"Jon Elson"

Below 400 V there is probably no benefit to an IGBT. At 400 V and above,
MOSFETs start to show a higher on-resistance. The higher the breakdown
voltage, the higher the on resistance. IGBTs have a constant Vce drop of
about 2V or better, up to several times continuous rated current. That
starts to look real good in serious power devices like motor drives.

IGBTs in an audio amp sounds really odd to me, I'll bet a set of
FETs could have been dropped into it perfectly.


** Switching PSUs in many high powered audio amps use IGBTs - often in
parallel groups. The topology is a driven, square wave inverter - no
feedback or regulation is needed.

The dodgiest time is at first switch on, when the filter electros present a
dead short to the DC output. Usually, the drive wave begins with a very low
duty cycle ramping slowly up to full square wave. Drive frequencies are in
the order of 100kHz to 150kHz.

Readily available, low cost mosfets are not in the game.



..... Phil