That's right, and it seems to me that is what's happening here, event with the amps away from the clipping point.
But they do tend to start hitting the clipping point when i run them at a constant level for long enough with very bass heavey program.
Can thermal compression be the cause of this?
How does the amp respond to coil overheating/impedance rising. I understand the total output power of the amp will drop, but can this make it hit the clipping point earlier then when it's running a cold coil?
I HIGHLY doubt the amp is changing anything because of the speaker changing impedance.
If anything, (if the clip light was actually looking at the output vs input signals-like old Crowns-but not most amps) the clip light should be going on early and then not as much with a higher impedance load.
I SUSPECT that the program material has changed (unless you are running the same material (meaning the same song the whole time) and is putting out a higher drive voltage-EVEN IF you are not changing your fader levels.
Here is one other "possible" answer (but I don't think it is right-but just throwing it out there).
Let's say that the clip LED is for a specific output voltage.
When the driver is cold, the impedance will be lower-possibly pulling down the available output voltage.
When it heats up, the impedance is higher-so the amp can swing more voltage. So the LED turns on.
This is a typical indication of a "sloppy" power supply.
I installed quite a few P7000s years ago. I found the sound to be very "loose" on the low end. Especially when compared to a Crest CA amp of similar power.
The Crest were A LOT tighter sounding and had more impact.
This was using the same full range speakers, but in different rooms.
But the results were the same each time.