Class D = Trash?

    George,

You stated:  "All your doing at the moment is trying to protecting your investment so it won’t take a monitory nose dive when this new technology becomes mainstream and finally puts Class-D into the hi-end Audio bracket, with today’s great linear amps
Keep that finger on the sell button and press it before they become obsolete."

     Protecting my investment?  I've never considered my amplifiers an investment since I began buying them a few dozen amps ago.  As I recall, the vast majority of "investments" I've made in my history of buying amps have been of the 'buy high and sell low' variety.  Hardly a recipe for success.

     Fortunately, every "investment" I've made in the many amp transactions in my lifetime were made with an expected ROI (return on investment) of improved sound quality in my system, not a financial one.

     Since I consider improved system sound quality as my ROI when buying an amp, my 3 "investments" of about $3,500 in class D amps have already been extraordinarily successful, with Sonic Gains already greatly exceeding my expectations. 
     The Sonic Gains continue to flow freely from these amazing, small, light, great sounding, neutral, low noise, powerful, highly dynamic, detailed  and affordable "investments".  Due to the very low levels of heat they produce, they'll likely continue to reliably provide their sonic dividends for many years to come. 
     Regardless of whether higher switching frequencies and faster/better FETs are able to even further improve class D amp performance,  my current class D mono-blocks are providing remarkable performance, with absolutely no detectable sonic artifacts/anomalies in the audible range, at switching frequencies in the mid 500kHz range. I, therefore, have no need to await affordable higher switching frequency class D amps to enjoy their promised benefit of not negatively affecting performance within the audible range since I've already been enjoying this for the last 3 years.
     While I already know and appreciate how spectacular class D sounds without the switching frequencies having affects within the audible range, out of curiosity I'll likely still audition a pair to hear how the faster/better FETs affect class D performance.

Later,
 Tim

Again can't see the forest through the trees.

Not one mention of the output filter that has to address the switching noise of the switching frequency, which is the Achilles Heel with present day switching frequencies.

Cheers George

" Not one mention of the output filter that has to address the switching noise of the switching frequency, which is the Achilles Heel with present day switching frequencies."
George,
     I understand the importance of having a good well matched passive filter in class D amps to remove the ultra high switching frequencies from the signal path after their Pulse Width Modulation job has been completed. I agree that this is a critical component in the process since this is where your theory states these switching frequencies can affect the audible range if not completely filtered out.

     Perhaps I just got lucky and only bought class D amps with exceptionally good passive filters. If they weren’t so good, maybe I could catch a trace of the switching frequencies affecting the audible range that you mention so often. Thank you, George, I think you just might have solved the mystery of the missing sonic artifacts/anomalies in my, and likely boatloads of others’, class D amps. No wonder nobody believes your theory; All the evidence is being filtered out effectively just as designed.

     Please tell me the class D amp brands and models of class D amps you were able to detect some audible artifacts from. We can compare all the specific filters operating flawlessly in our class D amps to the specific filters obviously working so poorly in the class D amps you listened to that inspired your infamous and discredited theory.

Thanks again for your help,
Tim

Yes, and they are the industries top designers, nothing will change until that dreaded switching frequency is taken up much higher. So then the output filter can do it’s job properly without any effects down into the audio band.

Technics is leading the way with the SE-R1 with twice as high switching frequency, but it’s not mainstream yet, and really should be even higher, one can only hope.

Cheers George

It’s not just the switching frequency, but a combination of that..and some other potent problems. Some things can be done to fix it and I have my ideas on how to tackle these critical ’other’ problems. The solutions are all valid on paper, but the real world may say different. I have successfully dealt with these problems in other arenas of design, so the knowledge should be transferable. We shall see. That, is, if I ever manage to get to the point where I can spend time fooling with these Class D problems again. Too busy cranking cables out the door right now.

I tried to do it on my own re existing modules (retrofit), but (un)said company wanted no part of it, unless it is in their domain - so I declined.

I have a pioneer sc68 which has class D amplifier. I have it hooked to KET 205/2. The sound is just beautiful. Just clean sound with details about all the different instruments in the music. Steve Wonder ribbon in the sky feels like he is singing in the living room :)
Also I am not sure what warm up period of 1000 hours mean.. It does not make any sense to me as I read these posts. The speakers need warm up period because they are mechanically moving parts that need to settle or get flexible.  If electronics change behavior that much with time.. that's scary to me from a Computer engineer perspective.