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Class D Technology

So I get the obvious strengths of Class D. Efficiency, power output & running cool which allows for small form factors. I also understand the weaknesses somewhat. 1. Non-linear & lots of distortion that needs to be cleaned up with an output filter. 
So my question is, if it weren't for efficiency & power, would there be any reason to own a Class D amp? Do they beat Class A in any other categories that count for sound quality?  
seanheis1
kijanki's avatar
kijanki
4,430 posts
 
The main reason manufacturers of high end audio (like Rowland) use SMPS is low noise and line/load regulation.  You can find it in FAQs on his (or Benchmark) website. He uses SMPS  in preamps where size or efficiency play no role.

Yes, top manufacturers still use linear power supplies, but main reason is demand from people who, mistakenly, believe that if it has to be heavy to be good.
georgehifi's avatar
georgehifi
10,312 posts
 
Yes, top manufacturers still use linear power supplies, but main reason is demand from people who, mistakenly, believe that if it has to be heavy to be good.

Sez who???

Cheers George
kijanki's avatar
kijanki
4,430 posts
 
Well, most of people on this forum (including you) think that SMPS is noisy and linear power supply is better.  This believe comes from bad rap of noisy crude computer SMPS applications.  They don't even realize that "Linear" power supply is a primitive unregulated switcher.  I addition, many believe that when something is smaller and more efficient something else has to give (that's human nature).  They apply this believe to both SMPS and class D amplifiers (that are basically controlled SMPS).  In view of that amplifier manufacturers would be stupid not to keep using "Linear" power supplies.  Only few true pioneers like Jeff Rowland had courage to develop state of the art SMPS supplies that are extremely quiet  (noise very easy to filter out at 1MHz operation).  Even 50kHz SMPS executed well are far better than "Linear" supplies IMHO.
mapman's avatar
mapman
22,342 posts
 
So much noise about nothing of real consequence.

I will of course look forward to improvements in switching frequency under the assumption that things will get even better overall down the road at least on paper. How much difference it makes practically is TBD.

George I do think you are too obsessed with this one technical issue. You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone. To hell with all the rest that goes into these things if that is all the story. 
georgehifi's avatar
georgehifi
10,312 posts
 
You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone.
I have, done numerous bench/listening tests, and tried to come up with my own cascaded output filters like Belcanto I believe did with their 600ref monos, but doing filters this way has a other set of problems (interactive ringing) if your familiar trying cascaded filters for speaker xovers.
Mark Levinson with their no53 also tried it but that fell a bit foul with a Stereophile review/measurements.

Cheers George
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