JL amp low impedence problem on startup


New member
Username: Cosmic

Post Number: 1
Registered: Sep-05
I need some help with the following problem I am having. First some system data

Kenwood 5028 Head
JL 1000.1 amp
(2) JL w6v2 12" in a sealed cabninet

The amp is connected to the sub outputs on the head, and has been properly gain adjusted with a 50Hz test tone track. The amp is power triggered via the key-on lead from the head.

The problem I am having is that if I start the car with the head unit on, (or perhaps from shutting it off, with the head on) the subs incur a weird squawking and the amp illuminates the "low impedence" lamp. If I turn off the head and turn the car right back on, and then turn the head on, the problem seems to stick around. If however, I turn the head off, and say the next day come back and turn the head on (after starting the car) it seems fine.

My interim fix has been to ensure that I always put the head in 'standby' (which shuts the amp off via the 12V lead) before I shut off the car, and to run the car for a few minutes before I turn the head on. This consistently prevents the problem from occurring.

Inevitably though, I forget to turn it off or something, and the problem resurfaces. Not to mention the turning on and off is exceptionally inconvenient.

I should add, that I

My current suspicion is that the R.I.P.S. system in the amp might be getting confused by less than full voltage at startup, and that in turn confuses the circuitry, and it somehow computes a low impedence on the sub side.

Anyone experience anything like this? I would love to solve this problem.


New member
Username: Cosmic

Post Number: 2
Registered: Sep-05

Gold Member
Username: Jonathan_f


Post Number: 4817
Registered: May-04
Simple things first, check your speaker wires and the impedance of the subwoofers. How do you have them wired, BTW?

Next thing I would check is your head unit. Try connecting a switch and an alternative 12V source to the amplifier and see if the problem persists.

The RIPS system monitors input voltage and output current. If the low impedance light is on, it is usually due to overcurrent in the output devices, which is usually due to a short at the speakers, stripped or frayed wire, burnt voice coil, things like that. When you just start the car, though, the head unit shouldn't send a remote signal to the amplifier until the car is fully on, in which the voltage would be acceptable at that point, and regardless, the amplifier has protection that will not allow it to operate under 10V.

If all wiring is good, I'd look at the head unit first.
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