03-04-15: Kijankiagree. There might a small change happening here - Sanders Sound Systems Magtech amps have a regulated power supply (& I believe Roger Sanders has applied for a patent for that?).
Bombaywalla, Linear power supplies have regulation in preamps, DACs etc. but MOST of power amps are unregulated because of the amount of heat dissipated in power supply (and loss of efficiency).
Look at fig. 2 showing how PWM signal can be obtained by just using linear ramp. Icepower modulator uses sinewave, has two feedbacks etc. - but only for improvements.thanks for this reference, Kijanki I'm quite familiar with class-D PWM using a ramp waveform.
http://en.wikipedia.org/wiki/Pulse-width_modulation
My question was using delta-sigma instead. There might be some info on that same page you sent the link for. I'll read up.
Also had a question re. how class-D PWM can be designed without feedback like you wrote in your initial post. Got any references that I can read?
My amplifier with bandwidth of 60kHz shifts phase of the 20kHz signal by 20 degree.agree! The "funny" thing here is that I wrote something very similar in another thread but had Almarg state a contrary view stating that it wouldn't be such a big deal given that the hi freq energy is much less at these frequencies. Perhaps that is true - it's true that the there is generally less energy at the high frequencies. So, even tho' your amp produces a 20 deg phase shift at 20KHz, it might matter very little(?).
What I wrote in that thread specifically was
....This also means that since the ARC Ref 150 bandwidth is just 3X (rather than 8X or 10X) the music bandwidth (of 20KHz) one can expect to hear the amp impart its own phase shift onto the higher frequencies of the music. This can manifest itself in a few ways - the highs could sound rolled-off or they could sound warmer or there could be less sparkle/shimmer compared to an amp of higher bandwidth..
Almarg's comments to my post:
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1423113432&openflup&50&4#50