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Class D is just Dandy!

I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.

That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.

For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.

Please share your experiences with class D amps!
erik_squires
georgehifi's avatar
georgehifi
10,312 posts
 
shadorne6,590 posts01-28-2018 8:06amLittle known factoid.

AES17 brick wall filters allow Class D Amps to report specifications IGNORING all the switching noise above 20KHz!!!! And there is a LOT of noise....

Stereophile do similar now testing Class-D as not to upset readers with the noise on the graphs and to keep the manufacturers happy in case they may advertise. 

They use a very low power handling Audio Precision's auxiliary AUX-0025 passive low-pass filter between the Class-D's speaker output and the test equipment, which eliminates noise above 200kHz.

On figure 3 you can see the switching noise of the 1khz test sine wave, it will be far greater if they showed with a 10khz sine wave.

https://www.stereophile.com/images/218PSM700fig03.jpg
Fig.3 PS Audio Stellar M700, small-signal 1kHz waveform into 8 ohms without AP AUX-0025 low-pass filter.

If this noise was on test waves of the audio band like this on a linear amplifier, any tech would say it's faulty.


Cheers George   
erik_squires OP
16,386 posts
 
I must say that for any amplifier, the PS Audio Stellar's measure poorly.

Most Class D amps I know of do considerably better. I'm more than a little surprised PS Audio put that out there.
erik_squires OP
16,386 posts
 
Compare the PS Audio design to the Bel Canto monoblocks:

https://www.stereophile.com/content/bel-canto-eone-ref600m-power-amplifier-measurements

Far lower noise and distortion.


georgehifi's avatar
georgehifi
10,312 posts
 
Most Class D amps I know of do considerably better. I'm more than a little surprised PS Audio put that out there.


Please show just one Class-D, with a clean 1khz sine wave, without using the Audio Precision's auxiliary AUX-0025 passive low-pass low power filter.

Cheers George  
arcticdeth's avatar
arcticdeth
1,572 posts
 
Heard it again, still don’t like it. Wyrd4sound and..
Veritas amps, looked cool, sound was blah to me. 
I like class a, or ab, even a switching class h has more feeling to the music.  Something about the d sound just don’t sit right with me. 

 It’s just.........like 1 dimensional, or no emotion to the music, a,ab,h just have a quality to them when I’m listening, I don’t get from d class sound. 

H class I’m referring to is my Carver sunfire. 
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