I went from Class D to Luxman A/AB - And most of what you think is wrong

I would say that’s a 10/4 good buddy............

@georgehifi, so I take it your not talking from actual experience of GaN or top end class D. 

You say you can’t hear it that’s fine then live with it, but stop starting new Class-D threads to look for confirmation/cred from everyone about how good it is compared to the best linear amps.

Says the man who has to, absolutely HAS to jump into every thread that includes mention of Class D.


Unlike you George, I can use specific examples and talk about exactly what I do and do not hear. Others who have or are enjoying Class D can also cite specific examples of what they bought or what they listened to.


Some may not like the Class D amps they have heard. That’s fine. The whole point of this article was that I was happy with a specific type of Class D but went to Luxman anyway and that the collection of Achilles’s heels you carry around with you, like a homeless man and his shopping cart, have not made it into my listenable space in a very long time.

tweak1, you two are not that far off on your love of all things audio.  I am uncharacteristically interested in how you like your EVS 1200.  As I know you will, give your initial impressions, but be sure to circle back after you have a month or two under you belt for the longer term view, after the honeymoon is over.  Thanks in advance. George 

George, you continually exhibit selective memory. Your ad nauseum mantra, makes me wonder WHY you persist?

WE ALL GET IT: you’re not a fan. Neither are you ’converting any of us, so what’s your point?

Oh, and FYI, ALL genres of amps have Achilles Heels.

Previously, I pointed out the high cost of 300 wpc+ UNLESS going class D. GaN may solve the issues deter you, but they will also be uber expensive, at least for the foreseeable future

I have owned quite a few SS and tube amps as well as class D over the last 10 years, none compared to either my Audio Alchemy DPA-1 or the PS Audio M700s @ 350 wpc MSRP $2995 the pair. And I have previously stated I have a RicSchultz EVS 1200 on order; 600 wpc, dual mono, highly tweaked board and chassis for $2200

But only George can hear it.

Not just me sunshine, everyone else that hears something wrong in the upper mids/highs with Class-D, you just don’t hear it, and choose to ignore that very big fact.
https://live.staticflickr.com/3666/33726831296_436f60f683_b.jpg

You say you can’t hear it that’s fine then live with it, but stop starting new Class-D threads to look for confirmation/cred from everyone about how good it is compared to the best linear amps.
When that old Class-D technology moves forward instead of sideways with the new GaN technology and make use of the 3 x higher switching speeds available, then it will compete with the best linear amps.

I’ve said it before, when Class-D can finally drive a pair of speakers like my big ML’s, Wilson Alexia, Alexandria or Watt/Puppies to their very best like linear amps can, then it will be time to sell my inefficient boat anchors, to purchase them.

Don’t need to, they are all variations on a technology that has an achilles heel that can’t be fixed.

But only George can hear it.

So, @georgehifi you have compared GaN with other class D amps?

Once again in case you missed it, or just inconspicuously trying to shill your own wares

• Don’t need to, they are all variations on a technology that has an achilles heel that can’t be fixed.
• Even Mark levinson tried to get around the problem with these massive monoblocks with very robust "higher order" output filters to get rid of the switching noise as to not effect the phase shift into the audio band, but it flopped also. https://ibb.co/YdVr6Wr
• The only way is much higher switching frequency with low order filters that are also set much higher, aka Technics SE-R1 because of the GaN technology.

Cheers George

Hi,
While I love the small footprint, cool running, low current draw of Class D, there is one compelling reason I will not own one: as an audio repairman for almost 40 years (McIntosh Labs, Nagra, dCS, Musical Fidelity), I cannot even begin to repair a Class D amp.
Class A or AB  for me for the foreseeable future.
Cheers!Steve GeorgeNashville

So, @georgehifi you have compared GaN with other class D amps?

cleeds, you are absolutely right.  I apologize to the group for my stupid remark.  Pain meds and keyboards do not a match make. 

As far as I can tell high end audio is more of a rat race than ever as there are many more manufacturers looking for a piece of the pie. The marketing is getting progressively more obnoxious.  Kids appreciate good sound like the rest of us. They go to concerts and are quite capable of discriminating between great and not so great sound. But, life in general is more expensive than ever and megabuck HiFi systems are not on their priority list. Later in life they are sure to join in as finances allow. They are also more likely to include theater in the equation as well as vinyl which I find very interesting. I think we are analog creatures at heart. There is nothing like the warm glow of tubes. That is an instinctive attraction. 
As far as class D amps are concerned I think TACT was on the right path with an amp that encoded in pulse width modulation and sampled at 90 meg. They were very clean sounding amps with solid bass but they did not like reactive loads at all. I have never heard a Rowland amp but obviously someone is paying close attention to build quality. I have no doubt that Class D amps will become very competitive with other amps in regards to sound quality. Back in the late 60s we all thought that SS amps were garbage because they were. A decade or two later and they came into their own and many of us think they are superior. The efficiency of class D is what I find so attractive. Turning money into heat is counter productive especially when you spend more money air conditioning it out of the house. 
After all it is all about enjoying the music right? Silly. We all love music or we would not be doing this. HiFi is all about reproducing the music but to what standard? There really is not one or rather we all have our own standard which evolves over time. But I can say that in the presence of a truly great system jaws drop and there is very little criticism. I love it when my jaw drops.

@glennewdick -
I disagree with your assessment about Rowland’s amps and comparing them to the numerous brands that simply take an existing Class D module with its stock SMPS and stick it in a cheap chassis. JR designs and builds his own proprietary SMPS which are actually very expensive to implement correctly and then integrates those power supplies with various Class D output stages which he selects for their sonic performance. His SMPS outperforms most linear power supplies and avoid creating the AC line noise which lesser designs inject on the power line. His chassis construction is exceptional, with most models having aluminum billet chassis which are expertly machined and masterfully finished.
Granted his amps are not inexpensive, but their level of engineering and build quality are exceptional as is their sonic performance. Quality of that level comes at a price... of course there are cheaper implementations of Class D amps which are quite popular but are not competitive with the performance of the Rowlands despite some circuit similarities. There is a market for both types of products, more value oriented amps and cost no object designs for more demanding audiophiles.

And this, folks, is why this hobby is in a death spiral. Stupidly expensive gear with adherents that can "hear" all sorts of artifacts and distortions ...

Nice try, but high end audio is not in a "death spiral." It's evolving, which is exactly what keeps it from being in a death spiral. If you don't like audiophiles, then maybe you shouldn't hang around here where audiophiles often congregate.

And this, folks, is why this hobby is in a death spiral. Stupidly expensive gear with adherents that can "hear" all sorts of artifacts and distortions which they focus on to the detriment of enjoying the music. Had a very interesting chat with my 30 year old software engineering son. He questioned why anyone would spend the kind of money high end companies charge to listen to music. His generation looks upon this hobby as a total waste of time and resources, and that is the future of audio. Go to RMAF or any of the other big shows and take note of what you see. For the most part, a bunch of 60 something white guys with more money (sometimes) than sense. Class A, Class A/B, Class D, Class G, ad nauseum.

Not sure I agree with all of this. Go to Munich and watch for the young families with strollers and under 30 years men and women. Its quite different in Europe and Asia!

Regarding distortions- anyone can hear distortion since the ear uses higher ordered harmonics to sense sound pressure. Traditional solid state amps are well-known for making such harmonics and being quite audible as harshness and brightness. This is why tubes still exist!

Kids these days buy LPs- hence the revival of the medium- kids keep the music industry alive! Whether they are conscious of it or not, they are hearing something in the LPs that they like as opposed to digital. You don't have to know anything technical to understand that.


I see people of all ages at RMAF and AXPONA but admit that younger people are a minority. What works for kids is the same as it was for us old people- that its relevant to our lives. When they hear music reproduction that sucks they just stick with their earbuds. When the reproduction is good, then they dream of the day when they can have that sound at home. The latter is what happened to a lot of us older audiophiles. The shows are there so the public (and hopefully kids) can feel the dream.


Regarding class D, the carrot on the stick is that a class D output section does not have the same sort of artifact that is imposed by the output section of a traditional solid state amp. The distortion made by the amp is thus caused by the encoding scheme, whatever is needed to drive the encoder (and some comparitors have pretty low input impedances, so this is not a trivial matter) and how much deadtime is needed to keep the output transistors happy. As switching transistors get faster (the current embodiment of speed being GaN devices) the deadtime needed is reduced and with it the distortion of the amp.

Everything evolves. early transistor based amps from the 60's-70's were sort of horrid, it took them a decade to really flush out the transistor amp sound and another decade to sort out the different types of transistors and class types now we have another new class type and its finally being fleshed out and evolving. 

 yes I agree time to move past the class war and just enjoy the music. There is horrid class A amps and great ones just like there is horrid class D amps and great ones.

 I'm just hoping class D comes to a time when its not a few manufacturers making modules that everyone else plunks in their own case and marks it up ridiculously (i'm looking at you Rowland).  

Time for the innovators to take over. (cherry is one of these I think)

I love all classes and SS and tube I consider myself a moderate and just want to enjoy the music. 

great thread by the way. 

@georgehifi please try class D amps by SPEC, Audio-Nec and Mola Mola before commenting further.

Don't need to, they are all variations on a technology that has an achilles heel that can't be fixed.
Even Mark levinson tried to get around the problem with these massive monoblocks with very robust "higher order" output filters to get rid of the switching noise as to not effect the phase shift into the audio band, but it flopped also. https://ibb.co/YdVr6Wr

The only way is much higher switching frequency with low order filters that are also set much higher, aka Technics SE-R1 because of the GaN technology. 

Cheers George   

@rocray, my experience is only with Hypex based class D amps and these have been very reliable.

@georgehifi please try class D amps by SPEC, Audio-Nec and Mola Mola before commenting further.

How is durability/reliability of class D vs other technology? I know this is a rather broad question. 

Tim, now that's funny, Maybe he has alien hearing

I actually feel bad for georgehifi.

He has so many real or imagined allergies and afflictions to exceptionally good class D amplification that he’s unable to derive the same pleasure from hi-end sound quality at such affordable prices like so many others like us enjoy on a daily basis.

Poor George,
Tim

you started the personal slurs again

You meant to type "provided  historical context."

@georgehifi what class D amps have you heard?

Many as I’m in the industrie, the only one that impressed so far has been the BelCanto 600M’s, but only when they drove a very expensive two way, that had a very benign 6ohm load in the upper mid highs, because they used I believe the top Raven ribbon tweeter. The same amp let me down severely, when it tried to drive my highly modded ML Monoliths which has the latest same as the Neolith panels.

Cheers George

@georgehifi what class D amps have you heard? 

Hello all,

I only have one room for A/V enjoyment.  My amplification must serve 7.1 surround and 2.1 stereo.  I think the sound emanating from my HK is no compromise in either circumstance.  I just hope HK is not going flush it all down the toilet as they appear to be migrating to "lifestyle" (aka Sonos, Bose, etc.) mediocrity.

https://www.digitaltrends.com/gadget-reviews/harman-kardon-avr-3700-review/

" Its clean power delivery and dynamic capabilities were quite impressive for a class D receiver, and its rich, powerful, and refined sound reminded us of what a good, audiophile-quality amplifier sounds like."  

I like what I have and will probably remain so until I get another bug up my butt telling me I need to upgrade.

@georgehifi 

With all due respect, what's good for the goose is good for the gander.

Look at what you posted, you started the personal slurs again Iric with your post, not me.

" I was really worried that Goerge would have gotten too old and tired not to raise the same tired and irrelevant tropes"

So just suck it up sunshine without the slurs that start these confrontations. And come back with some thing technical or useful against what I’ve posted, not just a derogatory slur, your getting good at those, if you've got nothing then don't say anything. 

Erik instead of burying your head in the sand about the problems that Class-D has had since it’s inception, with switching frequencies+filters,

The man who simply refuses to listen to any view but his own would like to claim I buried my head in the sand.

No, George, my original post was all about a progressive view point towards Class D amplifiers. Your view is from the 1980s and has moved nowhere. As we’ve discussed with embarrassing regularity, your claims of the superiority of Class A/B amplifiers over Class D based on measurements alone has no justification in terms of audibility of any amplifier made in the 21st century.

My claims are from personal experience, along with those of other audiophiles who have visited. You can complain about the sound quality of specific amps, but the trope is decrepit.  I am however astonished at your powers of necromancy in bringing them up over and over again despite so many positive reviews from Audiogoners to the contrary.

mark levinson class d!

George

I too am a fan of certain class D amps, with plenty I haven’t heard. Ive owned quite few SS amps from tube/ss hybrids to AB to the class A Kinergetics KBA 75, which to this day was the best amp Ive heard here, My system then consisted of Genesis 5s made especially for Harry Pearson. I don’t recall what the front end was. The KBA was the only amp of the many I tried that grabbed ahold of the Gen5 mid/tweeters and made them perform to their potential. Sadly, one afternoon I was comparing power cords, and apparently didn’t let the caps drain. When I plugged the new one in sparks flew and it was toast. KBA was out of business then so... I don’t recall the other amps I tried, but none made the grade. The guy I bought them from had BAT monos, but I never heard his system.

The point Im trying to make is all types of amps have issues and I could hear the issues with the many amps Ive owned. Happily, I have never been exposed to what the frequency band distortions sound like that some here cannot get past. Perhaps if someone were to take me into their lab and play the distortions for me, I might change my mind, but thankfully, I don’t hear it, and thankfully I can buy a Rad EVS 1200, 600w, dual mono with highly tweaked boards and chassis, among other thoughtful tweaks for $2200. Ric Schultz, the brains behind this amp, mentioned that the new Van Alstine DVA 4/2 stereo amp sounded really good, and could be tweaked to sound even better. Probably a great bargain at $3699, but comparing watts to watts his V 600w monos start at $2499 per. Anyway I already pushed my budget to $2200, so Im just glad I don’t hear what annoys some of you

Erik instead of burying your head in the sand about the problems that Class-D has had since it’s inception, with switching frequencies+filters, embrace instead the new GaN technology, that when used correctly as Technics has done with the SE-R1 can address those problems forever. At the expense of a little bit of heatsinking.

This then will put Class-D up with the best linear amps into the very hiend, instead of half of the audiophile not accepting it at all, because they hear things in the mids and highs you obviously can’t.

same tired and irrelevant tropes

Only in your own mind Erik, as you continue to start Class-D posts to get others validate your Class-D views and purchases because you can't yourself.  

I’m making blanket statements about all of class D for a reason.

To punctuate my original post: Bunk.

This example suggests that it is far better to form opinion after listening to particular amp than making blank statements about whole class D.

I’m making blanket statements about all of class D for a reason.

A strong, stable, intelligent set of reasons. As in none of them ..class D, that is...performs. Nether in the listening, the engineering, or the execution (build).

It is still a turbo on a Honda civic --- trying to pose as a formula one car. As that is it’s origins. It was never meant for formula one use, never designed for it, at all. Never intendedd for it, no part of it's engineering or potential in build approaches what is required for such highfalutin use.

When the market involved finally has one that is engineered and manufactured properly, that works in a way that satisfies how the ear works and functions---- then get back to me (us).

Maybe in about 3-5 years. Maybe. No such luck yet.

When I started this thread I was really worried that Goerge would have gotten too old and tired not to raise the same tired and irrelevant tropes he always does, but whatever held him back before, it's good to see he's recovered and fit as a fiddle, cutting and pasting the same things from the dozens of other threads on the subject.

This example suggests that it is far better to form opinion after listening to particular amp than making blank statements about whole class D.

Measurements don’t lie, there is considerable phase shifts down to 5khz if the output filter is set too low to minimise switching frequency being too high in amplitude. And if the filter is set too high the the switching frequency become very apparent riding on the back of 1k square waves. (re: the links I posted above)

The only remedy is to raise the switching frequency by at least 3-4 x and set the fiter much higher so it can do it’s job, as Technics has done to 1.5mHz with the SE-R1. And this can be done using GaN Technology.

From EPC’s Steve Collino, past inventors of the Power Mosfet and now the new GaN Technology.

"Our GaN FET will give an even higher performance difference compared with MOSFETs in both sound quality and efficiency at 1.536 MHz."

He said then, they have to be heaksinked, as Technics had to do.

Cheers George

Thanks @melvinjames, Honestly I think it's just 30 year old biases. We might as well be complaining that solid state gear isn't as reliable as tubes again.

Best,
E

Yes 90kHz is a little better than 60 or 70kHz, but not by much - leaving noticeable phase shift in audio band. I’m not even sure that this phase lag is a problem, since speaker, being inductive at higher frequencies, shifts phase forward. Lamm Industries Signature Monoblock ML3 has only 30-40kHz bandwidth (that should introduce substantial phase shifts in audio band), but was highly praised by Stereophile: "It was quiet, fast, detailed, dynamic without reservation, transparent, airy, and extended on top".
This example suggests that it is far better to form opinion after listening to particular amp than making blank statements about whole class D.

my old class D amp had 60kHz bandwidth

Yeah and it probably looked like this on a 1khz square wave
https://cdn.head-fi.org/a/2780785.jpg
It all about how much switching noise is let through without causing phase shifts down into the audible range.
And that why 1.5mHz is good for switching frequency, because it can be filtered out well above and not have any phase shifts down into the audible frequency band, like all the others do.

Here is the Anthem Statement M1 claimed frequency response to 45khz look at it’s square wave, not pretty, in fact if you saw this on a linear amp you’d have to say it’s broken. https://www.stereophile.com/images/1212AM1fig02.jpg

Cheers George

You’ll just have to look at what Technics did on the SE-R1, no complaints about it becoming an RF transmitter using normal non shielded speaker cable, just praise for it's good sound.

Perhaps because they raised frequency response only to 90kHz, implying about 50% increase in switching frequency (my old class D amp had 60kHz bandwidth).  They could go higher with GaN Mosfets but stopped at only 90kHz possibly because of RF radiation.  Rowland's integrated Daemon has 70kHz bandwidth at 10x more output power (1500WPC @ 8ohm).  AFAIK it uses plain non-GaN Mosfets.

That’s true, but it might open another bag of worms. In current designs filter leaves about 1% of switching noise on the speaker cable.

As you say "it might"
You’ll just have to look at what Technics did on the SE-R1, no complaints about it becoming an RF transmitter using normal non shielded speaker cable, just praise for it's good sound.
Maybe they’ve done some fancy RF output filter as you can see (orange) the amplitude and cycles of ringing are much reduced as well the square wave itself is far better.
https://ibb.co/MpmqzGt

Cheers George

That’s true, but it might open another bag of worms. In current designs filter leaves about 1% of switching noise on the speaker cable. It is only small percentage but of very high value, reaching 100V - making it approx. 1V peak switching noise on the cable. It can be easily seen with the scope. The only reason why it does not radiate is the fact that 500kHz wavelength is 600m. Antena becomes very ineffective below 1/10 of the wavelength - in this case 60m. There will be still some, very small electromagnetic radiation but it should not be a problem. Increasing switching frequency, let say 10x will make this antena "dangerous" at 6m, producing some radiation even with regular speaker cables. It is possible to filter it better, but it would lower bandwidth resulting in phase shift in audio band, that we want to avoid. Perhaps compromise is somewhere in-between, increasing switching frequency only 2-3x while still enjoying improved linearity thru reduction of dead time.

I can hear that residual noise as a forming of hash and noise around every single transient, micro transient and complex harmonic.

Basically, class d loses the idea of high fidelity as all of high fidelity happens in that exact spot mentioned. the rest of the signal is almost meaningless.

So i spend a lifetime trying to fix that tiny little bit and class D comes along and maims to death the very part I and other in the realm of high fidelity seek and fight for.

This noise can be mistaken by some people as detail, when it is actually noise and out of band, out of time ---- added distortion and noise.

worst of all, in the modern realm of digital audio, A/D and D/ A systems also cause massive disturbance right in this area of signal.

This means you now have an entire generation of people who have NO IDEA how good analog can sound and generally does sound, when this part that digital does wrong, is absent in the signal.

Then, this lack of knowledge and exposure to what analog does right, is then aided and abetted by the hash and junk that Class D adds in on top of that. this whole mess is somehow regarded as muddy and fatiguing ’detail’, where it all sounds the same. Because it is.

this is like some freaking nightmare world. You’re kidding me, right?

@toetapaudio, I would love to audition those brands. I firmly believe class D will be the norm sooner than later. I heard the mola’s a couple times, at audio shows, which is far from perfect for listening.

For example, I’ve read that GaN transistors are capable of switching so fast they literally eliminate dead-time and any resulting distortion caused by it.

If a designer believes that, its simply because the encoding scheme and related parts are slow enough that the circuit may not need any dedicated deadtime circuitry since its literally built in due to those slower parts.  Or- the designer added enough heatsinks so that the GaN devices stay cool even though there is shoot-through current.

Your need to go on ad nauseum without actually addressing the points I made is actually kind of like watching a fetish in public.

What point did I not address?

after reading George's reply to whomever wrote about GaN switching speeds:

"This is so correct, but so far it seems that only one has utilized this ability to take the higher switching speed up to 1.5mHz available with GaN (2.5 x higher than present), and that is Technics with their SE-R1, it does mean they had to use heatsinks to get it."  

After reading this I am wondering what part this feature on the EVS 1200 product page would play in better sound, and is the a relationship between it and switching speed

EVS Product Page

I install my own custom input circuit on the module for way lower distortion.

Not if you talk to a designer of a class D amp :)

Your need to go on ad nauseum without actually addressing the points I made is actually kind of like watching a fetish in public.

I believe after a trusted friends opinion on how the Technics SE-R1 sounded, that you may as well stay with what's used now with the old Mosfet technology and 600k switching speed, if the GaN's higher switching speed transistors are used WITHOUT utilizing it's higher 1.5mHz switching speeds and filtering that their capable of.
It would be a waist sonically to use them and not fully utilize their performance advantages.
(Bit like never going over 2000 revs in a Ferrari)

Cheers George  

Also it’s not that the higher switching speed alone make for the good sound it gets, it’s also that the "low order output switching noise filter" that all Class-D’s have to use, can now also be taken up 2.5 x higher, this then has no effects now down into the audible range, like the filters today do, which can cause phase shifts down to 5khz, and why many complain about something not right in the upper mids/highs.

That's true, but it might open another bag of worms.  In current designs filter leaves about 1% of switching noise on the speaker cable.  It is only small percentage but of very high value, reaching 100V - making it approx. 1V peak switching noise on the cable.  It can be easily seen with the scope.  The only reason why it does not radiate is the fact that 500kHz wavelength is 600m.  Antena becomes very ineffective below 1/10 of the wavelength - in this case 60m.  There will be still some, very small electromagnetic radiation but it should not be a problem.  Increasing switching frequency, let say 10x will make this antena "dangerous" at 6m, producing some radiation even with regular speaker cables.  It is possible to filter it better, but it would lower bandwidth resulting in phase shift in audio band, that we want to avoid.  Perhaps compromise is somewhere in-between, increasing switching frequency only 2-3x while still enjoying improved linearity thru reduction of dead time.