Atma-Sphere Class D Mono blocks

Gregadd said:

Just to show you I was paying attention professor.

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Thanks. IMO a discussion about distortion and how that is what is the 'sonic signature' of any amplifier is pretty important as well. Also how feedback can cause problems and how it can be a benefit (its gotten a bad rap IMO because its usually applied inappropriately). Also how the human ear perceives distortion, and the mechanisms about how the ear perceives sound that get ignored.

"...Also how the human ear perceives distortion, and the mechanisms about how the ear perceives sound that get ignored."

The ear is a purely mechanical device. Perception is the province of the brain. So to speak.

Gregadd said:

"...Also how the human ear perceives distortion, and the mechanisms about how the ear perceives sound that get ignored."

The ear is a purely mechanical device. Perception is the province of the brain. So to speak.

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Yes- When I use the phrase 'the ear' I usually mean the ear/brain system.

Hear Here said:

I think the simple answer is just to arrange a home trial of a couple of top-drawer Class D amps. Sadly, I've not yet had the opportunity to hear the Atmosphere monos, but I do use an amp featuring the Purifi Eigentakt technology. This is considered by most as the best out there and certainly I've not heard better.

There are plenty of cheap Purifi amps listed on Ebay, etc that are often garage-built using the Evaluation Board, but I'd suggest that the much better option is to go for a big-brand offering where they build under license after maximising performance in conjunction with Purifi. The amps that are probably top of the pile are NAD's M23 power amp or its sister M33 all-in-one, or the T & A A200 power amp or the M200 mono amps. I'm hoping the Atmosphere may out-perform these amps, but I'll wait for their integrated before jumping ship from the NAD M33.

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Regarding the Purifi module, Bruno Putzeys has said that the design of the input buffer is very important to the overall sound. For an implementation such as VTV Amplifier, the choice of buffer can nearly double the price of the amp.

@Atmasphere is the input buffer as influential to the sound of your amplifier?

From my own experience, Class D amps take a long, long time to fully break in, therefore it is beneficial to know accumulated hours of play for a home demo unit.

When doing auditions comparing any class-D amplifier to a tube amplifier, keep in mind that class-D amplifiers have a very low output impedance. In this case around 0.01 Ohms.

Your tube amp has a much higher output impedance which will put out more power at the frequency where your woofer has an impedance spike. For most large woofers this is in the 50Hz range, plus or minus. When using a tube amp you will have a few DB more SPL coming out of your speakers at this frequency. With the ultra-low output impedance of a class-D amp this interaction does not happen. So it may appear to sound thinner.

This can easily be compensated for if you are using subwoofers by re-adjusting them to make up for the difference. Which is what I did on my system when switching from the M60’s with their four-ohm output impedance to these class-D’s with 0.01 Ohm output impedance.

The bass becomes much more controlled, accurate and detailed overall with the class-D’s iron grip on the woofer.

If you are not using subs you can try moving your speakers closer to the wall to make up for the difference. Either way this will need to be compensated for before making a final decision if moving from tubes to class-D is right for you and your system.

Point being it’s not just plug and play without making any other adjustments when changing between these two topologies.

As someone who enjoys Class D and sees its place in the future of audio (among other topologies), I have noticed many new designs that are the opposite of small/efficient/Class D topology. Two examples:

Amps like the the Gryphon Apex monos, that weigh a combined 900 pounds (and are 35" deep)! Saddle up!

Or something like the new McIntosh MC451 that has two outputs, one powered by the solid state section and one by the tube section. The amp has an adjustable crossover to tune the different sections that feed highs/mids (via tubes) and bass (via ss).

PYP said:

Regarding the Purifi module, Bruno Putzeys has said that the design of the input buffer is very important to the overall sound. For an implementation such as VTV Amplifier, the choice of buffer can nearly double the price of the amp.

@Atmasphere is the input buffer as influential to the sound of your amplifier?

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Yes. The input buffer can make or break the amp. It need not be expensive though, since its a fairly simple circuit.

Hello Ralph,
Thanks for sharing input on the new Class D amplifiers you have released. I am very tempted to try them but so far all the discussion about how they sound has been about low overall distortion, a neutral tonal balance and controlled distortion created to mask harshness and make the overall sound as smooth as possible. Since I value refinement above most other sound qualities it sounds like the Class D amps could work well for me.
The other qualities I value are speed/ micro dynamics and separation of instruments which I have not seen being discussed about the Class D amps. My current amp has exceptional speed, micro dynamics and separation. Quite amazing actually as it sounds like distinct musical instruments and vocals are piped in on their own channel they are so easily heard. I just wish it had more power and was more neutral. Currently using 90db speakers.
Can you or a user of the Class D comment about speed, micro dynamics and separation? Thanks.

avanti1960 said:

Can you or a user of the Class D comment about speed, micro dynamics and separation? Thanks.

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I know users can. My own impression stems from working with our OTLs which are known for speed and separating the instruments as you suggest. IMO the class D does it just as well if not better; I've been playing them at home and don't miss the OTLs at all.

Atmasphere said:

I know users can. My own impression stems from working with our OTLs which are known for speed and separating the instruments as you suggest. IMO the class D does it just as well if not better; I've been playing them at home and don't miss the OTLs at all.

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I guess your ears have finally given up…

morricab said:

I guess your ears have finally given up…

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Pretty harsh... Have you heard Ralph's new amp?

We all would like to hear it. I have heard the Merril Audio.

avanti1960 said:

Hello Ralph,
Thanks for sharing input on the new Class D amplifiers you have released. I am very tempted to try them but so far all the discussion about how they sound has been about low overall distortion, a neutral tonal balance and controlled distortion created to mask harshness and make the overall sound as smooth as possible. Since I value refinement above most other sound qualities it sounds like the Class D amps could work well for me.
The other qualities I value are speed/ micro dynamics and separation of instruments which I have not seen being discussed about the Class D amps. My current amp has exceptional speed, micro dynamics and separation. Quite amazing actually as it sounds like distinct musical instruments and vocals are piped in on their own channel they are so easily heard. I just wish it had more power and was more neutral. Currently using 90db speakers.
Can you or a user of the Class D comment about speed, micro dynamics and separation? Thanks.

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I can comment on a few things you mentioned. I don't think the amps mask harshness with a certain tonal balance. If fact after the amps had broken in fully they revealed some distortions and what I would call digital hash in my front end that I didn't hear before. Also the overall balance was a bit too neutral for me in that I felt like some musicality my previous amp had that was synergistic with my system was missing. I believe this musicality was actually a slight lack of transparency - a veil if you will that was pleasant in nature. This has caused me to move in a couple of directions. I changed finally from digital volume control (Leedh in the Lumin, and DSP in my Roon Core) to a very resolving preamp that has just a bit of sweetness on the top. This increased soundstage, detail, scale, dynamics and bass while having just a soupcon forgiveness on the top octave (Denafrips Athena) which I typically like. I also looked at every step of my digital chain and improved cabling, EMI rejection, power filtration. I also have been improving my internet/network delivery with better fiber firewall, SMPS replacements etc. I also upgraded my Lumin U2 Mini with a Linear Power Supply. This on ongoing, and wouldn't have been possible without the increased awareness the amps provided me.

Also, one of the things the amps did for a lot of the classic Soul R&B that love is I could hear more backup singers in a track, and hear specifically where they were placed, new subtle instruments appeared in mixes I hadn't heard before. In one case, one piece I've been listening to for over 30 years, there was a thumping I could hear that I though was part of the drum kit was actually the singers foot on the stage floor keeping time for the group. On golden age classical recordings, I could hear more clearly how the orchestra was arranged, deeper soundstage with more precise placement, additional instruments showing up, more strings and being able to 'see' their configuration. Things like that were constantly revealing themselves to me on music I was intimately familiar with on the new amps. All of these things happened because of things like speed, microdynamics and timing, are superior. But I don't think in those terms much when evaluating audio.

I had some of the questions and likes Avanti1960 had. In addition, I like solid state amps as they seem to provide better transient response and leading edges over most tube amps. Will the Atmosphere Class D do that, or do they have more of a rounded, and polite presentation? I like my amp to do Metallica as well as Ella, I like a solid crescendo, etc. I like texture and timbre of instruments but not negative colorations. I also like an extended high end without being strident or harsh.

morricab said:

I guess your ears have finally given up…

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That is one possibility- but if so, so have all those that have bought the amps. There are a number of them that have compared the amps to our OTLs and also to SETs, whereas you have yet to hear a set and seem to be basing your comment on experience with some other amp or amps that isn't made by us. Based on that, Occam's Razor suggests my ears are working well enough.

Atmasphere said:

That is one possibility- but if so, so have all those that have bought the amps. There are a number of them that have compared the amps to our OTLs and also to SETs, whereas you have yet to hear a set and seem to be basing your comment on experience with some other amp or amps that isn't made by us. Based on that, Occam's Razor suggests my ears are working well enough.

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Given how many poor sounding class D amps have sold well your numbers of class D amps sold is not indicative of much of anything

morricab said:

Given how many poor sounding class D amps have sold well your numbers of class D amps sold is not indicative of much of anything

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That might be true- save for one thing.

We've been in business nearly 50 years. People that are buying our amps are buying them for the same reason that we reasoned we could sell them: we've tried really hard to do the right thing over the last 50 years or so; to make an amp that does not measure up to our standards isn't in the playbook. Our customers know that. People that wanted our amps for years but couldn't use them with their speakers know that. People that know about us through our reviews and reputation suspect it. Somehow for the most part I've managed to not shoot that reputation down by my participation on these forums

Things would end abruptly if I/we were misleading anyone. People figure things like that out pretty quick.

I figured I was going to get resistance. The idea that a solid state amp could challenge tubes of any sort is anathema to any tube lover.

Any one of those people will tell you that you have to let your ears be your guide.

Right now, if I might be so bold, you aren't doing that. You're allowing your understandable prejudice about class D (likely brought on by prior experience) guide you. You are also not looking at what people are saying, even on this thread. Instead there is the good ol' rubber stamp; if its not SET it must suck or something like that. I get it.

When you really get that distortion is what we hear that is different between amplifiers (and also, FR since many amps with high output impedance will not have a flat FR), then you can see how a class D might be really able to sound right- to be smooth, revealing and engaging.

Reading your argument Ralph, makes feel like the Princess in the Princess and the Pea. I wake up bruised and uncomfortable, but there is nothing wrong with the mattress I am sleeping on.

Gregadd said:

Reading your argument Ralph, makes feel like the Princess in the Princess and the Pea. I wake up bruised and uncomfortable, but there is nothing wrong with the mattress I am sleeping on.

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Those opinions were “SET in stone.”

morricab said:

Given how many poor sounding class D amps have sold well your numbers of class D amps sold is not indicative of much of anything

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Ralph

I think our friend morricab is still using shellac cylinders for his music. He deserves a strict ignoring – at least until he’s tried a modern Class D amp and can comment from a knowledgeable point of view. I’m sure he’s remembering the Tripath Class D technology that really wasn’t that great. Things Class D have moved on swiftly since then.