Atma-Sphere Class D Mono blocks

[Atmasphere]

Is it as good or better than tubes?

We think so, which is why I have been saying that tube power amps are on borrowed time. The only thing I hear that tubes can do better is their overload characteristic; class D amps clip like any solid state amp does, which means you have to have enough power to do the job. Tube amps can have a very graceful overload.

Class D is even finally invading the guitar amplifier market (and not those cheap 'modelling' amps that started to show up about 15 years ago). Audiophiles don't like this fact, but the guitar market has been keeping tubes alive far more so than the audiophile market! As class D invades the guitar market its going to put a huge dent in the bottom line of tube producers. Things are going to look very different in 10 years!

 

[Ron Resnick]

The only thing I hear that tubes can do better is their overload characteristic;

You hear from Class D the same “liquidity” that tube lovers hear from tubes?

 

[microstrip]

Ralph,
Two technical questions: what kind of input topology do you use in the balanced mode and what is the switching frequency of your class D amplifiers? BTW, you should get a short code for them!

 

[Gregadd]

We think so, which is why I have been saying that tube power amps are on borrowed time. The only thing I hear that tubes can do better is their overload characteristic; class D amps clip like any solid state amp does, which means you have to have enough power to do the job. Tube amps can have a very graceful overload.

Class D is even finally invading the guitar amplifier market (and not those cheap 'modelling' amps that started to show up about 15 years ago). Audiophiles don't like this fact, but the guitar market has been keeping tubes alive far more so than the audiophile market! As class D invades the guitar market its going to put a huge dent in the bottom line of tube producers. Things are going to look very different in 10 years!

Ahem. if you will allow me to momentarily depart from my claim of gentility.
Are you not a major player in the tube amplification market?

No, as an anaudiophile I don't like it. My disapproval is not prejudicial but is based in fact. I agree, things are going to be different in ten years. Tube amplification has been on the endangered species list for my entire audiophile career. You can get a tube amplifier kit form Walmart for $299. As the saying goes", the reports of my demise have been greatly exaggerated."

Finally, if I were to search for ammunition for argument in favor of the superiority of tubes I need look no further than the Atmasphere website.

 

[Atmasphere]

You hear from Class D the same “liquidity” that tube lovers hear from tubes?

Exactly.

Ralph,
Two technical questions: what kind of input topology do you use in the balanced mode and what is the switching frequency of your class D amplifiers? BTW, you should get a short code for them!

We probably should. The input circuit is similar to a balanced instrumentation circuit. The switching frequency is about 500KHz. Going higher doesn't seem to win much (you get greater loop gain, so you can run more feedback, but the open loop distortion climbs as well since deadtime is a constant so you need that feedback to counter the increased distortion).

Ahem. if you will allow me to momentarily depart from my claim of gentility.
Are you not a major player in the tube amplification market?

No, as an anaudiophile I don't like it. My disapproval is not prejudicial but is based in fact. I agree, things are going to be different in ten years. Tube amplification has been on the endangered species list for my entire audiophile career. You can get a tube amplifier kit form Walmart for $299. As the saying goes", the reports of my demise have been greatly exaggerated."

Finally, if I were to search for ammunition for argument in favor of the superiority of tubes I need look no further than the Atmasphere website.

I doubt we're considered a 'major player' (thanks, though) although despite our small size we've been influential (for example, balanced line operation for the home is something we pioneered). We've been around a while, which often adds to credibility...

Tubes were declared 'obsolete' back in the early 1960s when germanium transistors were King. Obviously they still had a lot to offer and have now been in production longer than before becoming 'obsolete'. That's not coincidence- its simple economics- tubes were/are providing something that prevented them from going the way of the buggy whip. So people keep buying them. That 'something' is a musical presentation, whether for an audiophile or a guitar player. You love the glow of the tubes because seeing them is part of the realization that good sounds are coming your way. I get it- that's why I delved into tubes over 50 years ago.

With some of the prototypes we had LEDs to show voltage states- when the amp powered up properly all the LEDs were lit. I found that seeing the LEDs gave me the same assurance of musicality that the amber glow of the power tubes did. It seems undiminished by the single LED we have on the front panel right now and the sound is just as involving and musical as before when I had the tubes, but the system is more transparent. Quieter too, which helps if you run horns like I do.

 

[Gregadd]

A bit condescending to suggest the attraction to tubes is the warm glow. I have had and seen tube amplification where you cannot observe the tubes from the listening position. As a matter of fact, I find the tube glow on Steves' LAMM amp somewhat annoying.
But if that's the best you got..

 

[microstrip]

(...) No, as an anaudiophile I don't like it. My disapproval is not prejudicial but is based in fact. I agree, things are going to be different in ten years. Tube amplification has been on the endangered species list for my entire audiophile career. You can get a tube amplifier kit form Walmart for $299. As the saying goes", the reports of my demise have been greatly exaggerated." (...)

I do not have a crystal ball and I do not bet on the future. However, there are some signs we can't ignore, mostly the SOTA high quality of several recent high quality designs that joined the group of top tube designs.

I am a tube audiophile mainly for economic questions - I buy mainly used top high end tube amplification because due to the current low value of tube used equipment I can get a better system using tubes than solid state for the same investment and I am able to diagnose and maintain my tube equipment. But in the used market we also see signs that general interest in tubes is decreasing - the same great sounding units being advertised at high discounts for long times and and no one takes them. Unfortunately, due to world politics, recently tubes rose in price significantly, something that does not help tube future.

BTW1, I am addressing the global amplification high-end market - surely small niches of audiophiles and collectors wanting to pay large amounts for unobtainium or magic tubes will go on active for long.

BTW2, if we want to go DIY we can also build great solid state amplifiers for cheap - many excellent designs are obtainable free at diyaudio.com and I am sure they sound better than amplifiers built with cheap chinese output transformers.

 

[microstrip]

(...) As a matter of fact, I find the tube glow on Steves' LAMM amp somewhat annoying.

Now I see why no one wants to buy my ML3's! Damn tube glow!

 

[DonH50]

...That 'something' is a musical presentation, whether for an audiophile or a guitar player. You love the glow of the tubes because seeing them is part of the realization that good sounds are coming your way. I get it- that's why I delved into tubes over 50 years ago.

A bit condescending to suggest the attraction to tubes is the warm glow. I have had and seen tube amplification where you cannot observe the tubes from the listening position. As a matter of fact, I find the tube glow on Steves' LAMM amp somewhat annoying.
But if that's the best you got..

I do not think that is what he is saying at all. Tubes offer a "musical presentation", and the glow means "good sounds are coming"; it's the sound, not the glow, that's the attraction...

IMO - Don

 

[PYP]

Class D is even finally invading the guitar amplifier market (and not those cheap 'modelling' amps that started to show up about 15 years ago). Audiophiles don't like this fact, but the guitar market has been keeping tubes alive far more so than the audiophile market! As class D invades the guitar market its going to put a huge dent in the bottom line of tube producers. Things are going to look very different in 10 years!

https://www.henriksenamplifiers.com/2019/04/22/amplifying-quality-instruments/

From the article (highlight added):
Tube amplifiers are the oldest of the technologies, and their design is an art unto itself — every little thing matters including where wires are placed when connecting components together. Solid state power amplifier architecture uses a transistor as opposed to a vacuum tube, reducing weight, size, cost and maintenance, but requiring more complex circuits. Most recently, class D amplifiers have become more available and are the predominant amplifier on the market for acoustic instruments as they put out the most efficient power. In the beginning, class D amplifiers had both quality and fidelity issues as well as noise problems when applied to instrument amplifiers (as opposed to consumer audio applications), but those problems are largely a thing of the past.

When designing an amplifier for acoustic instruments, or any instrument where you do not want the signal to contain any distortion, you want as much power as is practical. The more power you have, the more volume and dynamic control you can get from the instrument without mud or distortion; however that brings with it size and weight. Class D amps are the most economical way to do this, but can be missing the analog warmth you get from a tube amp design. As with the preamp, this is where designs need the attention of the designer’s ears as much as anything.

If weight is not so much of a concern, then a well-designed tube amp can deliver a few things that aren’t possible with even the most sophisticated digital circuitry. One of the unique characteristics of vacuum tube technology is that tubes can produce harmonics naturally. Why might this be important, and doesn’t this constitute some type of distortion of the input signal? A purist would say yes – it’s harmonic distortion, but when you take into consideration the loss of the “total” sound and nuances that a single-point pickup system doesn’t deliver to the amp, then it’s a reasonable trade-off.

When playing your favorite acoustic guitar, you’re hearing all kinds of sounds coming not just from the sound hole, but from the sides, the back, the neck and the strings themselves. A lot of the complexity of that sound is lost when you use a single-point, or even a dual, pickup system that samples the sound from a very narrow space on the guitar. Vacuum tubes help by reintroducing some of the harmonics that are lost, giving a very natural sound that has a certain sparkle to it.

 

[Kal Rubinson]

Class D amps are the most economical way to do this, but can be missing the analog warmth you get from a tube amp design.

Vacuum tubes help by reintroducing some of the harmonics that are lost, giving a very natural sound that has a certain sparkle to it.

These statements are based on premises that are not universally accepted. Both the referred to the missing "analog warmth" and the "harmonics that are lost" can be considered as added distortion unless one can demonstrate how and where these " were consistently removed from the original. I am not questioning that some/many do find these differences subjectively pleasing.

 

[Gregadd]

I do not think that is what he is saying at all. Tubes offer a "musical presentation", and the glow means "good sounds are coming"; it's the sound, not the glow, that's the attraction...

IMO - Don

(Text omitted)" the LEDs gave me the same assurance of musicality that the amber glow of the power tubes did" Atmasphere

The speaker is the ultimate arbiter of what he meant. All I know is what he said.

 

[Gregadd]

I am reminded of the development a young boxer who is a legitimate contender for the championship. He must be brought on slowly, choosing his partners carefully to develop his skills. Eventually he may be ready for a championship bout. His success is not just dependent on his skills but is also dependent on the waning ability of the current champion. Father time and combat inevitably take its' toll.
Class D is a contender but is not ready for a bout with the champion. IMO

 

[PYP]

These statements are based on premises that are not universally accepted. Both the referred to the missing "analog warmth" and the "harmonics that are lost" can be considered as added distortion unless one can demonstrate how and where these " were consistently removed from the original. I am not questioning that some/many do find these differences subjectively pleasing.

I wonder where these different listening preferences come from. Do we actually experience the sound differently?

 

[Ron Resnick]

I wonder where these different listening preferences come from.

Audio components don’t reproduce sound perfectly — either the sound of a single acoustic instrument played live in front of us in a small room, or the overall sonic experience we enjoy in the concert hall. We don’t achieve 100% suspension of disbelief while listening to our stereo systems.

Since our audio components collectively cannot re-create the entire experience we feel in the concert hall each of us chooses components that re-create those particular attributes of sound we hear in the concert hall which subjectively maximize our personal suspension of disbelief. Which particular attributes of sound are most important to us as conduits to maximizing our personal suspension of disbelief is subjective. Different audio components will be used by different audiophiles to achieve certain particular attributes of sound.

 

[Holmz]

I am reminded of the development a young boxer who is a legitimate contender for the championship. He must be brought on slowly, choosing his partners carefully to develop his skills. Eventually he may be ready for a championship bout. His success is not just dependent on his skills but is also dependent on the waning ability of the current champion. Father time and combat inevitably take its' toll.
Class D is a contender but is not ready for a bout with the champion. IMO

^That^ is pretty flowery.
(but it is a nice departure from car engine comparisons.)

It's always great when someone says I am right.

I’ll have to take your work on that.
(maybe it’ll happen to me one day.)

I have not heard the amp, so I have no idea what it sounds like. …

Ralph says, “it sounds like one of <his> tube amps.”

 

[bonzo75]

Audio components don’t reproduce sound perfectly — either the sound of a single acoustic instrument played live in front of us in a small room, or the overall sonic experience we enjoy in the concert hall. We don’t achieve 100% suspension of disbelief while listening to our stereo systems.

Since our audio components collectively cannot re-create the entire experience we feel in the concert hall each of us chooses components that re-create those particular attributes of sound we hear in the concert hall which subjectively maximize our personal suspension of disbelief. Which particular attributes of sound are most important to us as conduits to maximizing our personal suspension of disbelief is subjective. Different audio components will be used by different audiophiles to achieve certain particular attributes of sound.

This assumes all visit the concert hall, and then they have similar exposure to gear. Most debates on forums come from people defending their choice compared to what they have not experienced. Even if you find a common base on these two fronts, then comes listening to similar type of music, and even if you find a common base on these three fronts, then comes similar type of recordings. Only if these things are in common and then there is still a difference in choice, can we put it down to different preferences.

 

[christoph]

Now I see why no one wants to buy my ML3's! Damn tube glow!

I for one would love some tube glow.
Neither my KR's nor my Ayon glow really

 

[Gregadd]

[text omitted] Ralph says, “it sounds like one of <his> tube amps.”
Holmz
One of audios greatest contradictions. Tubes are the most criticized and imitated aspect of audio. Often by the same person. Not to mention one of the most diluted phrases in audio.

 

[Ron Resnick]

This assumes all visit the concert hall, and then they have similar exposure to gear. Most debates on forums come from people defending their choice compared to what they have not experienced. Even if you find a common base on these two fronts, then comes listening to similar type of music, and even if you find a common base on these three fronts, then comes similar type of recordings. Only if these things are in common and then there is still a difference in choice, can we put it down to different preferences.

I agree. The lengthier exposition of my point on the dedicated thread about that subject included:

Different audiophiles have radically different levels of high-end audio experience. The different levels of live music experience, the difficulty of even finding components other than popular ones from the most advertised brands, the difficulty of auditioning individual audio components in an analytically valid way, the difficulty of attributing sonic attributes to particular components, etc., all conspire to make this whole endeavor very challenging.

There is a huge problem of people not knowing what they don’t know — and not being introspectively aware of this. And if someone learns a little more, he/she still doesn’t know what he/she doesn’t know. Analytically valid experience to aquire more knowledgeable is not easy to get.

What this means is that there will be greater dispersion in the sounds of the resulting systems then there should be if the average audiophile had a higher level of experience and knowledge. This is why our resulting audio systems sound more different system to system than what we can largely agree we all are hearing in the concert hall.