Car Stereos: Pioneer DEH-p3000IB not running amp correctly, monoblock amp, pioneer deh

Question
QUESTION: hi. i just installed a Pioneer DEH-p3000IB into my car with a jl audio a1400 class d monoblock amp and 2 kicker comp 12"subs{4ohm} with 4 guage wiring. now the h/u works great but it is making the amp run in protect mode which makes the subs not work. they were running perfectly off the old headunit which i rewired up to test when i noticed this problem and they ran fine and so did the amp. i have read the manual without answers. i have tried adjusting everything i can think of and i know its not the amp or subs because they worked fine on the old headunit. thanks for your help. regards

ANSWER: Hi Chris,

Unfortunately, I don't have a good answer for this one.  I can't imagine any defect in a head unit that could trigger a "protect" mode in an amplifier.  From your amplifier's manual, it looks like the the "protect" mode is mainly caused by too low of a load impedance, or a high internal temperature.  There's nothing about your head unit that should be able to affect either of these conditions.

When exactly are you seeing the "protect" light:  is it on whenever the amp is powered up, or only intermittently?  Do you get any sound from the subs at all?

I can certainly see how a problem with the head unit could prevent output from the subs.  You'll want to make sure that your RCA cables are connected to the rear/sub output at the back of the head unit, and that the subwoofer mode is turned on.  If your cables are connected to the front output (or if the rear outputs are set for "rear" mode instead of sub mode), and you have the high-pass filter turned on, the result would be a lack of bass in the pre-amp outputs.  That could kill the sound of the subwoofers, but it wouldn't trigger a "protect" light.

You might want to try contacting JL Audio's tech support directly, through the link on their web site.  They'll have a better idea what conditions might trigger the "protect" mode in that amplifier.

Sorry I can't be more helpful.

Brian

---------- FOLLOW-UP ----------

QUESTION: the protect light comes on whenever a bass note is played then goes off then comes back on on the next bass note if that makes sense. i will try the rca's and check the settings but pretty sure the high pass filter is allready off. i did notice something in the installation guide saying the initial setting of the subwoofer output is monoaural but i cant find anything in the manual to change this. im going back to the place i bought it tomorrow and ask them and probly get an exchange headunit if no-one can figure this out

Answer
Hi Chris,

From the sounds of it, I think your RCA cables are probably hooked up correctly.

It's possible that the new Pioneer head unit has a higher pre-out voltage than the old one.  In this case, you might be able to help the problem just by turning down the amplifier's gain control. Also, Pioneer uses a default EQ setting that includes quite a bit of bass boost, so you might try leveling the bass settings in the head unit.

From what you've described, it sounds like the "protect" light might be caused by over-current.  That's usually the result of a load impedance that's too low.  If your Kicker subs are single voice coil 4-ohm type, then the final load impedance should be 2 ohms, which is fine for that amp.  If they're dual voice coil subs, however, you might have the amp connected to a 1-ohm load.  

Anyway, good luck in getting it figured out.  Hope some of this helps!

Brian