Class D Technology

noble100
Georgelofi acknowledges the benefits of class D but mentions its low cost in a manner that suggests it’s not a further benefit,

Now that’s twisting words.
I suggested that future technology in higher switching frequency will be of great benefit to class-d, so then the output filter can do it’s job properly without effecting the audio band.

We’re trying to band fix the switching noise problems with some innovative (ML below) (Belcanto my last post) but not completely successful filter ideas.

Just look for one at the $50k Mark Levinson No53 Class-d monos. 4 x massive inductors for the output filter probably cascaded to get rid of the switching noise. Speaker designers know that doing this with filters has it’s own set of interaction problems. Didn’t get a great Stereophile review/measured performace.

http://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier#kXGk3Vi1RAApjFoi.97

Like I said before, I’ll be the first to get a Class-D once the switching frequency is around 3-5mHz so the filter can do it’s job properly, but at the moment nothing save for the very exclusive $30k Technics SE-R1 with a higher (double) but not high enough switching frequency, then my linear amps will become boat anchors.

Cheers George

Hi George,

     I didn't intend to twist your words, sorry.

     I reread your posts and I get that you are waiting for the switching frequency to be significantly raised before you'd be willing to 'switch' to one.

   I understand the theory that the current class D switching frequency is too low and affects the sound in the audible range but I can honestly say I don't hear any irregularities when listening intently to my system.  You may be completely correct but I'm just having a hard time faulting what I hear.  When I listen explicitly for switching frequency issues I mainly concentrate on the highest frequencies to make sure they are well extended and to make sure that spatial cues are present and the sound stage is well defined and stable both laterally and front to back.  

     Am I listening for the wrong things?

     Is there a simpler method to determine if the  switching frequency is too low and is  affecting anything in the audible band?

   I'm not really disputing the theory that a higher switching frequency  would upgrade class D amp performance.  I was just hoping to gain a better understanding of exactly how.

 Any assistance is greatly appreciated,
     Tim

























i honestly I  

I’m pretty sure that even if switching frequency becomes 1000 times higher than current standard and 1/10000000000 THD, Class-D will not convince many of audiophiles. For a lot of audiophile, ultimate transparency / cleaness / hifi is no more their goal these days.

Tim,

If you can't hear the difference, stop! :) Unless you are a QA professional, learning to tell the difference in equipment you couldn't hear before doesn't lead to better enjoyment.

I traded in my class A/AB amps after evaluating class D and finding them inaudibly different. I could not tell blindfolded which I was listening to.  I DO see potential for tweeters with rising impedances or high capacitances being too much of a challenge but that's not how I make my speakers. :)

Best,

Erik

ultimate transparency / cleaness / hifi is no more their goal these days

Those never were my goals.  Although resolution and a quiet background (similar to what you may mean by transparency/cleaness) are expected attributes in higher end gear, excellent tone, dimensionality and dynamics are more important to my enjoyment and, in my experience, it can be hard to find all three in a component.