Class D amp with sagging input voltage?

[eem2am]

On the Power supply forum, i hear that class D amps cannot handle an input rail voltage which sags on transients.

Surely that cannot be right?

Class D is run by DSP, and DSP is the king of digital filtering, which can surely filter out any deleterious sounds?

[wwenze]

Class D amps without using feedback to compensate for fluctuations in power supply have a PSRR of essentially 0dB, because output voltage directly related to power supply voltage.

Many class D amps do use feedback and have good PSRR.

[nigelwright7557]

Originally Posted by eem2am

Class D is run by DSP, and DSP is the king of digital filtering, which can surely filter out any deleterious sounds?

Class D is usllay either discrete or chip i.e. irs2092.
You would need to add a pre amp DSP to later it.

I design a simple class d amp that had no feedback. It had ramp generator, comparator, phase splitter into ir2113. Sounded fine but had some hum problems which i fixed with a dc offset pot on the input. It really needed -ve feedback to kill the hum properly.