integrating amp into factory system

[Iron Giant]

I am trying to add an amp/sub to my completely factory system. The amp I am using has high and low level inputs. I would prefer if I could run low level inputs, and since the signal from the headunit to the amp should be low level, it seems like a valid possibility. What I am thinking of doing is tapping into the LR+/- (from the head unit to the amp) wires, and running parallel to a soldered rca plug which should be able to plug right into the amps low level inputs. Also, while I am asking, if I do have to resort to running high level inputs, do I have to "use up" one of my rear channels or will I run into difficulties if I run it parallel? I measured the amp resistance at about 12 ohms, so using ohms law the channel would be about 3.5 ohms which might be too low for the factory amp.
Anyone have any experience with this?

[netcsk]

That should work. Measure the input wires to the amp to be sure that they are infact low level; if they are, hook er up!

[Iron Giant]

That should work. Measure the input wires to the amp to be sure that they are infact low level; if they are, hook er up!

if it's low they should read <1v correct?

[StereoInstaller1]

Hi. Let me offer an easy, noise-free solution.

Use RCA inputs, but put chassis ground on the outer ring (shield). Use speaker positive (from the deck, before the factory amp) as center pin on the RCA. The white wire is remote...easy as pie.

I would recommend using a front speaker output to run the sub, though. That way as you fade forward (so you will actually hear the fronts) you will still have bass.

Luke

[Iron Giant]

I would recommend using a front speaker output to run the sub, though. That way as you fade forward (so you will actually hear the fronts) you will still have bass.

Luke

good call, I was thinking that it's in the rear, so why not hook it up to the rear channel...but now that I think about it I normally fade forward so 75% of the sound comes from the front soundstage. In the rear I guess I would be giving my amp a weaker signal to work with

[StereoInstaller1]

Another handy trick is to use a small 4 channel to run mids/highs...just choose one that has a "summed" output...look for 3 pairs of RCA jacks.

Then, when you fade from front to rear, sub levels will stay the same. Plus, you can adjust F+R levels independently.

Luke