Class D Technology

Al, thanks for that.

I was aware of the phase shift concerns and recall looking at measurements and reviews prior to buying to get a feel for what is going on.   Knowing no gear measures perfectly in all regards I decided to give it a try and was glad I did. 

I have to say to whatever extent my amps and gear may be imperfect or not, listening enjoyment is not affected.  I can listen for hours and never grow fatigued or tired.   That's not something I could lay claim to with my system prior to Class D. 

So as we know  in the end it always comes down to what one hears and can enjoy or not.    Measurements help scope out the likely candidates in advance, and their technical strengths and weaknesses but never tell the whole story regarding how things actually sound.

So while nobody including me has argued that more bandwidth done right is always a good thing, I do still think its unfair to dismiss Class D technology and products as a whole these days based solely on that.   The benefits will far outweigh the disadvantages for many  but probably not so much for those who are put off for whatever reason.

Shibui,
Thanks for your real world experience driven insight. I will always place more weight on actual use and listening experiences than the hypothetical/theory argument. Ironic given the contrary opinion of some on this threat that tube and class D amplifiers are superb driving your 1 ohm load Apogee speakers.
Charles

My good buddy Glen (shibui). A fantastic friend, an all-around great guy, and an ardent and experienced audiophile/music lover with a superb-sounding system. What more could anyone ask?

Phase shift and wrong summing of harmonics argument might look plausible (I claimed it myself) if not for the fact that my speakers already limit bandwidth to 22kHz creating larger phase shifts in comparison to 65kHz amp's bandwidth.  This 65kHz amp's bandwidth is responsible for about 20deg phase delay at 20kHz (that I cannot hear) and about 10deg delay at 10kHz (that I can hear).  One can argue that this phase delay might be beneficial since many speakers have positive phase shift at these frequencies.  I don't have data for my speakers, but I picked one of the speakers reviewed by Stereophile.  As you can see on the phase diagram (dotted line) speaker actually accelerates phase at the highest frequencies.  Phase delay caused by the bandwidth limit of my amp would improve summing of harmonics (Al, am I missing something?).  
http://www.stereophile.com/content/monitor-audio-platinum-pl300-ii-loudspeaker-measurements#Oze7AYHq...

There are many class A or AB amps that have bandwidth much lower than 200kHz (including Krells that have -3dB at about 100kHz) but nobody makes claims about  bad sounding highs.  It is a little of negative placebo effect - if you really believe that class D cannot sound good it will not.  

As for the hefty H2O power supply - it is unregulated and as such requires huge bank of capacitors to keep voltage steady and to filter out 120Hz ripple.  Jeff Rowland uses only very quiet SMPS, line and load regulated that operate at 1MHz switching frequency that is very easy to filter out.  In fact, he uses SMPS in preamps (Capri), where efficiency is not important, to lower the noise.  SMPS got bad rap from crude computer applications.  Either way works but traditional "linear" supply generates a lot of switching noise.  Also low inductance capacitors (like slit foil) are very expensive.  Why only a few companies use SMPS?  Perhaps because it is not easy to design good switcher and also because of market demand.  Many people believe that it has to be very heavy to work right.  Tiny ferrite transformers can carry at high frequencies as much power as huge transformers operating at 60Hz - not to mention wide supply voltage range and DC operation.  SMPS in mapman's amp can deliver 36 amperes for a full second!

BTW has anyone ever noticed a reviewer complain about phase shift when reviewing gear at a show? They can find all kinds of faults but seldom if ever that. Are they not listening right or is it just not there? Gotta wonder.....

It is a little of negative placebo effect - if you really believe that class D cannot sound good it will not.

I suspect some truth there as well. I went in not totally sure but willing to believe anything. I think.

SMPS in mapman's amp can deliver 36 amperes for a full second!

And....loving it!