Class D Technology

D = duck.

The output filter vs switching noises frequency is the bottleneck for Class-D HF distortion and low impedance drivability.

As I said when in the future when it is not a bottle neck, and the switching frequency is much higher, I too will dump the hot inefficient boat anchors and go Class-D.
But today it doesn't compete with good linear s/s or even tube (especially OTL tube) which has other limitations.

Cheers George 

George im guessing you should be looking at specs and data of the Rowland amp not the ice module it uses alone. I’m pretty sure Rowland like others do things like beefed up power supply to achieve performance. Again I think you are selectively choosing your facts and data to support your case. Are you a lawyer? Many of these amps get rave reviews and are happily owned by many. Your technical case for why these must sound bad does not add up. Plus I can assure you the newer good ones done right are right up there. It’s ok if not your cup of tea for whatever reason. But that’s about it. If I had listened to the skeptics a few years back rather than drawing my own conclusions to take he chance I’d have maybe missed out on years of enjoyable music by now.   

Georgelofi - you are talking about harmonic distortion below 0.1%, that are inaudible (unless you're a bat, of course).  I've noticed that you also tried to apply psuedo-science to sigma-delta converters.  I am afraid one day you'll find that SACD is the same.

There are many class A or AB amps that have similar bandwidth but nobody talks about phase shifts.

That’s because good ones are usually much faster, and they don’t freak out at low impedances like ClassD does in distortion and loading.

I like to see bench tests v reviewers subjective listening. As Stereophile does.

But here is what a reviewer from another mag said subjectively, without any bench test to back his listening.

" Here is what the amp doesn’t do. It isn’t airy and it isn’t laid back."

Good highs are airy, they float with harmonic structure.
Cheers George

The JR 102 uses the Ice 200asc modules as you are probably aware.

Look at the distortion figures for the highest their willing to put up in red which is just at 6.5khz. Look how fast the distortion rise is for the given wattage. And this is all at just 4ohms, I would love to see it at 2ohms.
If you can then visualize just what the 15khz one looks like, if they rise this rapidly from 100hz to 1khz to 6.5khz you have an idea of what’s going on the upper mids and highs.

Then you can imagine what happens if the’re driving an ESL speakers which can go to down 1ohm.
This is just one I found I'm sure there's more if I dig.
http://www.icepower.dk/images/200asc_700px.jpg

Cheers George

Rowland model 102.  There are many class A or AB amps that have similar bandwidth but nobody talks about phase shifts.

My class D amp has 60kHz -3dB bandwidth. Georgelofi - you must be a bat?

What brand model? Maybe I can find some non affiliated bench tests

Even so with those figures do some homework at -3db at 60khz you will have phase shifts all the way down to 5khz,  because of the low order of the switching noise output filter.

Cheers George

Mapman, I am using Spec RSA717ex, it has class of its own ,Spec is better sounding than the  Class AB Luxman-505ux I have used previously, praised in various reviews, luxman sounded cold  and suppressed to me.
And all my inputs given in my previous posts are after comparing Spec with Audio Note Oto phono SE, only 10watts....

57

I recall when I was in college I could hear well to 20khz. I know because I ran tests.

I also found it much harder to get sound that was not fatiguing. This is back in analog days even. 

These days I know I cannot hear to that extent which is normal for ears my age. I find listening not fatiguing at all and can listen enthralled for hours and not want to stop. With most any kind of music or recording. Well except the occasional really bad modern loud pop mp3. That’s what its all about. Maybe there is some advantage to getting older after all.

Mapman, with all due respect, how old are you? 

Murgesh what clas d setups have you heard? Why assume that what you heard is indicative of all cases? That’s called jumping to conclusions. My experience is the exact opposite of yours.


The c5i is in fact a digital Class D integrated amp ( not just class d). and the sound is nothing like you describe.

Sean

You are so screwed if you buy into class D. 

As Donald Trump would say: trust me on this. 

Mapman +1.

Georgelofi - if you don’t like the sound of particular amp or even class of them just say it, but making up pseudo-scientific reasons is just plain silly.

There is absolutely no fatigue with the C5i driving any of my speakers including some that are documented to potentially lean that way with the wrong amp. 

Technical difference aside(which I am not an expert), purely based on the sound, tubes has significantly more naturalness and fatigue-less, yes I understand that every  own has  own preference, but end of the day we are thriving for the sound what we like, which give us endless pleasure and to me Class-D still lacks the connection to the mind which interprets as its as more of digital sound...
Yes, Class-D had the advantage of running cool, clean sound, lower utility bill....it matters with every own of us what we prefer the beautiful analogue  sound or the convenience of the Class-D technology??

George you conveniently forgot to mention some think the sound including the high frequencies are quite good and not flawed.  

Lets not selectively filter feedback just to help make a case.   

Im listening to my Bel Canto C5i Class D integrated with Triangle Titus speakers currently.  Other than the clean articulate bass I could easily think the amp was a very resolving and clean and dead quiet tube amp.  The treble is as good or better than most anything I have heard.  The sound draws you right in. 

So so let's stop trying to convince people the technology is flawed or does not sound good.   It's as good as anything these days done well.   Done well is the key like with any technology old or new.  

If bought down low to erase most of the switching noise, this intrudes into the upper frequencies of the audio band. Which makes it very smooth but robs most of the harmonic structure of the mids and highs, this "could" be compared to tube or class A s/s smoothness.

My class D amp has 60kHz -3dB bandwidth. Georgelofi - you must be a bat?

No I’ve never heard one. How does Class "D" compare to SS? I’m a tube guy who has not heard the very best SS amps

We, most are all in agreement that Class D is great in the bass. To me where they differ mainly is in the upper mids and highs, some saying there’s hardness up there, and others saying there’s missing information that causes larger then usual gaps between notes creating the "illusion" of a blacker background. I call it an opaqueness.

The different sound of Class-D especially in the upper mids/highs, comes down to how close to the audio band the mandatory output filter on all Class-D’s is bought down to get rid of the class d’s massive amount of VHF switching noise.

If bought down low to erase most of the switching noise, this intrudes into the upper frequencies of the audio band. Which makes it very smooth but robs most of the harmonic structure of the mids and highs, this "could" be compared to tube or class A s/s smoothness.

If it’s not bought down to low it lets quite a bit of VHF switching noise through, this maintains the harmonic structure of the mids and highs but also adds a certain hardness to the sound of class-D

To me the only way to cure this comes in future semiconductor component development, which will allow the switch frequency to be set 5 x higher, so the the output filter can be set much higher as well so then do it’s job properly to get rid of all the switching noise without effecting any of the audio band at all. Then they’ll also be able to drive full current even down to 1ohm from 20hz to 20khz, instead of today falling off a cliff below 4ohms.

Technics have a >$30k amp the they developed with their own components to get the switch noise up 2 x as high as anyone one else, a step in the right direction, but it needs to be higher again 5 x the norm today. They still do not include a 2ohm wattage figure in their specs, as it would still show limitations.
http://www.technics.com/us/products/r1/se-r1.html
When that day comes we’ll all be using them and our heavy, hungry, hot tubes and SS, will become boat anchors.


Cheers George

The new Wyred  SX 1000R mono's sound great. They replaced the great Vitus RI 100, 13k retail. 6moons review pretty much on. Nothing beats big power if it is decent.

I'm very curious about Class "D" amps. No I've never heard one. How does Class "D" compare to SS? I'm a tube guy who has not heard the very best SS amps, but I did hear an ARC SS that I didn't like.

If a person prefers SS to tubes in general, his opinion is less valid to me, than someone who prefers Class "D" over tubes or claims that he can't tell the difference.

I've been told that for watts of power, class "D" is cheaper; that's nice, but I don't have a serious power problem, just curious.

My tubes have a black background; I know this is not supposed to be so, but current tube equipment has achieved that. Maybe not as Black as Class "D", and yes, there are levels of Blackness.

While the quickest way to find the answer to these questions is to buy one; that is not an option. I hope I've arranged my questions in an order that won't offend anyone, but will get an answer to the best of their ability in regard to Class "D"

Just because you heard a class D amp sound better than a tube amp in a particular situation does not mean that all class D amps sound better than all tube amps, or even that the particular class D amp sounds better than all tube amps. It just means that in that situation you heard something better that you liked between the two involved.

Who said that? That statement is completely erroneous

Who said? you know exactly who, since you copied.   This statement, made by Atmasphere,  is absolutely true stating that you can like any class of an amp more than another.  Nothing erroneous about that.

This statement is false. 

It is not false at all! 

"It used to be a sign of superior good taste to diss class D. Today it's become a surefire tell of sad ignorance."

Anyone who degrades class D as a whole is clearly ignorant about the technology or has comercial interests against it. As with any other topology, making a generalization about sound performance is an error.

Just because you heard a class D amp sound better than a tube amp in a particular situation does not mean that all class D amps sound better than all tube amps, or even that the particular class D amp sounds better than all tube amps. It just means that in that situation you heard something better that you liked between the two involved. 

Who said that? That statement is completely erroneous, in fact is the complete oposite of what I clearly stated above:

I said: "I have experience with many amplifying topologies (meaning class A, A/B, D, H), and I have found good and bad examples in each".

Who makes the latest generation of Class-D? The best class-d I heard, Hypex has been on the market for a long time. I wonder how good the latest generation class-D is compared to Hypex.

Hypex latest generation is Ncore which has several years in the market. Anaview and Pascal also have very good designs, that when correctly implemented provide similar or in some cases even better performance than Ncore.

And as I said, not everything is the class D module in the design. The input buffer, for example, is a critical part that can completely alter the character of the amplifier. There's been greater progress in this matter, than in the output modules themselves.

So its pretty much on par with everything else audio these days. Some like it and some not so much.

its nice to have choices.

The difference is Class D will only continue to get even better.

Someday soon everyone may agree.

Mapman - I would say Class D is similar to tubes as far as opinion goes. People either like the sound or they don't. I am not saying that tubes sound like Class D (far from it), just that they are both controversial. Very rarely will you hear someone say something bad about Class A solid state relating to sound quality/accuracy.  

So if its not obvious by now the question has been answered repeatedly in some cases.

Some like it already and some not so much.

I’m on the like it side with Kijanki.

So its pretty much on par with everything else audio these days. Some like it and some not so much.

its nice to have choices.

The difference is Class D will only continue to get even better.

Someday soon everyone may agree.

Or not.....

Cheers!

I will state just the opposite.  Violin sounds like violin without scratchy glazed harmonics of class AB amp.  Same goes for the cymbals that sound brassy and meaty instead of bright and splashy.  Cello sounds deep and resonant.  Transients are incredible while amps keep composure under heavy current demands (orchestra forte), most likely due to regulated power supply.  The other thing I noticed is low level performance.  When I listen soft at night - highs and lows are still there.  Imaging is even better, but it might be due to reduced reflections.

Somebody described sound of Hypex as a sound of very good class AB amp while  Icepower was described as more of a tube amp sound (half bridge vs full bridge output).  Icepower is very good in spite of some negative opinions here.  Now we have more choices, Pascal being one of them.  

Speed of Mosfets improves every single year, but now new switching devices are coming - like Enhanced Mode Gallium Nitride Fets (eGaN Fet) that switches many times faster without overshoot or ringing due to ultra low capacitance and inductance.  The best days of class D are ahead of us, but I enjoy it immensely already.  

The black background many listeners can hear with Class D indeed suggests the heavy filtering is in some way affecting the audible sound.

Myself I would not describe it as a "black background".
But rather a "harmonic black hole".

Cheers George

Sebollo 001,

Who makes the latest generation of Class-D? The best class-d I heard, Hypex has been on the market for a long time. I wonder how good the latest generation class-D is compared to Hypex.

Today it's become a surefire tell of sad ignorance.

This statement is false.

Just because you heard a class D amp sound better than a tube amp in a particular situation does not mean that all class D amps sound better than all tube amps, or even that the particular class D amp sounds better than all tube amps. It just means that in that situation you heard something better that you liked between the two involved.

Heck, even in our lineup we've managed to make improvements in the last several years. I encounter people that think that just because they heard our amps 12 years ago on a certain speaker that they have a complete understanding of how our amps perform today on different speakers (or even the same speaker they heard 12 years ago....). They don't.

It just doesn't work that way!!! I regard this comment (taken out of context of course so simply as quoted) as being outrageously inaccurate.

I have experience with many amplifying topologies, and I have found good and bad examples in each. Class D just happens to be one of the newest, with many improvements in the last generations.

100% agree with the following quote from an experienced reviewer:

  "Today experienced analog circuit designers have learnt how to harness switching tech (class D) in ways that please even those who initially wrote it all off as unfit for serious purposes should one be trained by class A amps of the transistor or tube variety. It used to be a sign of superior good taste to diss class D. Today it's become a surefire tell of sad ignorance. "

Class A particularly when no NFB used tends to have a somewhat warmer sound.

I have not heard Class D that I would call an inherent warm  sound, in fact not warm at all, however if a touch of warmth  is what one seeks a tube pre-amp upstream can help accomplish the goal.   The ARC sp16 I use with BC ref1000m amps does this to perfection through my very neutral sounding OHM Walsh speakers.   Tweaking of ICs and such can even make a useful difference here.

Hifi is like making soup.   You gotta toss all the right ingredients in the pot together to make it tasty for you.    Class D is a very good base to make your soup with IMHO.    Where it goes from there YMMV.

Great discussion and lots of valid points. I agree with those who feel Class D is not ready for prime time - great for PA and subwoofers but perhaps a few more years are needed for them to become viable to the majority of critical audiophile listeners. The black background many listeners can hear with Class D indeed suggests the heavy filtering is in some way affecting the audible sound. 

I own Class-D from Spec corporation, it sounds clean, plenty power for 50 watts, taut bass, smooth high, compact size........, however I just  don't get connected to the music as opposed to 'tubes' amps
The magical sound is only from 'tubes' ... that for my ears

I think I can tell if the amp I’m hearing is Class-D or Class A.

In my experience, Class-D always makes me think, "hmm, nothing wrong. great sound!", and a good Class A makes me think "how you can do this? what’s going on here!". Cheap class AB’s has a typical glassy haze, but I have never heard the same thing with cheap Class-D.

Somehow people cannot comprehend that class D amp is purely analog and switching itself is inaudible. Switching is present all the time - even without input signal. Place ear against the tweeter and you will hear very low typical amp’s hiss - likely much less than with any class AB amp.

That wasn’t my experience between a Spectron Musician III mk2 (Class D) versus a Sanders Magtech (Class AB). Although the Spectron is quiet, it’s not as quiet as the Magtech. Both are inaudible at the listening position though.

@mr_m I bought mine with upgraded tubes and had a bunch of upgraded power cords around. You are right. Amazing.

nferre66. Try some vintage NOS Mullard  12au7 tubes in the preamp stage of the Pharaoh. Also a quality inexpensive power cord such as the Harmonic Technologies AC-11. You will be amazed....

Last night I listened very closely to my Class D Lyngdorf Int amp comparing it to my highly modified (for the good!) Cary Rocket88R amp with very expensive a great sounding NOS tubes all around. I must say the Lyngorf has soul, body, texture and tone in spades. 

I do do keep mine on 24/7.  

Composed is a great adjective that describes what I hear quite well.  

To me, not being much of a technical whiz about these things, it's all about the ears. We all have different tastes and we all have different ears, thus we all have different preferences. I recently bought an ARC DSi200 here on Audiogon (the prices for used ones are very attractive) as an expedient replacement for my very capable Hegel H-200 integrated. The latter likes to be powered on 24/7 and uses up 60 watts at idle. Since I live in an area (Northern California) where electricity rates are abusive, I wanted something more efficient than the class AB Hegel to power my Proac Response D2s. I have to say that I'm very happy indeed with the ARC. It has no trace of the harshness or thinness, or even soullessness people so often ascribe to class D amplification. Music sounds very controlled and (pardon the pun) composed which suits my tastes admirably. I'm very happy with what this sound and hopefully, when the next utility bill arrives, I'll be happier still. 

Thanks for the posts @mr_m and @mapman 

At least I know I'm not nuts. Three friends have come over and their reactions are all the same- once they pick their jaws up off the floor, they all want a Pharoah. One has already ordered his and is awaiting delivery.

I have a Rogue Pharaoh. It sonically destroyed  a Macintosh C-45 pre and MC-402 power, SS. 11k worth of Mac gear. In listening comparisons, I thought the Rogue went toe-to-toe with ARC integrated.

I've heard the Pharoah Maggie pairing and thought it to be quite a good one.  I could live with Rogue Pharoah very happily.   Great product and good value.   

I purchased a pair of Maggies earlier this year, and a pair of Emotiva XPA-1 monoblocks to drive them. While the performance was good, I had a feeling I could do better.

Posts like some of the above kept me from trying Class D. Magnepan themselves caution against it.

On a whim, I bought a Rogue Audio Pharaoh integrated that I saw posted here. I've not heard a Rogue I didn't like and didn't see them putting out something below their standards. I couldn't be happier and my system now uses 75% less power. The Pharoah drives the 1.7i wonderfully. 

If you are listening to Diana Krall, and you hear Katy Perry, the problem is much larger than amplifier technology.   You either have one heck of a malfunctioning system, a set of speakers that were dropped out of a truck before being delivered to you, or you are experiencing neurological problems that require immediate medical attention. I'm not being facetious...Katy Perry and Diana Krall sound nothing alike, aside from both being female. If that's genuinely what your ears heard, you have bigger issues than deciding what amp to buy.

bcgator, it was an analogy. Diana Krall has a warm voice and the Ice Module made her voice sound cold and thin. Katy Perry has a cold and thin voice...hope that clears things up. ;-) 

seanheis1 OP

It seems like some companies are aware of this and add tube input stages to try and add harmonics and meat back to the bone.  

Yep, agreed Sean, that's called microphonics, colorations, distortions or euphonics, and not the real harmonics of the instruments or voice that are supposed to be there, but hey some people like it, each to their own.

Cheers George 

If you are listening to Diana Krall, and you hear Katy Perry, the problem is much larger than amplifier technology.   You either have one heck of a malfunctioning system, a set of speakers that were dropped out of a truck before being delivered to you, or you are experiencing neurological problems that require immediate medical attention.  I'm not being facetious...Katy Perry and Diana Krall sound nothing alike, aside from both being female.  If that's genuinely what your ears heard, you have bigger issues than deciding what amp to buy.

I do not hear that at all.

Be careful about taking a small sample and drawing conclusions from that on the whole. I’d have to hear the same setup others have heard this with, Only then could I comment on the sound resulting from that particular setup and compare to others.