If I have an aftermarket HU and have an amp driving the speakers, can I use one of the speaker wires from the headunit to give the stock bose amp for the bose sub a signal or does it have to be low level?

 

I believe the stock Bose sub amp takes a low-level signal and you will also need a low pass xover somewhere.

 

ChinozTL:
Okay so you have an aftermarket HU, and you have a separate aftermarket amp driving the speakers? If that's the case, and I assume you're asking this because your HU does not have a sub out (in which case you wouldn't have a problem). You can do one of two things...your HU outputs I assume 4 channels to the aftermarket amp? You'd merge those channels with a stereo->mono box and cross it low with a crossover and send it to your sub amp. You can't just tap a speaker, because if you say, tap one of the right speakers, you won't get any of the left channel bass, and vice versa. But if your HU has any sort of line out, pre out, or sub out...you'd just take that signal, cross it, and send it to your stock sub amp.

As for a quick answer to your Q, yeah, it has to be low level going into the stock amp, or you'll fry it.

Austin519

 

Ok here's the deal......the HU has 2 sets of RCA outs.......front ands rear. Both sets are being used to feed the amp for the speakers. Now I still have the 4 channel outputs from the HU itself which is 45 x 4. Can I just take 2 of those channels and use an LOC to feed the stock sub signal??

 

ChinozTL:
Okay I understand...your HU has 2 sets of RCA outs plugged into the amp feeding the speakers. You CAN use the outputs from the HU to feed the stock sub, yes. You'd take those, send em through a low pass crossover to cut out the mid and high frequencies, and then through the LOC to your stock sub amp. But what I'd suggest instead is to tap the wires coming from the HU's RCA outs that's feeding your aftermarket amp, run the signal through a stereo->mono block, then a low pass crossover, and then to your stock sub. Is it a little more complicated? Yeah...but anytime you de-amplify an amplified signal (aka the LOC) your waveform will get slightly distorted, as compared to the original...because distortion is introduced when amplifying, and again when de-amplifying...so that's twice you've introduced distortion just to have the same waveform. That's why I suggest the other way. But if you have an LOC, and don't mind SLIGHTLY less soundQ (don't worry it's not much), you can use that method.

Austin519