Class D: Turns Out it Does Suck!

[esldude]

I have owned product from five of those guys, and have lots of time listening to a sixth.  I respect them all as they represent quite a large body of knowledge. 

 

Yet I have this feeling you have just quoted the pronouncements of dinosaurs who ruled the last paradigm of audio. Only Jeff Rowland has caught wind that the times are a changing.

 

Had I been there I would have asked, for $3000 can you build an amp better than class D for the same money with comparable power?

[esldude]

15 minutes ago, GUTB said:

 

Hey, here is what several top amp designers think.

Check out these screwed up measurements.

 

"Ignore the troll". Lol.

 

Look. I've listened to various class D products including the latest Pascal module. It's true modern class D has come a long in my experience from "unlistenable" to "excellent with a few deadly flaws". But, in the end of the day, it doesn't matter how resolving and controlled it is if its filters destroys soundstage depth and it struggles with musicality. I wish I could just buy a sub-$2000 amp that I can pick up with one hand and be happy with it. I'm sorry I have certain expectations from speaker listening.

Of course you are listening thru colored glasses, you keep comparing them to a highly linear SET.  Now talk about your oxymorons. 

[esldude]

If anyone doubts the OP is trolling look at the tags he applied to his thread.

 

SAVAGE

FACTS

BRUTAL

CLASS D

 

Yep he's trolling. 

[esldude]

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.

[esldude]

Just going by the time, one is a 1 khz square wave and the second is a 10 khz square wave.  So not at all comparable.  We don't know the voltage level. 

 

And the reviews confirm this.  Both graphs here are small signal waves.  No 1 khz wave shown for the HC A.  The 10 khz small signal wave for the Fisher is so rounded it looks closer to a funny sine wave.

[esldude]

17 minutes ago, Ralf11 said:

 

it Looks GROOVEY - that's all the counts!

 

 

(yes - it is a $125 Chinese made integrated (tune/SS) with Bluetooth) from monoprice.com

And endorsed by the Wall Street Journal.  Stereophile and TAS eat your heart out.  Do they have a recommended components issue of the Journal?

[esldude]

As long as we are posting deceptive squarewave graphs out of context, I offer this small signal 10 khz square wave:

 

 

Thoress 300B monoblocks which according to JA:

 

Overall, the Thöress 300B monoblock measures well for a SET amp.

 

It manages almost (not quite) 10 watts at 3% THD.  So I am not sure it could do anything other than a small signal square wave.  Price is only $12,995 per pair. I guess these don't suck like some stupid class D designs. 

 

They didn't blow much of the budget on beautiful build quality either. Kept it where it counts....producing the kind of special distortion people crave. 

 

 

[esldude]

3 hours ago, STC said:

 

IME, I find Class-D CrownXLS is better at driving the difficult ESL Sound Lab than my other audiophile approved Amp. I am not naming the amp because mine was rather outdated and the newer ones probably are probably better. Having said that, I was told that Sound Lab uses Crown as their in-house Amp, a fact I came to know after I acquired the Crown amp which I bought to check whether a 300 Watter would be a better replacement to my 250W Amp.

I have heard quite a variety of amps on my or other people's Soundlabs.  The second best at driving them with aplomb was a bridged pair of Classe 25's.  That is right about 1 kilowatt of honest real power on them.  It gave them some dynamic and other qualities not usually heard from them.  The Wyred4Sound ST500 amp I use is better than that on them.  I don't know if it would play them as plainly loud, but in other ways it is faster, better, tighter and simply cleaner sounding.   Better than other large amps I have heard on them, better than push-pull triodes of large size and better than a horrendously expensive OTL that I heard on them.  At the time I was also replacing a well regarded 250 watt class A/B amp

 

I had no idea Soundlab uses Crown amps.  

 

[esldude]

4 hours ago, STC said:

 

I was using Classe 25. The highs were missing. I thought I needed more power and all I could barely afford was the CA-2300. I am a Classe fan and reluctant to go for other brand. And I prefer new. 

 

I got the Crown XLS 2000 ( although the current model is XLS2002) to check whether the 300W was enough. 

 

Yes, I had all the initial thin sounding feel with the Crown but the longer I listened I noticed the highs were correct.  

 

I couldn't do blind test because I know the difference in the highs so I have to rely on others who are not familiar with the brands. 

 

I think I also posted the C Vs C video here. Sound Lab informed me the reason for the missing highs were due to the output impedance. Apparently, Crown is lower. 

Yes the Soundlabs are very low impedance in the treble and the Crown's much lower output impedance.

[esldude]

2 hours ago, semente said:

 

The best thing to do, environmentally speaking, is stop producing new gear and only buy used.

There's enough audio equipment around for everyone.

 

If you think that it takes over 2.5kL of water to produce a white t-shirt...

That's not so bad on the t-shirt.  It probably only take about another 200 liters to wear it out. 

[esldude]

3 hours ago, jabbr said:

So for those of us who spend a fair amount of time in a heated, rather than cooled, environment, would a Class A amp with an efficient radiator system be acceptable? Or must we just shiver  

Well it is true the waste heat is 100% efficient as heat.  Then again if outdoor/indoor temperature differentials are favorable a heat pump can do better than that.   The energy cost of pumping heat can be less than the energy cost of generating heat.  If you know what I mean.  Even though my engineer friend who works with those and refrigeration systems wouldn't be happy with how I have stated it.

 

So in such a case, it still would be better to have class D amps, and run the heat pump a bit more environmentally at least.  Mentally it could be a different story.

[esldude]

14 minutes ago, Audiophile Neuroscience said:

 

can you characterize the sound of your A/B tube amp compared to your Pioneer solid state Class A amp compared to say any Class D amp or is it not that simple. Might a well implemented class D sound better than a class A or do you feel there are inherent and audible limitations?

I use a pure class A amp which also has variable bias settings for A/B operation. I've never heard a class D amp that I like but not saying they cannot sound fantastic.

I'll give my subjective impressions though you weren't asking me. 

 

Class D when good sounds fast and powerful.  And it doesn't seem to care if you use very nearly all of that power as the sound quality stays consistently clean at all levels. It is capable of depth and space when its on the recording.  It doesn't create it however leading some to think it clinical. 

 

Spectral amps have the speed of class D and maybe more.  They sound powerful and relatively unaffected by how much you use, but not quite to the extent Class D does. 

 

Good class A amps shouldn't care about power used, but they do seem to fog up just a bit when much of it is used. Sometimes that fog is heard as additional space and dimensionality.  They don't fall apart the way some class A/B amps do when pressed into using lots of the available power.  Some of the finest A/B amps don't leave much to choose vs class A. 

 

Push-pull tube amps are a different thing altogether much more effected by what they are connected to.  You'll just have to listen and hear it for yourself. 

[esldude]

1 minute ago, sandyk said:

 The only way that is likely to happen is when they are almost at their designed power specifications and there is a large increase in distortion products as they enter clipping. This is similar to what you may hear with some digital gear where distortion or low level wideband noise appears to result in false treble.

As someone with ESL's, I can probably manage that with most amps.  I'm rather sensitive to even a little bit of actual clipping however.  I don't drive my amps to clipping.  I hear others do it all the time without noticing and it drives me up the wall. 

 

I once had an SS McIntosh amp with the Power Guard circuitry.  A 752 which is 75 wpc.  It was marginal for my Acoustat speakers.  Power Guard was a comparator which would activate if distortion reached .5% and was optically coupled into the amp circuitry to reduce peaks and prevent actual clipping.  Driven ridiculously hard it would act as a compressor. 

 

If you pushed it some getting the indicators to illuminate it would fog up some, and you could manipulate volume to get a handle on that sound.  This minor fogging if you barely activated the circuit is rather similar to what I hear with class A amps under heavy load.  And not dissimilar to powerful push pull tube amps under heavy load.  

 

So the fog I am referring to is not like the wideband brightening of poor digital gear.  Nor an amp driven to actual clipping. 

[esldude]

19 minutes ago, Audiophile Neuroscience said:

 

I'm not sure what you mean by fog up Dennis. It certainly doesn't seem to suggest a positive trait despite maybe resulting in extra space and dimensionality.

 

My experience of many A/B amps is that they sound a little leaner and can impart an impression of more etch/outline and detail leading to descriptions of clinical if you don't like it and spacious ,detailed an open if you do like it. It can also give the impression of more rhythmic drive I think if transients are crisply reproduced

 

Many Class A otoh sounds often warmer and fuller relatively speaking sometimes described as more musical if you like it and less detailed if you dont.Sometimes being described as more "tube-like"

 

So its all subjective obviously. You may value different qualities or 'colors' over others

 

These are also definitely just generalizations or overall character impressions and so I have no fixed belief one amp will be better than another (except arguably with expectation bias).I suspect it all comes down to implementation and quality of components,  etc

 

My current amp has massive power reserves (500,000uf toroidal transformers) and for my taste is the best I have heard to date at just sounding neutral, getting out of the way of the music, imparting no signature.I have no idea if that has anything to do per se with how it 'uses power'.

 

 

I've told before of doing serial amp testing.  One amp is loaded with power resistors and feeds the amp on the speakers.  Few amps are without character.  I've actually not done that test with any class D.  Spectrals can be inserted or removed and you will not know it.  According to the Swedish AES some Brystons can manage the trick.  Usually you won't need blind testing the differences are clear sighted as long as levels are matched. 

 

If some audio club wanted a great meeting, doing some serial testing would be a very neat and educational thing to do.  Get as clean and transparent an amp on the speakers they can manage and feed it with several different amps set to unity gain by the output loading.  Switch them in and out.  I like to know the results of doing that with some of the Hypex based amps.  Could be they are undetectable. 

[esldude]

1 minute ago, sandyk said:

 Dennis

 The attached is what I am referring to with the large increase in distortion just BEFORE it actually reaches clipping.

 

Alex

I wouldn't call 1% or less a large increase.  But I think we are thinking of the same thing having seen your latest post.  Yes, that is about where fogginess comes in.  Class A if much good does this smoothly enough on peaks it isn't going to stick out like a sore thumb and can enhance some aspects for some people's taste. 

[esldude]

2 minutes ago, sandyk said:

 Dennis

 With the amplifier that I showed, it is also possible by increasing the supply voltage rails and markedly improve the PSU current capabilities to do up to 30W in Class AB without the huge increase in distortion shown.

I owned a Pass Aleph 3 at one time.  30 watts class A, not capable of anything else.  Single ended FET. 

 

It could sound very, very good with a speaker it could handle.  It sounded like class B with most speakers most people might own.  Forget anything with ports including a little Radio Shack Linaeum LX5 speaker.  With Quads it was pretty good if you could contain yourself on the volume.  A good match with Quad 57s too.  Fantastic on K-horns or LaScalas.  Maggies were a bit too much drain on the limited current capability.  This same idea might be the best headphone amp one could imagine repackaged for that use.  Of course I've used a couple SET's on phones and find them good for that purpose.  But I don't like listening over phones. 

[esldude]

4 minutes ago, Ralf11 said:

 

Thanks!

 

Any thoughts on the PS Audio Class D gain cell (non-Class D initial or input stage) sound?

 

esp. if it get fed by a tubed pre-amp (ARC LS25 Mk II)....

Haven't heard the gain cell.

As I recall the ARC was pretty clean. With just a touch of lit up from within mid-range.

[esldude]

Looking at stereophile measures the Gain cell is the PSAudio input stage feeding an ice power amp. The only obvious differences are more noise than ice power amps usually have.

[esldude]

Was not thinking of warmness on the ARC. More a slight highlighted mid-range with good extended lows and full range treble.

[esldude]

The reviews I referred to were for the 700 and the integrated. 

 

https://www.stereophile.com/integratedamps/106ps/index.html

 

Despite McGowan claiming the gain cell is the perfect amplifying module with noise below -100db, we see a different story with measurements.  While other ICEpower units do get those low noise figures.  Gee where have we seen such dog and pony shows before? Oh its high end in the modern world......... par for the course. 

 

https://www.stereophile.com/content/ps-audio-stellar-m700-monoblock-power-amplifier-measurements

 

For the 700. 

 

Putative class A front end plus real noise. 

 

There are places to get ready to play Hypex. 

 

If you can wait a few weeks, you could look at March Audio's soon to be released NC400 amp.  I think it is NC400 based. 

 

https://www.marchaudio.net.au/

 

Here are some measurements of a DIY NC400 Hypex kit. 

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-hypex-nc400-diy-amp.5907/

 

 

 

[esldude]

14 minutes ago, Ralf11 said:

Thx - waiting is no problem; tho it looks like 2 of the N400s with case are only $750 (in Europe) and are trivial to assemble

Yes, I've not done it, but they do look like an afternoon of work and you will be done. 

[esldude]

5 minutes ago, sandyk said:

With exactly the same high amount of 460kHZ crap into the tweeters as Shadders has already pointed out elsewhere, despite using the AES-17 filter for measurement purposes. As  I pointed out elsewhere, this frequency is right in the middle of the Intermediate Frequency passband of Superheterodyne A.M. radios and has the potential to disrupt AM radio reception of weak AM  radio stations, even for your neighbours !

The gasoline in my car has the potential to disrupt the molecular structure of many things by blowing up and setting them on fire.  But the way it is used means its normally not a threat at all.   Most certainly I don't hear 460 khz.  

 

My microwave oven puts out 1200 watts in the same frequency used by my satellite TV dish.  Yet I can run the microwave and still watch TV which is using a super duper weak signal on the same frequency.  In fact the microwave output is about 120 billion times larger than my satellite signal which I can use just fine. 

[esldude]

Okay can we just drop the crap on AM radio being bothered by class D amps?  I've got a multiband radio I can tune you the class D frequencies. Right next to it you can pick up something. 10 ft (3.3 meters) away nothing.

Not a problem. Moved on.

[esldude]

33 minutes ago, sandyk said:

Of course you will claim this as you are a manufacturer of Class D amplifiers.

 I prefer to wait for the results of further testing by Shadders, who is quite knowledge in this area due to his technical background, and has already pointed out the high level of HF at around 460kHZ into the tweeters that manufacturers AND some reviewers love to cover up as being meaningless.

 

Next you will be claiming that 24/192 PCM is also pointless as there are no audible musical harmonics above 22kHZ ?

Think the very low level 460 khz signal could function like mechanical dither.  Preventing stiction and helping the tweeter move more freely.  

 

https://link.springer.com/article/10.1007/BF03185078

Completely meaningless mechanical dither citation involving lasers and gyroscopes.  Got to be cool if it has gyroscopes and lasers.

[esldude]

16 minutes ago, sandyk said:

 Perhaps I should hook both legs up to the output of a Class D amplifier and see if it helps with age related problems such as joint stiffness ?

I thought both of your legs whistled.  I believe you'll suffer from skin effect in any case.