Anyone know anything about Active Crossovers (Car Audio)?

What up guys. I'm using the salvageable components of a fairly nice Stereo that was already in 489 when I picked her up. I've added some Boston Acoustic components up front, with full range rears, and a JVC KD-AHD59. The car already had an Orion XTR-12, a Coustic XM-3, and two Sony Amps (a XM-4040 and a XM-6020).

Here's my problem, when I got the car the I saw RCA's laying all over the trunk. When I looked under the parcel shelf, I noticed the XM-3 Active Crossover, and some other wires going behind a panel. Behind that panel was the Sub and two amps. So I thought "Dope, I'll just get a head unit and some new speakers, and hook all this back up". Not so fast Shooter.

The original setup appears to have been professionally installed, and 489 has one of the cleanest interiors I've ever seen (that's why I picked her up), so after removing almost the entire interior, I think I can see how they ran everything. It looks like they used the Factory Harness's rear speaker wiring for the front speakers. Joining the two together (somewhere) so they didn't have to run speaker wire from the front to the back. So the wires in the trunk that were originally for the rear speakers are hooked up to the XM-4040's outputs, and there is speaker wire they added going from the rear speakers to the XM-4040's outputs. So that seems pretty straight forward.

Now the original head unit had Preamp RCA Outs labeled Rear & Sub. So I'm guessing the Original installer was splitting the Rear RCA Out (either before or after) the XM-3 Crossover, in order to get four channels of audio (via RCA's) to the XM-4040 amp, which would then be distributed to each of the four speakers. But wouldn't that just duplicate the rear RCA outputs so you have front and rear speakers all broadcasting rear signals? I'm used to home theater systems, and have hooked up plenty of car stereos (albeit much more simple), but aren't there different sounds broadcast front and rear, that you would otherwise loose by simply splitting the rear RCA Outs?

This is driving me crazy! /ubbthreads/images/graemlins/banghead.gif I just want to know the traditional way to hook this up, so I can then start looking at the possibility of a faulty component. Thanks in advance, any help will be greatly appreciated.

 

[gvr4ever]

That was kind of hard to read. It sounds like he used a active crossover to control what went to the sub and the rear speakers. I'm sure the rear speakers still still had some sort of passive crossover on them.

 

[Rausch]

With an in line crossover, active or passive, you should not need an additional high or low pass (or bandpass for that matter) filter. The output to the sub should be low pass (steep slope maybe 18db/oct?) and the output to the rear speakers should be high pass ( maybe band pass, but doubtful), with a smoother slope 6 or 12db/oct...these are both fed from the outputs from the crossover?.

Not exactly sure what you are asking though, so don't know if that helps....

 

Well I guess my main concern is whether or not people "split" their preamp outputs with their crossovers. As in, I have a four channel amp (in addition to the two channel amp for the Sub), and the head unit has only Preamp "Rear" Outputs, and Preamp "Sub" Outputs. So originally it looks like he was "splitting" the "Rear" Preamp Output before the XM-3 Active Crossover with RCA splitter cables. So now you have the "Rear" Preamp Out's in four channels instead of two. Two for the "Front" input on the Crossover, and two for the "Rear" input on the Crossover. The "Sub" Preamp Output runs as expected, going straight from the head unit to the "Sub" input on the Crossover.

To make matters even worse I called JVC, since the Preamp Outputs on the new KD-AHD59 are labeled "Front" and "Sub" (instead of "Rear" and "Sub" like I've always seen in the past). This usually indicates that the "Sub" Preamp Output is selectable between "Rear" and "Sub". If that were the case I would just set the Rear/Sub Preamp Output to "Rear" and split that output with the Sub, thereby retaining my ability to Fade front and rear at the head unit (something I would not be able to do if I split the "Front" Preamp Output).

It looked like I had it all figured out, until JVC told me the "Sub" Preamp Output is not selectable between Rear and Sub. /ubbthreads/images/graemlins/banghead.gif

So it looks like I'm going to try splitting the "Front" Preamp Output before the Crossover, run the "Sub" normally, and then test the power, ground, and polarity of all the connections, and see what I get.