Pre Amp Output Voltage on Stock JBL Radio??

[sundev2]

I decided to add an amplifier to my existing JBL system, and after much (but obviously not enough) reading, I decided to splice into my Pre Amp Output from my stock radio. From reading the wiring diagram, I'm fairly certain Im using the correct wires (spliced in near the passenger door trim), but when I read the voltage it registers in the Millivolt range. Does this sound correct? I would think there would be at least SOME voltage coming out of the pre amp wires before the stock amplifier??

Please help!

 

[buievonbozo]

I think, depending on what radio you have, the voltage on aftermarket head unit pre-amps is either 2 or 4 volts.

 

[riverwolf]

Even though the JBL system has an amp in the rear next to the subwoofer, it doesn't use pre-outs in the traditional sense. You're looking at a data signal, most of the audio processing actually takes place in the amp, not the head unit. You'll need to splice in using the speaker level outputs from the stock amp using hi-lo converters if your new amp doesn't accept speaker level inputs.

-Brent