Tapping Rear Speakers for Powered Subwoofer

[River_Rat]

pardon my ignorance, but is this an acceptable place to tap into the rear speaker lines to connect to a powered sub with speaker level inputs? It seemed convenient while I was running the power wire.

 

[Stew]

That's exactly how I did it when helping my son add subs to his Jeep, it's been working fine ever since.

 

[sonic007]

Thats perfectly fine. The only reason to not do that in another car would be if the system was factory amplified.

 

[River_Rat]

Thanks for the input. This will be the first time I've ever done anything more than swap speakers and headunits, and I've never had a sub before.

BTW, can anyone tell me for sure which wires are positive and which are negative? I've read conflicting reports in various threads. Some say the stripe is positive, some say its negative, and then I've read that the the drivers side solid green is positive while the passenger side blue with black stripe is positive

 

[Stew]

You may have to look at the connector on the speaker for a +/- symbol, other than that the only way to know for sure without a wiring schematic is to connect a AA battery briefly to the speaker wires and note which way the cone moves. If the cone moves outward then the positive is on the positive, conversely if the cone moves backwards (toward the magnet) then the AA battery positive is connecting to the speakers negative terminal.

You probably want to have the speaker wire NOT connected to anything else but the speaker and AA battery to avoid back-feeding power to something and damaging components.

 

[sonic007]

In my wiring schematics for work, as far as speakers are concerned, all of the wires with stripes(varying colors) are negative.

 

[River_Rat]

thank you both for your help. I'm going to proceed as if all stripes are negative, as that makes the most sense to me. I'm not worried about polarity so much as knowing that all wires of a given pattern are the same.