Kai Klaas wrote:
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In class 'D' operation I can believe it just possibly, but in 25 years of looking at 'em. I have just never seen explicit "freewheel" diodes on an audio amplifier !
Sorry to harp on about this, but I have a feeling like we are living in parallel universes !

I have asked several professional audio designers and they too haven't seen flywheel diodes on audio amps.

Douglas Self's famous book on audio amplifiers shows none.

And my own John Linsley-Hood inspired amplifier - the illgotten end product of my final year project doesn't have them either.

Perhaps it might be needed on a transconductance amplifier, and diodes are almost certainly needed to protect input stages.

Also bear in mind that an audio amp has a low-ish slew-rate, since it has a finite and limited bandwidth. whereas an open circuited relay coil can have an extremely high slewrate, in a switching transistor circuit.

Steve