I ON the amp without a heatsink and the protection did kick in.
Probably better not to do that. If the protection doesn't kick in fast enough you could damage the chip.
the heat is coming slowly.
Seems like you need better thermal coupling from chip to heatsink, then.
If you're using mica and thermal paste, don't use lots of paste. Cover the mating surfaces fully, but with the thinnest layer you can.
If you're using a sil-pad, make sure it's very thin. And remember different makes and types will have different performance for the same thickness.
Make sure the chip is screwed down tight -- but not too tight or the body of the chip may get levered up and not make good contact.
Maybe consider getting one of those clips which press down on the body of the chip, although I've not found them necessary.
It should run cooler once you've got better thermal conductivity. If the heatsink warms up quickly and it's still too hot... well, worry about that if it happens.
Hope it goes well.
