[justd]

Came across this article http://www.hometheater.com/content/anthem-statement-m1-amplifier . Basically they review a $3500 1000watt mono block class d amp, and come way less than impressed.

They say that class D amps are inherently not good at high frequencies. What do the forum members feel about this point of view. Has classdaudio done things differently.

My classDs sound pretty good to me at all frequencies. But i am not an audiophile. At least not as yet.

[john dozier]

Yes, ClassDaudio has done it differently. I have no problems with the highs in my very revealing system.. the devil is in the details. Regards

[DS-21]

Came across this article http://www.hometheater.com/content/anthem-statement-m1-amplifier . Basically they review a $3500 1000watt mono block class d amp, and come way less than impressed.

They say that class D amps are inherently not good at high frequencies. What do the forum members feel about this point of view. Has classdaudio done things differently.

That review was a train wreck. Just a bunch of idiot purple prose that demonstrated a total lack of understanding of the actual issues at play in Class D amplification by MF or his editors. (Or worse, a lack of interest in the actual issues at play.) For more on said issues, see my comment at the bottom of the review.

[john dozier]

Believe nothing Fremer has to say. The man is a complete idiot and an idealogue to boot. Typical of the "audiophile" press. Regards

[wushuliu]

Power supply capacitor upgrade: I'd like to try upgrading the capacitors in the power supply to the 10,000uF.  The Panasonic TSHA series were recommended earlier in this thread, but I can't find a TSHA-series in an 80v value.  What about the T-HA series, such as DigiKey part P10645-ND?

Even those are $12/each.  Six of those would run me $72.  Whereas I can get a whole new linear power supply using six 10k uF 80v caps for $54 from ConnexElectronic.

Any reason to do the capacitor mod myself versus just getting a whole new PS?

Depends if you believe PS caps can affect sound quality. I do and say if you are going to upgrade then spend a little extra and get Nichicon Fine Gold (avaliable from Mouser). Or go all in and get the Mundorfs from partsconnexion.

[wushuliu]

Came across this article http://www.hometheater.com/content/anthem-statement-m1-amplifier . Basically they review a $3500 1000watt mono block class d amp, and come way less than impressed.

They say that class D amps are inherently not good at high frequencies. What do the forum members feel about this point of view. Has classdaudio done things differently.

My classDs sound pretty good to me at all frequencies. But i am not an audiophile. At least not as yet.

Not all Class D are the same. Classdaudio amps never exhibited HF issues for me, but the chip it is built around is not being used in retail amps so there is no retail frame of reference.

Michael Fremer is a good reviewer. People who complain about audiophile reviews ought to try cranking out 2500 well written words every couple months based on a subjective experience. His life is audio and he has strong opinions, well good for him.

[john dozier]

Strong and not well based opinions. He is technically illiterate. Regards

[wushuliu]

Strong and not well based opinions. He is technically illiterate. Regards

Who reads Michael Fremer for technical expertise?

[Letitroll98]

I thought he made some rather good points about what to listen for when comparing Class D to Class A and A/B amps.  Whether you agree with his conclusions is irrelevant to the points he was making about listening for upper octave decay.  He said in his final point, "...listen very carefully, especially to the top octaves and the atmospheric cues on familiar music and movies. Pay particular attention beyond your immediate reaction to instrumental attack, and focus instead on the flow of the sustain and the quality and length of the decay."  This is exactly what detractors of Class D are noting, and is what bothers them about fully endorsing the technology.  He then says, "If you still love what you hear, don’t pay any attention to me", which is exactly what I would do, listen more critically to that area of reproduction.  If you've listened and are satisfied, enjoy the music. 

I've been searching for that description as I couldn't pin down what I was hearing while listening to the Ncores, a different amp than we're talking about here of course, but Class D nonetheless.  I loved the amps, but funds are being expended elsewhere so purchase was on delay.  But thinking back there was something in the high end that was different, not bad, different.  The amp was very balanced and I didn't find any obvious fault at the time, however I'd like to go back and listen anew after reading MF's commentary.     

[matt_garman]

Depends if you believe PS caps can affect sound quality. I do and say if you are going to upgrade then spend a little extra and get Nichicon Fine Gold (avaliable from Mouser). Or go all in and get the Mundorfs from partsconnexion.

My goals are (1) something to play with and (2) increased capacitance.  In other words, bigger capacitors, not necessarily better caps.  And whatever I do, I don't want to spend a lot of money (and in that regard, the Mundorfs are definitely out of the question!).  I wasn't able to find the Nichicon Fine Gold capacitors in 10k uF / 80v value on Mouser, unless I missed them.  Do you happen to have a link or part number?

[corndog71]

I really do love my SDS-258 and still think it's a bargain for what I paid.  However, in my opinion Fremer isn't wrong.  I've noted from the first day of listening to it how warm and easy to listen to the ClassDAudio amp was.  But I also noticed exactly what Fremer described was missing.  The highs are good but even compared to my modified Dynaco tube amp they're lacking in the highest frequencies, the decay, the room ambiance.  If you weren't familiar with seriously good gear out there you may not miss it.   I wasn't expecting the best for $600 but it works well enough as a back up for when my tube amps go down.  I actually fell asleep listening to it a few nights ago. 

[DS-21]

He said in his final point, "...listen very carefully, especially to the top octaves and the atmospheric cues on familiar music and movies. Pay particular attention beyond your immediate reaction to instrumental attack, and focus instead on the flow of the sustain and the quality and length of the decay."  This is exactly what detractors of Class D are noting, and is what bothers them about fully endorsing the technology.

That's just purple prose nonsense for "the output filter may interact with the load presented by the speaker in the treble."

It's not rocket science. It's just a gain block.

I've been searching for that description as I couldn't pin down what I was hearing while listening to the Ncores, a different amp than we're talking about here of course, but Class D nonetheless.

Equalize the frequency response, and class D doesn't have a "sound."

[john dozier]

+10

[wushuliu]

Oh, DS-21 is back. Well, that ends that.

[Barry_NJ]

Oh, DS-21 is back. Well, that ends that.

[video=youtube;1p6fTDGLHGQ]http://www.youtube.com/watch?v=1p6fTDGLHGQ[/video]

http://youtu.be/1p6fTDGLHGQ

[Letitroll98]

That's just purple prose nonsense for "the output filter may interact with the load presented by the speaker in the treble."

It's not rocket science. It's just a gain block.

Equalize the frequency response, and class D doesn't have a "sound."

Well of course. certainly.  I don't know why I didn't think of that myself.  It's so simple now, thanks for pointing that out.

And now for something completely different.   

[srb]

I see.  So the nuance of sound reproduction - the attack, the decay, the harmonics and their relative phase relationships - can all be made perfect by simple frequency equalization.  Brilliant!  The physical world is far simpler than I had previously thought!
 
Steve

[Letitroll98]

Also note that we may be somewhat unfair to DS-21 because of his, let's say, blunt presentation sometimes.  However you cannot deny that the output filter in Class D amps can affect high frequency response that can vary with different speaker loads.  Whether this can be solved by equalization is doubtful IMHO.  I think phase interleaving the transistors to raise the sampling frequency is a much more effective solution, which is what I believe is done with the Ncores and other Class D amps.  The data indicate flat frequency response into varied loads to above 20kHz, so it's not a frequency response problem that equalization can solve.   

[earplay]

Do tripath amps share the same "issue" in re high frequency as the class D amps?

[DS-21]

I see.  So the nuance of sound reproduction - the attack, the decay, the harmonics and their relative phase relationships - can all be made perfect by simple frequency equalization.  Brilliant!  The physical world is far simpler than I had previously thought!

In this case, yes. Point me to a bias-controlled subjective listening evaluation that demonstrates otherwise, and I'll change my mind. Point me to a sighted, un-level-matched listening evaluation, and who cares because such things tell us exactly nothing of any merit or relevance whatsoever in cases of subtle differences.

Also note that we may be somewhat unfair to DS-21 because of his, let's say, blunt presentation sometimes.  However you cannot deny that the output filter in Class D amps can affect high frequency response that can vary with different speaker loads.  Whether this can be solved by equalization is doubtful IMHO.

Why? Frequency response errors can be corrected.

I think phase interleaving the transistors to raise the sampling frequency is a much more effective solution, which is what I believe is done with the Ncores and other Class D amps.  The data indicate flat frequency response into varied loads to above 20kHz, so it's not a frequency response problem that equalization can solve.

Have you seen any data showing the performance of a Hypex amp into high frequencies with a dummy simulated speaker, such as the Ken Kantor-designed circuit Stereophile uses? While the test is probably too easy, it does do a great job of first-pass sorting amps capable of high-fidelity reproduction from colored-sounding crap. I've not seen such data for a Hypex, but I'd liketo.

Alternately, have you comparative measurements of a speaker driven by an Ncore compared to the same speaker driven by bog standard Class AB amp? If such data does not exist, if anyone wishes to send me an Ncore channel, I'll be happy to take comparative measurements between it and a standard Class AB boat anchor that was very positively reviewed by Dr. David A. Rich, and recently referred to by him as "still state of the art."

Do tripath amps share the same "issue" in re high frequency as the class D amps?

While I don't know why you put "issue" in quotes, my understanding is that Tripath amps have passive high-pass filters just before the binding posts, so yes those crossover components can interact with those in the loudspeakers, as well as the impedance of the tweeter.