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Class D: Turns Out it Does Suck!


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5 hours ago, Ralf11 said:

I wonder why Audio Research dropped class D ??

Relevance?

Do you also wonder why other brands have picked up Class D? 

 

Neither is actually relevant.

Companies make decisions like that all the time. Lot of different reasons. Sometimes they drop a technology and then readopt it afterwards.

 

Sometimes different companies disagree, imagine that. None of it proves anything. Expert amp designers also disagree. I've yet to understand how cherry picking the expert who goes along with your opinion proves anything - it's not as if all respected amp designers agree about class D. 

Same thing with all other types of audio components. 

Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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5 hours ago, Ralf11 said:

I wonder why Audio Research dropped class D ??

I'll ask the dealer next time I'm there.  Bel Canto had to change from making there Ref1000 amp to Ref600 amp because the manufacture no longer made that internal board.

Computer setup - Roon/Qobuz - PS Audio P5 Regenerator - HIFI Rose 250A Streamer - Emotiva XPA-2 Harbeth P3ESR XD - Rel  R-528 Sub

Comfy Chair - Schitt Jotunheim - Meze Audio Empyrean w/Mitch Barnett's Accurate Sound FilterSet

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17 hours ago, GUTB said:

Even though the weight of evidence does seem to suggest class D sucks, I'm still listening to counter opinions.

 

As always it is matter of system synergy. My Lyngdorf amplifier (okay, not completely traditional class D) is indeed a bit sterile and analytic when I keep everything in the digital domain. BUT the combination with a very musical DAC (like my Chord DAVE), the very good ADC module in the Lyngdorf and off course good cable matching the sum of components leads to a very, very musical, transparent and resolving end result.

Streamer dCS Network Bridge DAC Chord DAVE Amplifier / DRC Lyngdorf TDAI-3400 Speakers Lindemann BL-10 | JL audio E-sub e110 Head-fi and reference Bakoon HPA-21 | Audeze LCD-3 (f) Power and isolation Dedicated power line | Xentek extreme isolation transformer (1KVA, balanced) | Uptone Audio EtherREGEN + Ferrum Hypsos | Sonore OpticalModule + Uptone Audio UltraCap LPS-1.2 | Jensen CI-1RR Cables Jorma Digital XLR (digital), Grimm Audio SQM RCA (analog), Kimber 8TC + WBT (speakers), custom star-quad with Oyaide connectors (AC), Ferrum (DC) and Ghent (ethernet) Software dCS Mosaic | Tidal | Qobuz

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10 hours ago, Ralf11 said:

I wonder why Audio Research dropped class D ??

Probably poor sales.  Since there are lots of sub $100 Class D amps and alot of negativity on the internet surrounding them, I would imagine it's very difficult to sell them at ARC prices.  

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I bought eight Hypex UcD700HG modules (and HxR regulators) when they first came out, for a fully active setup - four per channel. I used linear PSUs with massively over-sized trannies - one per module. They were replacing a pair of Pass Labs X600 monos I was using in my passive setup before going active. The Hypex modules measured superbly and were the only practical solution I could come up with at the time.

 

I have to say, the Hypex modules put me off class D for life - a totally bland and dead sound to my ears. Perhaps newer class D amps (Hypex and others) sound better, but they'd have to be so much better for me to even consider them for a sub, let alone anything else. In any event, having been through so many different types of speakers and amps over the years, I know I'll be sticking with horns and SETs from now on.

 

Mani.

Main: SOtM sMS-200 -> Okto dac8PRO -> 6x Neurochrome 286 mono amps -> Tune Audio Anima horns + 2x Rotel RB-1590 amps -> 4 subs

Home Office: SOtM sMS-200 -> MOTU UltraLite-mk5 -> 6x Neurochrome 286 mono amps -> Impulse H2 speakers

Vinyl: Technics SP10 / London (Decca) Reference -> Trafomatic Luna -> RME ADI-2 Pro

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1 hour ago, The Computer Audiophile said:

I've spent a lot of time listening to class A, class A/B, and class D. In my experience class D amps have the biggest range between implementations. Meaning, some of them are really good while others are horrible. The class A amps I've had and heard, are all really good. But, almost nobody build class A anymore so the sample size is rather small. Plus, who is going to go to the expense of building a bad class A amp. 

 

One issue with class D is the marketing. Manufacturers have been saying for a long time that class D has finally caught up with A/B or finally overtaken A/B etc... In many cases this hasn't been true. These statements have only hurt the class D technology rather than help it. For example, I had a manufacture over to my place within the last year, who claimed its class D amp could compete with or better the best class A/B. I said, fine, let's put it to the test. After listening to my Constellation Audio Inspiration Mono amps he said wow that's awesome, now let's put my gear into the system. After a few seconds his tail was between his legs. He was surprised at how much better the Constellation amps were than his. I think he was caught up in his own marketing and couldn't envision the outcome of the test beforehand. I knew what the outcome would be because I had already done it before he arrived. 

 

My bottom line is that I'm more skeptical about class D than any of the other technologies. This is mainly because of all the promises we've heard over the years and all the less than stellar results we've heard to back up those promises. 

I don't know what class D you heard, but I'm assuming it cost less than your $20K pair of monos. So basically, if he had been more modest with his claims, something like "my Class D is as good or better than any Class A/B amp near its' price", you would have been fine with both the amp and the claims.

 

I don't claim there's a Class D amp as good as the best of A/B amps, like your Constellation. 

I do claim there are some NCore, Nuprime, PS Audio, and ICE implementations which are as good or better than anything close to them in price, and they also give you  more power.

I heard the active Kii Three system, powered by a proprietary version of NCore (made specifically for these speakers/drivers). That amplification wouldn't be beat by conventional amps I know of that cost even several thousand each. And there are 6 of them in each speaker.

I've heard some of the  other recent stand alone Class D amps I mentioned above, and they would also fall in that category, 

Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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Has anyone listened to well broken-in Jeff Rowland 825 or 925 amps?  Ncore technology, but implementation is everything.  

Pareto Audio AMD 7700 Server --> Berkeley Alpha USB --> Jeff Rowland Aeris --> Jeff Rowland 625 S2 --> Focal Utopia 3 Diablos with 2 x Focal Electra SW 1000 BE subs

 

i7-6700K/Windows 10  --> EVGA Nu Audio Card --> Focal CMS50's 

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4 minutes ago, firedog said:

I don't know what class D you heard, but I'm assuming it cost less than your $20K pair of monos. So basically, if he had been more modest with his claims, something like "my Class D is as good or better than any Class A/B amp near its' price", you would have been fine with both the amp and the claims.

 

I don't claim there's a Class D amp as good as the best of A/B amps, like your Constellation. 

I do claim there are some NCore, Nuprime, PS Audio, and ICE implementations which are as good or better than anything close to them in price, and they also give you  more power.

I heard the active Kii Three system, powered by a proprietary version of NCore (made specifically for these speakers/drivers). That amplification wouldn't be beat by conventional amps I know of that cost even several thousand each. And there are 6 of them in each speaker.

I've heard some of the  other recent stand alone Class D amps I mentioned above, and they would also fall in that category, 

 

I don't disagree. 

 

I heard the Kii system at Axpona. I liked what I heard, but the room was noisy so I couldn't really make any judgements. I can wait for @mitchco to get the Kii. He is on the list to get them, but the list is long. I put in another good word for him to get them sooner.

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Thanks Chris, I am looking forward to reviewing the Kii Threes. The Dynaudio Focus 600 I reviewed use Class D amps and I remember them sounding very good. I have not seen any comments to say otherwise... In the pro audio world, virtually every brand (e.g. Genelec, Focal, KRK, JBL, PreSonus, Neumann, etc.) have active studio monitors powered by Class D amps. On the pro audio forums I see very few negative comments on the sound of Class D with these monitors

 

In my case, I run a large 2 way active monitor setup with a Class D power amp driving the woofers up to 630 Hz and digital XO over to a Nelson Pass Class A SE amps, as the compression drivers have much lower power requirements. Sounds great to my ears.

 

For sure, a few years back or so, there seemed to be quite a bit of variability in the sound of Class D amps, but that variability seems to be becoming less of an issue today. Not saying it is a completely solved tech, but certainly less variable. I wonder if @dallasjustice has some thoughts on his Class D amps he is using with his JBL 4367's...

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Another meaningless anecdote.  I had been using mid-90's vintage Krell KAS-2 monoblocks in my system, exceeded only by the KAS-1 at the very top of their lineup at that time.  Class A, of course.  KAS-2 MSRP then - $22,000 the pair.  

 

About 7-8 years ago, I auditioned against the Krells in my own home a bunch of different hi quality amps  - classes A, A/B and D.  I did not like the Bel Canto or other B&O ICE-based Class D's back then, for example.  But, my favorite amp by a fair bit was a little-known, direct from the mfr. Spectron Musician III Mk. 2 Class D, which I thought sounded better than all of them, including my Krells.  

 

I sold the Krells, and I am still the very happy owner of the Spectron. $4k MSRP, by the way.  Spectron's founder, John Ulrick, died about a year or so ago, though the company goes on. He developed the first switching amp in  audio history when he worked for Arnie Nudell at the old Infinity, when it was a primo audio company.  Quite possibly, though, the Spectron is now outclassed by much newer and better sounding Class D's.

 

My take is amp class matters not at all sonically. Implementation matters much more.

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11 hours ago, firedog said:

Relevance?

Do you also wonder why other brands have picked up Class D? 

 

Neither is actually relevant.

Companies make decisions like that all the time. Lot of different reasons. Sometimes they drop a technology and then readopt it afterwards.

 

Sometimes different companies disagree, imagine that. None of it proves anything. Expert amp designers also disagree. I've yet to understand how cherry picking the expert who goes along with your opinion proves anything - it's not as if all respected amp designers agree about class D. 

Same thing with all other types of audio components. 

 

not sure why most of your verbiage seems aimed at my post

 

If I had to guess why Audio Research dropped class D  it would be lack of fit with a storied tubed electronics line and consequent low sales.

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6 minutes ago, Fitzcaraldo215 said:

Another meaningless anecdote.  I had been using mid-90's vintage Krell KAS-2 monoblocks in my system, exceeded only by the KAS-1 at the very top of their lineup at that time.  Class A, of course.  KAS-2 MSRP then - $22,000 the pair.  

 

About 7-8 years ago, I auditioned against the Krells in my own home a bunch of different hi quality amps  - classes A, A/B and D.  I did not like the Bel Canto or other B&O ICE-based Class D's back then, for example.  But, my favorite amp by a fair bit was a little-known, direct from the mfr. Spectron Musician III Mk. 2 Class D, which I thought sounded better than all of them, including my Krells.  

 

I sold the Krells, and I am still the very happy owner of the Spectron. $4k MSRP, by the way.  Spectron's founder, John Ulrick, died about a year or so ago, though the company goes on. He developed the first switching amp in  audio history when he worked for Arnie Nudell at the old Infinity, when it was a primo audio company.  Quite possibly, though, the Spectron is now outclassed by much newer and better sounding Class D's.

 

My take is amp class matters not at all sonically. Implementation matters much more.

 

Saying "amp class matters not at all sonically" is a position that seems really hard to justify when class D amps output waveforms like these:

 

316NADfig02.jpg

 

Note that Stereophile stopped doing those measurements without using the Audio Precision low-pass filters to produce a waveform that looks less embarrassing. But even with the cheating, we can see class D just can't seem to handle it.

 

That's because the signal that goes INTO class D is NOT the signal which comes OUT. What comes out of class D is a modulated and filtered facsimile. That's why it has been pointed out that class D is mathematically, physically inferior to linear amplification. Of course, there are benefits to this trade-off, as always -- because class D doesn't amplify the input signal, it's also not amplifying unwanted components of the input signal. 

 

Then there's bandwidth. While the switching frequency of the NC1200 is 500 KHz. Meanwhile, Krell Evolutions have a usable bandwidth of 300 KHz...Goldmunds go up to 3 MHz (+/- 3dB) ... not even on the same planet.

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1 hour ago, Fitzcaraldo215 said:

Another meaningless anecdote.  I had been using mid-90's vintage Krell KAS-2 monoblocks in my system, exceeded only by the KAS-1 at the very top of their lineup at that time.  Class A, of course.  KAS-2 MSRP then - $22,000 the pair.  

 

About 7-8 years ago, I auditioned against the Krells in my own home a bunch of different hi quality amps  - classes A, A/B and D.  I did not like the Bel Canto or other B&O ICE-based Class D's back then, for example.  But, my favorite amp by a fair bit was a little-known, direct from the mfr. Spectron Musician III Mk. 2 Class D, which I thought sounded better than all of them, including my Krells.  

 

I sold the Krells, and I am still the very happy owner of the Spectron. $4k MSRP, by the way.  Spectron's founder, John Ulrick, died about a year or so ago, though the company goes on. He developed the first switching amp in  audio history when he worked for Arnie Nudell at the old Infinity, when it was a primo audio company.  Quite possibly, though, the Spectron is now outclassed by much newer and better sounding Class D's.

 

My take is amp class matters not at all sonically. Implementation matters much more.

 A related anecdote.  Class D amps do become more iffy depending upon the speaker partnered with them.  The output filtering can interact with some loads.  Really no worse than high output impedance SETs and triodes just different.  As switching frequencies increase it likely will be a lesser problem.  With some speakers now it is no problem. 

 

Funny you mention the Spectron.  Was the first switching amp I tried and it was stereotypically horrendous with my speakers.  Some of the best most solid bass you would find, midrange of middling quality and everything else was horrid.  So it put me off such amps for awhile.  Tripath and ICE amps work fine with my speakers. 

Bel Cantos have varied as they use different switching modules though they also manage something of their house sound mixed in as well.  As I think good amps have no sound that has bothered me a little that those amps have a sound.  It is a finely chosen sound at least.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Re: Genelec - have another look, they moved to Class D amps, including their top of the line studio monitors: https://www.genelec.com/studio-monitors/sam-studio-monitors/1236a-sam-studio-monitor

 

Genelec presented a feasibility study about moving to Class D in 2013: https://www.genelec.com/sites/default/files/media/About Us/Academic_Papers/2013_rose.pdf

 

If I find some time, I will put my Class D amp on the bench and get screen shots from a scope as I am set up to test amps. Will compare it to the NP Class A.

 

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4 minutes ago, Fitzcaraldo215 said:

Ok, so you show a measurement of a mystery class A amp of unknown provenance and you insist they all do that, i.e., they are all the same, they are all no damn good.  They can all be judged simply,  just like people can by the color of their skin or their ethnicity. Class A = bad and you have the proof! 

 

So, you have your mind made up.  Why then are you jerking us around? Go for tubes, man.  Or, blow your money on Class A and pay the monthly electric bills.   Ain't it great that we have choices? While you are at it, you'd better start stepping back big time from all digital audio, because the output from that is a only a "modulated and filtered facsimile" of the analog input. 

 

By by the way, if you know of an amp where the input us the same as the output,  go for it! Except, no one else would call such a zero gain device an amplifier. Also, if you know of an amplifier that adds zero distortion and noise while it adds gain, go for it, man.  You have got a winner.  We mere mortals here do not know of such a device.

 

My dog and all the bats in the neighborhood also gotta have that 3MHz frequency response, which no mikes pick up, is not on any recording and which no speaker reproduces.  But, hey, if it works for you, knock yourself out.  I am quite sure you can hear the difference, unlike the rest of us.

 

 

 

As usual, no actual counter-argument, just class warfare.

 

The measurement is from the NAD M22. But please, find a single class D amp that Stereophile measures that looks much different. They used to show measurements with the low-pass filter off, which produces waveforms like this:

 

1212AM1fig02.jpg

 

Anthem Statement M1.

 

Amplifier bandwidth is beneficial to the audio band.

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The signal that goes INTO class AB or class B is NOT the signal which comes OUT.   What comes out of class AB or class B is a modulated and filtered facsimile with cross-over distortion.  That's why it has been pointed out that class AB or class B is mathematically, physically inferior to linear class A amplification.  Of course, there are benefits to this trade-off, as always.

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24 minutes ago, Ajax said:

From Wikipedia:

 

".... a troll is a person who sows discord on the Internet by starting arguments or upsetting people, by posting inflammatory messages in an online community with the intent of provoking readers into an emotional response,[3] often for the troll's amusement."

 

When you reread the title of your thread "Class D; Turns Out It Does suck!" in conjunction with the comments from the amp designers, the above statement is a good fit. Inflammatory headlines is the oldest trick in the book for selling newspapers, especially when the editor is scratching for some worthwhile news or an interesting story line. It is the reason why Trump's mantra of "Fake News" has gained such traction with the public.

 

Several of the designers you quote actually state that a combination of A & D class amplification has great potential. It is still early days. Just look at the development in DAC technology over the past 25 years since the advent of digital audio. 

 

I have a Devialet 200, which parallels a low-wattage Class-A amplifier with a high-power Class-D amplifier dedicated to providing current, in a hybrid arrangement, which one reviewer stated "delivers the sweetness and harmonic complexity of solid-state Class-A circuits, with the bass power and control of good Class-D designs." To my ears, and many many others, it sounds wonderful.

 

I also have a Nord Hypex NCore NC500 amplifier driving a pair of ATC STM 19 speakers. Does it with ease.

 

FWIW, here's some advice. Making ridiculous assertions to attract attention, complete with "exclamation mark!", will loose you credibility very quickly,  There are many here at CA with greater knowledge and experience than you so if you want to gain respect on this forum I suggest you read more and write less and cut out the "look at me".

 

I suggest you take 24 hours to think about what I have written before pressing reply.

 

Thank you for the subjective review of the Devialet. Class D is definitely not in "the early" days any longer.

 

I stated that it turns out that class D sucks. To support this position I quoted some of the greatest living amp designers. It's an appeal to authority, but as I am not an authority myself I think that's okay! Calling class D "just as good" as linear circuits is actually the fake news. Alternative facts.

 

Nelson Pass diplomatically stated that a $10 bottle of wine can compare with $100 wine -- especially considering the price. It's a nice way of saying, NO, class D isn't competitive in the high end.

 

I think there is an unfortunate class warfare aspect to this topic. People with their DIY amps and sub-$2k amps want to believe that they compete with linear amps that cost many times more.

 

 

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9 minutes ago, GUTB said:

 

Thank you for the subjective review of the Devialet. Class D is definitely not in "the early" days any longer.

 

I stated that it turns out that class D sucks. To support this position I quoted some of the greatest living amp designers. It's an appeal to authority, but as I am not an authority myself I think that's okay! Calling class D "just as good" as linear circuits is actually the fake news. Alternative facts.

 

Nelson Pass diplomatically stated that a $10 bottle of wine can compare with $100 wine -- especially considering the price. It's a nice way of saying, NO, class D isn't competitive in the high end.

 

I think there is an unfortunate class warfare aspect to this topic. People with their DIY amps and sub-$2k amps want to believe that they compete with linear amps that cost many times more.

 

 

So, buy a Pass XA series and be done with it.  But, why are you jerking us around and trying to impress us with quotes out if context from your favorite amp designers of yore?  You know it all, so why try to dazzle us?

 

Ignore list!!

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3 minutes ago, GUTB said:

I stated that it turns out that class D sucks. To support this position I quoted some of the greatest living amp designers. It's an appeal to authority, but as I am not an authority myself I think that's okay! Calling class D "just as good" as linear circuits is actually the fake news. Alternative facts.

 

If you had asked or quoted great class D designers like Bruno Putzeys, Peter Lyngdorf, the guys at Devialet and people like Eelco Grimm (Grimm Audio) as well, you would have presented a much more weighted starting point. I find it quite naive to posit such a theorem in a forum with critical members like CA is.

Streamer dCS Network Bridge DAC Chord DAVE Amplifier / DRC Lyngdorf TDAI-3400 Speakers Lindemann BL-10 | JL audio E-sub e110 Head-fi and reference Bakoon HPA-21 | Audeze LCD-3 (f) Power and isolation Dedicated power line | Xentek extreme isolation transformer (1KVA, balanced) | Uptone Audio EtherREGEN + Ferrum Hypsos | Sonore OpticalModule + Uptone Audio UltraCap LPS-1.2 | Jensen CI-1RR Cables Jorma Digital XLR (digital), Grimm Audio SQM RCA (analog), Kimber 8TC + WBT (speakers), custom star-quad with Oyaide connectors (AC), Ferrum (DC) and Ghent (ethernet) Software dCS Mosaic | Tidal | Qobuz

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