Audio Systems: In phase IPA1204 Amp, 6x9 speakers, pioneer ts

Question
In my car I have a 4 channel In phase IPA 1204 2400W Amp running a Pioneer TS-W307D2 1200W Subwoofer and 2 Pioneer TS-A6903i 350W 6x9 speakers on the back shelf. The whole system set me back over £300 and was fitted by a pro so it wasn't a cheap job. However I've had nothing but trouble with my Amp. Over the past 4 months it's gone into protective mode twice. I don't play it particularly loudly yet it still goes into protective mode. I've tried turning it on without speakers fitted and it still doesn't want to come out of protective mode. Last time it broke I got it fixed but now its out of warranty and I want to know what might be causing it. I Can't think of any other information I've missed. Thanks for your time.

Answer
Amp sensitivity internal control can cause it to go into protection prematurely.  I don't think it is a "user" accessible control, however. Your installing dealer would be the one to check it.

These are the "external" causes of sending an amp into protection mode.

ONE: Impedance of the speaker load too low for the amp.
TWO: Shorted voice coil in a speaker unit.
THREE: Short on the speaker line (to chassis or across output).
FOUR:  Battery voltage drops too low when amp is delivering heavy bass.
FIVE:  Battery voltage goes too high (very rare condition!).
SIX:  Power overdrive to speakers causing amp to overheat.
SEVEN: Amp closed in with no ventilation and runs too hot.
EIGHT:  Bad/high resistance grounds or power wires from battery.

These are some things to check over.  

Sounds like a terrific system; we will solve your problem, just be patient.

Check out the above items, then let me know the rest of the story when you have found something.

C