Who tried Class D only to return to S/S or Tube

Your saying is that there will be no higher switching frequency developed in the near future, because there is no issue with at the moment, you need to re-think that one big time, seriously. 

Cheers George  

The switching frequency guidocorona, may be 520khz, but it’s the amplitude as well of it not just the frequency and has to be filtered at the end with all that rms power by low order filters that have to take that power. 

From what I’ve been told by those in the know of Class D technology this has to be shifted up 5 to 10 times higher so the filtering of it on the output of a Class D amp can then also be shifted up higher, and therefore not be affecting the audio band, with audio band HF phase shifts or audio band HF roll-offs.

On most of todays Class D amps that try to get the highest frequency response they can get, you may hear a sizzle from a high bandwidth tweeter if you put your ear to it, if it’s not muted eg: in-between tracks on a cd.

Then there are those Class D’s that want to get rid of that sizzle which filter it even more savagely, then those ones can be starting to roll off the audio HF already at 5khz.

The sounds of the two can be then different in the upper-mids and highs, one being hard or harsh because it lets through some of the switching noise. The other sounding opaque or soft in the upper mids and highs.

Therefore to cure one or the other the switching frequency needs to be much higher so the filtering has little or no effect within the audio band.

Analogy: is to remember the early days of cdp’s with their brick wall filters, which on paper looked ok but sounded shocking, just because they wanted to show a flat 20hz-20khz frequency response. But in Class D amps this filtering is low order and happens at the end of the power amp at full rms wattage power levels, and the filters need to take all that power handling.

Then there's the SMP power supplies another problem again, that some Class D manufactures try to get around by powering with more expensive to make Linear power supplies.  

Cheers George  

Can it be enhanced further?

Yes it can and soon I think, and I'll be there when it does, as soon as I see the technology about to become available from the big multinational component manufacturers, to supply the Class D manufacturers with. 

I'll get the jump and flick my expensive power hungry potential boat anchors before it's too late, and wait for the 2nd generation Class D to appear, even if it means I'm without music for a while.

Cheers George 

Once again I ask you the question, simple yes or no will suffice.

"Your saying is that there will be no higher switching frequency developed in the near future for Class D and what's now being used is enough"???

Cheers George

Well said Mapman, I myself am not ready yet as I outlined, but once the new (let's call it 2nd generation)  far higher switching technology happens, I'm jumping in with both feet, compared to my setup at the moment the bass/upper bass of todays good class D amps is already better.

I just have to time it right when I'm ready to make the jump as my two biamped power amps can re-coupe enough $'s s/h before they become boat anchors to get a pair of good 2nd generation class D's, and the same to a degree will happen to the 1st generation class D's as everyone will want to dump them also.

Cheers George    

guidocorona, if you were any linear amp designer and saw on the r&d bench test a square wave that looked like this.

http://www.stereophile.com/images/1212AM1fig02.jpg

You would say this amp is broken, do not put it into production yet till we get rid of that ringing.

This is what all Class D’s look like, and if they filter the s**t out of it so it doesn’t look half as bad, then you would have an amp that is rolled off at -3db at 5khz (no highs).

You been told now by a few, that the technology is not there yet to get that (ringing saw tooth) out of the audio band.

Once the technology is there and they put that switching frequency way up higher, then and only then will they be able to filter the s**t out of it away from the audio band and leave a nice clean square wave, and only then will Class D have become of age.

Cheers George   

I’m waiting for the Class D component technology to advance enough so the switching frequency can be much higher, only then will the switching frequency artifacts be abled to be filtered out away from the audio band.

As of now it’s too low and when filtered, effects the audio band HF with phase shifts and or roll off’s when filtered out.

But I believe it will come soon, then it will be only way to go, and linear amps may all become door stops or boat anchors.

Cheers George