishables. Call VTS Andy (or equivalent, if there is such a thing) he will set you up putting some Sylvania tubes in those MA-1s and you will be floored by the difference. I promise. Thank me later. As good as these amps are, the Chinese 6SN7GTB are (sorry) but, audio junk. No comparison. They electrically function, but that’s not saying much. My last set last just over 10 years, so is it worth the sound investment? Please, do yourself this favor. It will be like Christmas!

 

[D.Duttilleux]

Interesting, but I would like to see what’s happening below -80dB, which is as low as this graph goes. Nevertheless it looks quite clean on the harmonics (absence of power supply induced IMD).

You beat me to it > what's happening below -80 dB.

I made a list (that I can't find) with amps with such a signature > 2nd, lower 3rd and no higher orders above the noise floor.


During my research the concept of a PCM-based Power DAC (digital amplifier) came up, but it seems very difficult to realize. Ultimately, I ended up studying (industrial) LED dimmers and similar power converters.

 

[ecolnago]

Dead-on with you on the Chinese 6SN7GTB's. Gave them maybe 50 hrs. Put my old NOS Sylvania's back in. Night and day.

 

[morricab]

You beat me to it > what's happening below -80 dB.

I made a list (that I can't find) with amps with such a signature > 2nd, lower 3rd and no higher orders above the noise floor.


During my research the concept of a PCM-based Power DAC (digital amplifier) came up, but that seems very difficult to realize. Ultimately, I ended up with (industrial) LED dimmers and similar power converters.

Well, we don’t really see the noise floor in this FFT because of the scale. For sur the 4th is < -80dB as are others but how much below? FWIW, the Aries Cerat Concero 65s have -70dB H2 at 1W with all other harmonics falling away as desired.

It’s a nice little amp though…you have one?

 

[D.Duttilleux]

No, but it seems like an interesting amp to tame compression drivers.

 

[DetroitVinylRob]

Dead-on with you on the Chinese 6SN7GTB's. Gave them maybe 50 hrs. Put my old NOS Sylvania's back in. Night and day.

Night and Day, and most of, if not all of the spectrum in between