Class D

Sorry, again, your show how ridiculous your statements are.

The amount of power the filter has to contend with in Class-D amps compared to a dac, now your showing how ridiculous your statements are.

This statement is wildly incorrect!


Although digital and class D amps both employ switching, it is important to understand that one is digital and the other analog. However the primary difference between the two is the the order of ones and zeros has significance with digital as does the word length. With class D it does not (there is no word length for starters....) and it is always switching states at its switching frequency. In a class D amp its the width of the on and off states that has significance, as these widths describe the audio signal.

As a result the filters are vastly different. The filter in a digital system is usually operating at a *much* lower frequency than a class D amp. So this isn't just about power!!

This statement is wildly incorrect! So this isn’t just about power!!

It’s more about power, because you can’t see the forest for the trees, with what Mark Levinson tried to do by series up "low order" output filters (so they don’t burn out) and trying to get a steeper roll off as not to introduce phase shift into the audio band in the upper mid/highs, which they achieved, but it had then other problems. https://www.stereophile.com/images/1212ML53fig02.jpg
Instead the simpler fix of of doing what Technics SE-R1 did and just raise the switching frequency to 1.5mhz.

It’s more about power, because you can’t see the forest for the trees, with what Mark Levinson tried to do by series up "low order" output filters (so they don’t burn out) and trying to get a steeper roll off as not to introduce phase shift into the audio band in the upper mid/highs, which they achieved, but it had then other problems

This comment really says you don't understand what's going on here. ML didn't do what you're describing. Its obvious from the internal photos that the circuit employs what is known as an 'H' bridge output (which tends to be common in higher powered class D amps). Its also common to see two chokes as a result- one for each half of the bridge circuit. Without knowing further details of the circuit its unwise to speculate further, but the fact of the amp being an H bridge is easy to see if you know what to look for.


The waveform at the link is a 10KHz squarewave. There is a small amount of overshoot, and what looks like a bit of an oscillation on top of the waveform as it is consistent with each iteration so does not appear to be a measurement error. As square waves go, that's not a bad looking one- most power amps will round the leading edge (if open loop/zero feedback you need 100KHz bandwidth to make that leading edge look right).


So I don't see the 'other problems' to which you referred by including that link. I might add though that more modern class D amps do make a better showing of this sort of thing. When you attack a technology based on older examples, it really doesn't help your argument!

Must be soon, you really have gone into full product protection mode, and there’s no stopping you.
Good luck is all I can say, for your new Class-D venture.

And Class-D technology has not progressed as much as you want all to here to think (for sales), sure the GaN transistors that I first showed here years ago as a far better alternative for Class-D, you were quite negative about back then, and now you say you use them. How ironic.
I first showed the GaN power transistors from EPC (https://epc-co.com/epc) inventors of the Mosfet, to all here many years ago, and yes they have improved things a little, but the only one to use them fully and make a dent in Class-D’s Achilles Heel "switching frequency/switching noise/phase shift" has been Technics with the SE-R1 and hopefully the new SU-R1000 integrated has the same genes.