My question is, how do these affect power compression? At the shootout the tuba 24's basically showed no change when we exceeded 400w. Yet the lab 12's in your 12PI continued to gain in output far beyond their rated max. Is that box, heat sink, or both? My primary purpose is woofer protection, but the capability for more power is appealing also.

I've also built them for the betas in my tops. It's really stubby like the PI design.

For further testing I just ordered a wireless oven thermometer that I'm going to insert for real world testing just for kicks. I figure if it will put a signal through a BBQ grill and send it 100ft it will probably get it outside the box for me to read. If not, hey I needed a grill thermometer anyway.

The digital thermometer is a good start, as it will show you the temperature with and without the decice and you can compare the difference. I suggest heat soak tests where you run the woofer at high power levels for an hour or two. Measure temperature and check T/S specs. Then since you have the cabinets done, you might also check response of the system, and see how much it deviates from cold at various power levels.

In the case of loudspeakers, the voice coil resistance increases and you lose voltage sensitivity. You also waste energy through heat loss and the system parameters change. A condition of thermal runaway sets up just before failure, where the voice coil radiates heat into the magnet wheich then re-radiates it into the voice coil and it gets hotter and hotter. Anything you can do to get heat out of the motor helps prevent this.

Got it. Thanks.

You've got it. With this arrangement, you can increase power safely. Not only does it increase power handling capacity, but it also reduces parameter shifts caused by heat, because it helps reduce heat buildup. It is an intercooler, same thing, just a heat exchanger.