150v Mosfet @ 146v?

[theAnonymous1]

Whoa, I was wrong.

A 2Hz sine was able to drive the rail voltage to almost 90V without the over-current protection tripping.

It fried the 150V MOSFETs I had put in. They were working fine with the normal 73V tail voltage, even with a continuous 20Hz sine at almost full volume.

So this is a real problem, even with unregulated supplies. I don't think it is that big of a concern normally as no one in their right mind would let their woofers oscillate at ~2Hz, let alone at any significant volume.

[Eva]

Modify the amplifier, use the low frequency cutoff points from the various coupling capacitors to prevent excessive rail pumping.

Try to find a 200V replacement MOSFET with a fast body diode and low charges, even if it comes in another package, for example IRFB4227.

Paralleling more devices is likely to cause trouble due to the gate charge increase.

[theAnonymous1]

I have already decided to go with the IRFP4227PBF.