Class D Technology

Lots of great responses. When switching frequencies are 5x higher than today's, what will be improved? Will that prevent the saw tooth waveform challenge? Or prevent the need for a low pass output filter?

What makes today's class D amps sound cold and dry? I have experienced this firsthand with an ICE Module that I once owned.

Mapman alluded to a totally black noise floor. I also experienced this with the ICE module. So far, this is the only benefit other than efficiency & power output that has been discussed and can be attributed directly to the Class D topology. Or maybe this noise floor issue is unnatural and sounds are being cut off prematurely by not allowing for decay?   

CD's have become listenable....maybe some day so will Class D's

" What makes today’s class D amps sound cold and dry?"


I’d attribute it to the high damping factor in combo with the aforementioned transient capabilities.

Mine definitely sound best with speakers that like high damping. Usually larger ones with larger drivers that are inherently harder to control.

They are more towards the cold and dry on my little Triangle Titus monitors.

Not so on my somewhat larger and more extended Dynaudio Contour monitors or any of my other much larger and more extended speakers.

They are the cats meow on my largest the big OHM F5 series 3 floorstanders with much larger Walsh style driver often cited as benefiting from monster amps with high damping. That is very true!

The switching time is an issue. The output devices have to switch on and off at a pretty high speed. The problem is, they can't both be conducting at the same time. That is to say, it takes a certain amount of time for the devices to turn on and to turn off. If one is not quite off while the other is turning on, you get something called 'shoot though current' as the devices are essentially a short across the power supply without doing anything to drive the speaker. Shoot through current causes the output devices to heat up quite a lot. So it has to be avoided!

To solve this, there is something called 'dead time'. Its a circuit that makes the output devices wait just a little so that one is completely off before the other starts conducting.

The longer the dead time the higher the distortion. So if you can switch faster dead time is reduced and so is distortion. Right now the technology is to the point where the amps have become practical for mid fi, but they still have a ways to go before they can challenge a good class A transistor amp or a good tube amp. There is no question that this is a technology to be watched.

" Right now the technology is to the point where the amps have become practical for mid fi, but they still have a ways to go before they can challenge a good class A transistor amp or a good tube amp."

Mid-fi?  That's actually a funny statement!

As for challenging others, people need to listen and decide.   All amps have technical issues and challenges.  Citing these and comparing does not tell you anything about which sounds best.