VI limiter/ SOA protection For push pull Amps.

Hi all
I have recently been getting a couple of Ashdown MAG300 bass amps with blown output stages.
All due to either shorted speaker cables or soft shorted speaker voice coils. .
I recently built a speaker protect circuit based around the uPC1237 (photo), but did not make use of pin 1 that has the overload circuitry, as I’m not sure exactly how to use it.
Anybody have a circuit or idea how to add a VI / SOA limiter to these or similar push pull amplifiers. ??
Thank you all in advance.


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I found a schematic here:
which suggests the outputs are FETs without source resistors, so there's no easy way to monitor current and thus provide I or IV limiting - the normal circuits combine the voltage across the resistors with the voltage across the output device to provide a crude estimate of the instantaneous device power level.

All I can suggest is current limiting by using a lower voltage gate-source zener diode, limiting the gate drive.

The schematic shows 12V zeners with the BUZ901/906 FETs. Look up the curves for those devices, pick a gate voltage...