Class D amplifiers. What's the future look like?

Interesting, thanks.

As to the future, is it just a matter of time until all module makers switch to using ganfet?

I don't think so. In the decade since GaNFETs first showed up, MOSFET producers have improved their craft and are almost as fast- certainly so for any class D circuit. In the meantime, there are other semiconductor types that are already in production and on the horizon.

As to the future, is it just a matter of time until all module makers switch to using ganfet? Is the current state of affairs mature with a much diminished rate of change? Or is there plenty of improvement available in the value equation?

I could go into lots of specifics on ibm, but off topic. My main point is that product life cycle, obsolescence, and innovation require difficult decisions that can determine a company’s future—a general concept far beyond audio devices. Sometimes a bet on the new thing fails, so there is lots of risk and uncertainty. Atmasphere appears to have made a brilliant move here.

Tried my first class D Amp after lightning struck real close and fried my Amp along with a number of other high end components. To date I'm quite happy with the results. 

I think class D is not really taking off yet due to the IMO false impressions provided by commentators who have yet to hear a good quality class D Amp

Some of our older audio brothers get stuck with bias.I  happen to been one of them until misfortune led me in a new direction.

Always wanted to try the class D and now I'm not looking back.

IBM was also the source of the parity bit...

IBM protected their IMS database product and did not innovate with a relational product, and allowed Oracle to take that market.

To be fair, IBM did innovate by inventing relational databases and developing SQL.

So my thought is that calling them digital amps is a reasonable slang and everybody knows what it is referring to.

The distinction here is that digital has specific on and off states that form words (which might be 16, 32 or 64 bits) that represent a value of a voltage. While class D is a switching technology, there are no 'words'; the on and off states are an analog of the input voltage so is considered an analog technology- Pulse Width Modulation goes back a really long way back to the tube era.

All manufacturers have to deal with high risk decisions regarding product life cycle. Do they innovate with product that cuts into sales of cash cow products? Ralph has made his decision. In the last 60 years of computer technology, we see many examples of companies that lost out because they protected existing product. IBM protected their IMS database product and did not innovate with a relational product, and allowed Oracle to take that market. OTOH, they did have enormous success betting the company on system/360.

It sure looks to me like class D will be very disruptive in the amplifier market, but I don’t have a great track record as a future guesser.. ;) 

Always exceptions but Smaller successful older companies are less likely to make radical changes in key product design than larger newer ones. Especially those whose clientele are old school audiophiles.  

Nevertheless, time will tell.

I see these amps as having components: power amp, power supply, case with plugs, some sort of preamp or driver, and maybe adjustable controls. So, many permutations for designers even if they are simply assemblers of oem components.

With computers, I consider the passage of time increases the value equation. This is due to technology improvements and economies of manufacturing scale. I am seeing class D as the same in this respect, but willing to be educated if I have that wrong. Is it safe to say that product will be moving to the faster switching gan devices? I imagine that industry uses millions of times more switching devices, so audiophile class D will benefit from innovations in the larger market.

I also imagine that the marketplace will consolidate in time. It seems like oem components allow one to enter the market with minimal capital investment. Or might it be remain computers where I can pick the components and build my own? Now atmasphere, and I imagine others, will roll their own, so there are sort of two approaches—like proprietary apple or component pc. Well I am not a very good future guesser, so looking forward to the insights of those closer to this. I will not be buying any more class a/b amps, and see this as the technology where the action will be.

Class D is not doing calculations in the strictest sense, so digital is not accurate. It does use fets switching on or off, so a binary state, similar to digital computers. So my thought is that calling them digital amps is a reasonable slang and everybody knows what it is referring to.

@erik_squires Sure- that would work :)

@atmasphere  Should I have said with a comparator??

Sorry, I thought Carver's cube was Class H?

Class D is switching, but there’s no analog to digital/digital to analog process involved. It’s all done with feedback. :)

@erik_squires You can build a class D that is zero feedback as well.

are not longer being criticized as sounding thin or bright...but instead are being praised for sounding like/better than some of the highly regarded class a and class a/b amps.

ICEpower convincingly solved this problem decades ago.  There are some megabuck Class A amps I won't listen to but plenty of ICEpower amps that I will.

Perhaps the GaN amps sound even better, but the truth is we've been blessed with excellent Class D amps for a while. The best comparison I have to triangulate is that I could not tell my Class D from my Parasound so I sold the Parasound.

Then I switched to Luxman which was even better. :) 

Back to the point of reviews needing comparisons...it's not for the reviewer to say that product A sounds better than product B...because after all, it is just his opinion. But when a review goes into some detail comparing and contrasting what they heard; it gives the reader some information with which to triangulate.

You may not like Herb Reichert...but he always gives a bunch of comparisons...and if you can identify with any of them...then you can at least make some inference about how the product "might" sound in your system.  And as we all know, that same product in our system, with our gear and our room may or may not impress.

It appears that the latest generation of class d amps...especially the GAN amps and especially a handful of the better ones are not longer being criticized as sounding thin or bright...but instead are being praised for sounding like/better than some of the highly regarded class a and class a/b amps.

Class D is not digital, per se. Some manufacturers push the envelope though.

Class D is switching, but there’s no analog to digital/digital to analog process involved. It’s all done with feedback. :)

My guess however is that if we include all speaker amplifiers including those used in telephones and TVs and cars and portable Bluetooth speakers and your various talking devices out there that Class D accounts for more than 99% of all amplifiers made today. We in this forum are probably less than 0.1% of the remaining 1%.

"Digital" amplification will eventually dominate both mass market and hi-fi, not that there won't still be products available with traditional topologies. In many respects, this has already happened in the "lifestyle" market at every level, from inexpensive wi-fi active speakers to high-end home hi-fi systems to professional gear. Bang and Olufsen, Devialet, Linn, Peachtree, Bluesound, Technics, Sonos, Genelec, Dutch & Dutch, Avantgarde Acoustics and many other companies are already there. With better performance, the high-efficiency (read: low energy cost) of the digital topologies have a compelling feature set. For those who want tube sound, preamps are already available that deliver that aesthetic that pair well with digital and GaN amps.

Best class D I have heard is Lyngdorf. Not saying much as I haven’t heard a lot of class D but 5 or 6 but no “high end” class d. The Lyngdorf sounds the best out of the bunch I’ve heard without room correction, but with room correction it makes a world of difference, much more so than any small amplifier differences IMHO. Guess where I’m going is I don’t think class D is the future but dsp whether the final output to the speakers is class D, A, AB, H or what have you. 

@fleschler Wrote:

As well as other new applications of technology such as Westminster Labs sliding bias voltage Class A cool running higher power solid state amps?

If it runs cool, it's not true class A. Also, Krell had sustained plateau sliding bias amps in 1992.

Mike

Given the filters and phase shift, does class d design lend itself to mathematical modeling?

Yes. Like anything else though it depends on the quality of your models.

Given the filters and phase shift, does class d design lend itself to mathematical modeling?

@ricevs 

To be honest, I have not put down any amplifiers.  IMO I have not heard one that floats my boat or any of the people I know.  BTW - I have not sold one piece of gear to anyone on Audiogon.  Sorry if I came across this way to you.  I only post my experiences and offer to invite anyone to came an listen to our various systems.  It is a learning experience for us always.  We enjoy meeting new people and hearing new things.  We offer our help and offer to repair and upgrade any component for people who need that type of service.  Not sure what others have "added" to this thread either.  BUT if I came across the wrong way to anyone, then I apologize for that.  That is never my intention.  OK Ric?

As well as other new applications of technology such as Westminster Labs sliding bias voltage Class A cool running higher power solid state amps?   They may well function superior to Class D amps.  

The issue has been for the last 70 years and remains to this day Gain Bandwidth Product; if you plan to run feedback you need a lot of it. Easy to do with class D, very hard with conventional A or AB circuits.

As well as other new applications of technology such as Westminster Labs sliding bias voltage Class A cool running higher power solid state amps?   They may well function superior to Class D amps.  

Current mfg of high end AD amps have a much higher profit margin on their AB design products, as the bulk of R&D expense has been paid for over time.

Once a product is introduced, a good mfg finds ways to lower cost over time to become a low cost - high quality producer, and then can make up for all the R&D going forward. 
 

Having said that, I’d expect many big names are spending at least a few  R&D $ on some Class D product development  

@deep_333 

Thanks for the pics of the Technics innards. Have you hear their newer model G700 Mk 2?

No, i have not...not interested in that one. It has great reviews though. I specifically needed the SU-R1000's 300W into 4 ohms (without space heater amps deployed) for one of my speakers.

Everyone should stop picking on Stevie boy.  I like his vids :-)

@arafiq yours is the best post in this thread so far. 

I’m not sure if it’s prudent to quote Steve Huff to prove your point. 

@deep_333 

Thanks for the pics of the Technics innards. Have you hear their newer model G700 Mk 2?

I have both a Ric Schultz EVS 1200 (based on IceEdge modules with his tweaks) and a stock LSA Voyager GaN 350 (both are dual mono in one chassis). As much as I raved about the EVS, I was smitten with the LSA in the SS rack. Since then I compared my WW exotic cables/XLR with Ali-E faux Nordost Odin 2, which I much prefer.  I have yet to compare amps since replacing my Solid Steel vertical rack with a horizontal 2' x ft 2" X 5' solid wood maple table, because in the process to horizontal I managed to take out one of the LSA modules, forcing me to reinsert the EVS, and must say, Ive been in no hurry to repair the LSA. When I do I will likely send it to EVS for upgrades

The guy reviewed the M-60s in July 21.  Look up the review.....guess what?  In the review of the M-60s he did not even mention any other amp.  So, at least he is consistant....consistantly uninforming.....  He writes very good ad copy.  So, you have no idea how the M60s compared to anything else and then over two years later he tells you the M60s and the GaNs sound the same (from memory).  Gee, that is really enlightening.  Now I know everything there is to know about the possibilities of $6000 amps.....NOT!!!!

What is this mans purpose for reviewing if he is not going to tell you anything worthwhile?  What is the point of ever posting anything anywhere if it is not to actually inform and be of service?

The greatest service I can give you is tell you to go out and listen for yourself because you are NOT going to get any real information from reviews in magazines.  Posts on forums from those that have A/Bed in their own homes are generally more infomative.  Trust yourself.

@atmasphere @lalitk Just to be clear, I found the review informative and loved how he compared the new amps to the M-60 and found the GaN amp to lack nothing compared to an excellent OTL amp (just as Ralph has maintained all along). That part meant a lot and spoke volumes to me. What would’ve made it much more meaningful and interesting would be comparisons to another GaN amp — hell any GaN amp — that would’ve made for a much more effective, informative, and useful review IMHO. But that’s too much to ask from rags like HiFi+ and TAS who’d rather not do all that extra work and expose themselves to any potential accountability — heaven forbid!!!  I’m sure someone soon will write a truly rigorous review that I think a product at the level of Ralph’s GaN amp demands, and I very much look forward to reading that.

A crappy or over hyped review shouldn’t change anyone’s desire to audition or dump a component. A true test of a component is how it sounds (gels) within your system and to your ears.

@lalitk You got that right. If the manufacturer’s, distributor’s, dealer’s or reviewer’s lips are moving, they are lying- we’ve lived with that fact for so many decades, most of us grew up with it. So the only way to know what works, even for the jaundiced ’measurement only’ guys is to take the device home and play it in their system.

I've been running the NAD 268 with my Naim preamp and believe it nicely compliments the latter. The folks at Upscale Audio made the suggestion. 
 

I know there are more unique designs of Class D that have come out recently, so there may be more higher end approaches to Class D in the future.

Looks like I stirred a pot by posting the review..lol! I always taken reviews as a guideline to one’s subjective opinion of a component in their system and personal preferences. Nothing more, nothing less! To @soix point, a comparison with any competitive product would’ve provided a bit more clarity and better understanding on how review sample stacks up against the competition. At the end of the day, it is still an opinion. No two systems are alike, let alone the environment and how we perceive sound…it’s all very subjective and complexed to nth degree.

@atmasphere class D mono’s been on my radar to audition in my system ever since they were announced. A crappy or over hyped review shouldn’t change anyone’s desire to audition or dump a component. A true test of a component is how it sounds (gels) within your system and to your ears.

I think he might need to work on his business model 😁

@soix FWIW Eric uses a set of DeVore Fidelity speakers in his system; the same that he used for the M-60 review. IIRC the o/96s.

Exactly how much time did you waste thinking up and writing that nonsense?

This is how the internals of 1930 computers looked. Compare that to the internals of today's desktops/laptops/servers/super computers

That's it...I just got meself a brilliant business idea. My Class D-iddly amp company will, hereby, be known as "Exo-sphere", i.e., what you hear from my amp will launch you all the way past the atmosphere into the exosphere itself. You will be a lick away from feeling the eternally blakkkk background of space when you listen to my D-iddly amp.

I am gonna buy some kits from aliexpress for a 150 bucks with shipping. I will sprinkle some sodium chloride inside the chassis, light some incense and do a shamanistic dance with it. Thereafter, I will gorilla glue a fake gold label called "Exosphere" on it.

Price = 5700 USD, Exosphere profit per unit = 5550 USD

Thereafter, i will create a hidey account and play the pied piper for my product for a few months. I will pretend that i'm a completely ecstatic customer overjoyed with a Exosphere Class D-iddly amp. I will also pay a couple of other forum pied pipers to sing eternal ecstatic prose about my D-iddly amp.

As all you boys hand me your hard earned cash and empty your retirement accounts, I will laugh all the way to the bank and cash the checks selling Exosphere amps for 5700 a pop. When i see my cousin/my brotha from anotha motha (you know who) snickering away, cashing his checks at the bank, we will hug, hold hands, laugh together and get sloshed at the bar next door to the bank....Oh yeah...baby....Oh yeah...early retirement, here i come....

Ralph mentioned musical instrument amps. I have a 700 watt class d quilter for bass, and it does the job. I think digital for guitar is very much a debate. I think for clean sounds class d is great. The nuance of an overdriven marshall is the sort of thing folks are not quite there on—but as with all things digital—the technology improves over time. Many bar-playing musicians say the guitar amp emulation is not 100% but its close enough to use on stage and not hump heavy amps around.

As to audiophile, my assessment of Ralph over 40 years is that when he says his amp sounds great, I believe him. Over the years many golden ear types thought his amps sounded good, so he must have a good ear or have access to one.Switching technology is a different paradigm altogether, and its not hard to imagine tubes and linear transistors becoming extremely niche. I wish the best for ARC, and I hope they have this sort of thing in development. 

Where is his very precise review of these new mono blocks against all the LATEST class D or otherwise,,,,,done directly in his listening room, RIGHT NOW. NOT there....not there at all. How does the Atmas-sphere compare to a Benchmark amp, to a VTV high powered Purifi or Orhard with all my mods, or to the AGD amps or to Pass amps or to super tube amps in that price range, etc.? How are we to know anything about how it really is and compares with anything already available? All reviews need to be against a known reference in the same system at the same time or it is totally meaningless. The reviewer does not even mention any other amps nor the amps that he currently owns. This review is typical of reviews these days.....completely meaningless.

Agreed. HiFi+ and TAS reviews (among others) are utter garbage because they almost never compare the review sample directly to any competitive product and often don’t even disclose the relevant component in their reference system. As such, their reviews are basically useless and IMHO serve as nothing more than a product advertisement. My theory on this is twofold:

1) Not comparing a review sample directly to a competitive product almost completely absolves the reviewer of any accountability or being pinned down on any assertions he/she makes — they just wax poetic about whatever they “think” or “feel” at the time.  The mags that don’t do comparisons parrot the same line that “it’s unlikely anyone has that specific comparison piece in their system.” Hogwash!!! The fact is humans are very good at relative comparisons and much worse at judging individual things in a vacuum. Relative comparisons are almost always the most important and useful part of any thorough review.

2) It allows the reviewer, and thus the magazine, to spit out “reviews” at a much faster rate as making actual equipment comparisons significantly increases the time to write a review.

When I wrote reviews for Soundstage! a product comparison section was mandatory, and if a reviewer didn’t have or couldn’t get a comparable piece to do a relevant comparison to the product under review they didn’t get to do the review. Period. That, IMO, is the right and only way to do a thorough and meaningful review. Sorry for the sidetrack, but I thought @ricevs hit on a very salient point that warranted some emphasis.

That's a great looking thing, especially with tubes. I wish my next amp would look similar.

I just turned 70 and have vowed never to by audio w equipment I can’t easily lift. I can say that because I’ve been very happy with Be Canto monoblocks for many years (ref 300s and now ref 500s.) No going back to the heavy and hot power amps I used before. 

The whole idea that quality is measured in pounds…is ponderously asinine.

Ah, ever better, with tubes 😁

But, when i just look at his D with the chassis open, it ain’t looking like much to me

This is how the internals of 1930 computers looked. Compare that to the internals of today's desktops/laptops/servers/super computers

As has been mentioned in the many responses; execution is everything.  Whether you agree with this notion or not, the proof is in the hearing.  Listening to the latest technologically advanced amplifiers from Mola Mola (the new Perca stereo amp or Kula integrated amp) and you begin to dispel concerns over amplifier output class.  They are transparent, 3D, dynamic, and oh so musical.    

This is now just turned into another thread on Class D.....rather than what the future of it is.  The Atma-sphere amp may be the best $5400 class D amp you can buy....or maybe not.  The review has nothing to do with that.  He compares (BY MEMORY) to an older tube Atma-sphere that he reviewed some time ago.  What the heck does that have to do with anything?  Where is his very precise review of these new mono blocks against all the LATEST class D or otherwise,,,,,done directly in his listening room, RIGHT NOW.      NOT there....not there at all.  How does the Atmas-sphere compare to a Benchmark amp, to a VTV high powered Purifi or Orhard with all my mods, or to the AGD amps or to Pass amps or to super tube amps in that price range, etc.?  How are we to know anything about how it really is and compares with anything already available?  All reviews need to be against a known reference in the same system at the same time or it is totally meaningless.  The reviewer does not even mention any other amps nor the amps that he currently owns.  This review is typical of reviews these days.....completely meaningless.  It is if Ralph himself wrote the review.....it is simply ad copy.  I am not saything that is what happened....just that "WHERE IS THE BEEF?"...This review is spam....he he.  High end audio has NO REFERENCE......there is no agreed upon anything.  Nothing like car hot rodding.....you can simply measure car performance on the drag strip.  There is no drag strip in audio.....It is every man for himself.....beating on his chest that he knows something.  Pretty silly, really.  Here I am beating on mine....he he.

What if some magazine got 10 of the reputed best amps all around $5000 and compared them all in several systems over several months and gave you their TOTALLY honest opinion about them......This would never happend as the magazines are all about money.  In fact, Stereophile has banned me from making comments on line after reviews because I would come in and describe how the product just reviewed could be made better....not as a put down.....just as information for the betterment of sound.  They don't want the manufacturer to be shown that.  They want the manufacturer happy, so they keep paying for ads.  Stereophile makes no money on subscriptions....its all about the ads.  Sad, but true.  This is why you have to listen yourself and make your own mind up.  Stop being so outer directed.....YOU KNOW what the truth is.  But, you have to seek it out for yourself.  Magazines will not give you truth....for the most part they are ad copy.  A lot of reviewers do not want to compare to older or different things because they are not getting paid much or very little so they want to keep all avenues open to everyone in case they want to buy something from a manufacturer later on at half price (which is what reviewers usually pay).  Audio is a game.....played by people who are enthusiastic about audio....BUT, are also commited to their own DESIRES (money and saving money and prestige).   

Love does exist.....but it is not generally shown in audio reviews. 

I believe the future of class D is digital amps like the Levinson (Mark Daniel) and Peachtree GaN1, the Technics amps, the Lyngdorf amps, etc.  And bi and tri amping with digital amps is what we will see more and more....for that is the ultimate.

I just looked inside the Technics biggy and I see some things I could do to make it sound noticeably better......not going to do it.  But, there is way more to be gotten than what is avaiable stock now.  I could mod the Atma-sphere amps to sound way better too......You will see....er hear....as time goes on.  Again.....as Karen sang "We have only just begun".  Audio keeps getting better and love grows and grows......Life is great!

when i just look at his D with the chassis open, it ain’t looking like much to me.

Class D, done properly, is never going to look like much. Its very different from a tube amp in that regard!! The biggest issue class D has to contend with is noise generation; to that end the module has to be as small as possible to minimize parasitics caused by stray inductance (and at the frequencies involved, a lead of a part easily causes problems...). Because we are using GaNFETs, which don't require large heatsinks, the heatsinks (which are machined to 1 mil tolerances) are beneath the module and serve also as its mounting. So ya, not looking like much 😉