Looking For Class D Candidates

[Tuckers]

To which tube amps have you compared them directly in your own system?

It's been a long time since I had a tube amp. The last was Shindo Sinhonia push pull f2a monoblock amps. So no valid comparisons.

 

[tima]

Any decades-long tube amplifier manufacturer who is so determined to torpedo his own tube amplifier business by dissing tubes in favor of his Class D amps must be onto something.

This is quite an offensive over-reach. You can recommend the Class D based only on a couple hours of listening but there's no need to, imo, mischaracterize Atma-Sphere. The company continues to sell and support its full line of tube amplifier and preamplifiers. From my discussions with Ralph he never suggested he was out to "torpedo" his own designs. His OTL and OCL products continue to provide top quality sound. Class D is an expansion of his product line.

His stated rational for building the Class D amps is a belief that tubes will continue to be less frequently adopted and thus become less available. That view, so he explained, comes not from the audio world but from performing musicians who use electronic amplifiers to make their music (eg. Fender, Marshall, Mesa/Boogie, etc.) That group uses far more tubes than the audio world. So, as I said, he is forward thinking. "Tube amplifiers are on borrowed time." We'll see if that turns out to be true, but it is not a "diss" or an admonition to stop using tubes.

Imo, the rationale for Class D when compared to tube amplifiers is not superior sound quality. "Foremost in rationale may be Class D's higher efficiency of operation—it uses considerably less energy than Class A or even Class A/B. Because of its efficiency it produces less heat and does not require the massive heat sinks found on less efficient amps. It does not require big transformers and capacitors. That means you can fit one in a much smaller and lighter package." They are also less expensive to build which appeals to those looking for lower entry price to an audio system.

 

[Holmz]

This is quite an offensive over-reach. You can recommend the Class D based only on a couple hours of listening but there's no need to, imo, mischaracterize Atma-Sphere. The company continues to sell and support its full line of tube amplifier and preamplifiers. From my discussions with Ralph he never suggested he was out to "torpedo" his own designs. His OTL and OCL products continue to provide top quality sound. Class D is an expansion of his product line.

His stated rational for building the Class D amps is a belief that tubes will continue to be less frequently adopted and thus become less available. That view, so he explained, comes not from the audio world but from performing musicians who use electronic amplifiers to make their music (eg. Fender, Marshall, Mesa/Boogie, etc.) That group uses far more tubes than the audio world. So, as I said, he is forward thinking. "Tube amplifiers are on borrowed time." We'll see if that turns out to be true, but it is not a "diss" or an admonition to stop using tubes.

Imo, the rationale for Class D when compared to tube amplifiers is not superior sound quality. "Foremost in rationale may be Class D's higher efficiency of operation—it uses considerably less energy than Class A or even Class A/B. Because of its efficiency it produces less heat and does not require the massive heat sinks found on less efficient amps. It does not require big transformers and capacitors. That means you can fit one in a much smaller and lighter package." They are also less expensive to build which appeals to those looking for lower entry price to an audio system.

In his defence; I think it was an attempt at humour.

 

[tima]

In his defence; I think it was an attempt at humour.

strange -- no one was laughing

 

[Holmz]

strange -- no one was laughing

There are not a lot of laughing scenes in that movie.
I suppose sometimes it can be hard to know when it is funny without a laugh track to queue us…

If it was intended as humour, then maybe he should have put in a to help convey it?

 

[Hear Here]

I think anyone interested in a Class D amplifier should start with Ralph's Atma-Sphere Class D amps. Any decades-long tube amplifier manufacturer who is so determined to torpedo his own tube amplifier business by dissing tubes in favor of his Class D amps must be onto something.

I don't think Ralph is torpedoing his tube amp business, but he's more likely trying to stay in business! Tube stuff is on the decline because of its high initial cost, high running costs and a sound that can now be matched or bettered by the best Class D technology - at much lower cost. Other tube brands will struggle to survive if the doggedly ignore Class D.

I have Ralph's Class D monos and a Purifi Eigentakt amp. The latter technology is currently the best mainstream Class D, but there are dozens of amps built cheaply using the Purifi Eval(uation) board that is offered at low cost to DIY builders. Best not go that route, but look at the big brands (NAD, T+A, etc) that build under license with superior components and use carefully designed and matched ancillary parts such as power supplies.

I am still undecided whether I prefer the Atma-Sphere over the NAD Master Series that uses Purifi. Both are extremely good amplifiers. The NAD was chosen after a year of home evaluation with numerous amps in the £3-8K range of Class A, AB and D. All were bought or borrowed after I decided to move away from SETs, but only if I could find an ss amp that would match or better the listening enjoyment level of the SETs

 

[Ron Resnick]

This is quite an offensive over-reach.

Thank you for your critique. I am a huge fan of Ralph personally and of his tube electronics.

I edited my original post to distinguish between Ralph's OTL amplifier business and the SET designs he rails against. It was my unintentionally offensive mistake to have failed to make that critical distinction in the first place.

In December of last year I wrote to Ralph:

1) Respectfully, as a manufacturer of tube electronics your position that you don't like SETs is detrimental to your business model. It is not good for you to be a proselytizer against SET. This should not be your focus.

2) Focus on showing why OTL is great, not why SET is bad.

From my discussions with Ralph he never suggested he was out to "torpedo" his own designs.

How old were you when you had your humorectomy?*

*I know that a humorectomy is not an actual surgical procedure.

His OTL and OCL products continue to provide top quality sound. Class D is an expansion of his product line.

I fully agree on both points. It was exactly on these points that I encouraged Ralph numerous times over e-mail and telephone to respond crisply to Mike Gefteas' original (graciously later corrected) suggestion last December that Ralph had stopped making tube amps.

 

[bonzo75]

This is quite an offensive over-reach.

The hyperbole police are permitted to

 

[Anton D]

This may come as a shock to some -- it certainly came as a shock to me -- but I am prepared to recommend a Class D amplifier. I listened over the weekend for several hours to Laiv Class D GanFET amps. These things are $5,400 a pair, about the size of a container of Pepperidge Farm cookies and weigh only a few pounds.

Don and I went to Jim Yager's house. Jim has the giant PBN M777 loudspeakers, ARC REF 10 line stage and Soul Note phono/optical, Acoustic Signature Montana turntable and DS Audio optical cartridge.

Jim feels and Don feels that these tiny Class D amps are the best amplifiers Jim has had in his system, beating vintage Mark Levinson, ARC amps, Jadis JA30s, Luxman, Canary and Lamm hybrids.

I am reserving my judgment until I get a direct comparison with the Lamm hybrids, which heretofore are my favorites in Jim's system. But I agree with them that these cheap, tiny amps sound inexplicably good.

That will be a cool thing to read about as you get more time listening!

 

[Tuckers]

. So, as I said, he is forward thinking. "Tube amplifiers are on borrowed time." We'll see if that turns out to be true, but it is not a "diss" or an admonition to stop using tubes.

Ralf has stated many times that his Class D measures better and sounds better than his tube amps, sometimes in this forum. I don't think that is torpedoing his designs, there are those that will just continue to like the distortion profile that tubes provide, compared to the (smaller in measurements) distortion profile of his Class D. He has also stated that the distortion artifacts left in his Class D tend to be 2nd order and lower level harmonics, much like tubes. I am not dissing tubes in any way here, we have to accept some distortion in an amp, we just choose the profile that to our ears lets more of the music through.

 

[Atmasphere]

I do have quite a bit of personal experience with really good sounding power amp design by now. That said, of the several things that generally kind of hold class D back is, many designs use a generic (more or less) SMPS PSU. I really wish that was sufficient to get the best audio results, but unfortunately the audible reality is that it simply isn't. If it was, believe me we'd all be using it as it has a lot of other very significant advantages. To the lynch mob who want to rail about the above statements, my only response is, please first try it for yourself and find out. In your favorite amplifier deign try both an audio SMPS and a good linear PSU, then report back and share your own findings.

Our class D amps use linear power supplies.

His stated rational for building the Class D amps is a belief that tubes will continue to be less frequently adopted and thus become less available. That view, so he explained, comes not from the audio world but from performing musicians who use electronic amplifiers to make their music (eg. Fender, Marshall, Mesa/Boogie, etc.) That group uses far more tubes than the audio world. So, as I said, he is forward thinking. "Tube amplifiers are on borrowed time." We'll see if that turns out to be true, but it is not a "diss" or an admonition to stop using tubes.

I feel a need to clarify this a bit.

I heard a class D amp at AXPONA about 8 years ago that I felt was operating in a territory that previously was only the pervue of tube amplifiers. On that account I came to the conclusion that if we didn't get a handle on class D we'd get left behind.

Our goal was to build a class D amp that sounded as good or better than our OTLs. Since OTLs are some of the most transparent/revealing tube amps ever made this might have seemed like a big ask. On top of that the amp had to have the smooth character you expect of an excellent tube amplifier- no harshness.

We felt it would send the wrong message to the marketplace if we fell short of those goals. But when the amps were finally ready we had surpassed them- the class Ds are relaxed and we get high consistency when people compare to tube amps (as we have) in that the class D is more 'focused' so its easier to tell what's happening in the rear of the sound stage; IOW more transparent/resolving.

But because the amps are not bright some will say they lack 'sparkle' (which is a term I really dislike). IME 'sparkle' is a brightness brought on by higher ordered harmonic distortion- such amps tend to get harsh at higher volumes. The bandwidth we're getting is well past what anyone can hear. So tonality on the top is not a function of frequency response. Its coming from a lack of unmasked higher ordered harmonics.

I did not set out to kill our tube amp business (recently our MA-2 OTL has been selling quite well; mostly to the ESL loudspeaker market). I like tubes- they are fun and have a kind of gothic nature to them not unlike prewar motorbikes. We just introduced a little 5 Watt integrated amp recently that IMO easily takes on SETs of similar power. And I'm working on other tube amp designs too. But I've no illusions; its just for fun, since when it comes down to it the class Ds are consistently more musical.

Getting a class D amp to sound like an excellent tube amp is allowing them to invade the musical instrument market. I've been watching that happening for the last 15 years. Many guitar players rely more on their effects pedals for their 'sound' than they do the amps, which is quite different from 20 or 40 years ago. They still avoid solid state because they can be to shrill or biting. But if the guitar amp is relaxed like tube guitar amps are, it will be a big change because a Fender Twin weighs about 70-80 pounds while a class D guitar amp head of the same power might be only 15 pounds. That's a huge deal if you can get the sound you want as well. At 3:AM when you're done with a gig you notice things like that when moving out of the venue.

The musical instrument market sales of vacuum tubes is 10-20x larger than the entirety of high end audio. If class D makes a serious encroachment into that market its going to hurt tube suppliers. That, and the fact that we can build class D amps that sound better than tubes is why I think tube amps are on borrowed time.

 

[Argonaut]

Meh !!!

 

[Republicoftexas69]

strange -- no one was laughing

I did and at your post too.

 

[Republicoftexas69]

Our class D amps use linear power supplies.

I feel a need to clarify this a bit.

I heard a class D amp at AXPONA about 8 years ago that I felt was operating in a territory that previously was only the pervue of tube amplifiers. On that account I came to the conclusion that if we didn't get a handle on class D we'd get left behind.

Our goal was to build a class D amp that sounded as good or better than our OTLs. Since OTLs are some of the most transparent/revealing tube amps ever made this might have seemed like a big ask. On top of that the amp had to have the smooth character you expect of an excellent tube amplifier- no harshness.

We felt it would send the wrong message to the marketplace if we fell short of those goals. But when the amps were finally ready we had surpassed them- the class Ds are relaxed and we get high consistency when people compare to tube amps (as we have) in that the class D is more 'focused' so its easier to tell what's happening in the rear of the sound stage; IOW more transparent/resolving.

But because the amps are not bright some will say they lack 'sparkle' (which is a term I really dislike). IME 'sparkle' is a brightness brought on by higher ordered harmonic distortion- such amps tend to get harsh at higher volumes. The bandwidth we're getting is well past what anyone can hear. So tonality on the top is not a function of frequency response. Its coming from a lack of unmasked higher ordered harmonics.

I did not set out to kill our tube amp business (recently our MA-2 OTL has been selling quite well; mostly to the ESL loudspeaker market). I like tubes- they are fun and have a kind of gothic nature to them not unlike prewar motorbikes. We just introduced a little 5 Watt integrated amp recently that IMO easily takes on SETs of similar power. And I'm working on other tube amp designs too. But I've no illusions; its just for fun, since when it comes down to it the class Ds are consistently more musical.

Getting a class D amp to sound like an excellent tube amp is allowing them to invade the musical instrument market. I've been watching that happening for the last 15 years. Many guitar players rely more on their effects pedals for their 'sound' than they do the amps, which is quite different from 20 or 40 years ago. They still avoid solid state because they can be to shrill or biting. But if the guitar amp is relaxed like tube guitar amps are, it will be a big change because a Fender Twin weighs about 70-80 pounds while a class D guitar amp head of the same power might be only 15 pounds. That's a huge deal if you can get the sound you want as well. At 3:AM when you're done with a gig you notice things like that when moving out of the venue.

The musical instrument market sales of vacuum tubes is 10-20x larger than the entirety of high end audio. If class D makes a serious encroachment into that market its going to hurt tube suppliers. That, and the fact that we can build class D amps that sound better than tubes is why I think tube amps are on borrowed time.

My Canor A1 2.10, we have the well-known Hypex power unit in Class D powered by a filtered and tuned linear power supply. It is a great sounding hybrid integrated that is on par with my Qualiton X200.