Help. How in the world is this wiring done? (Factory speaker components)

[bikinpunk 10+ year member]

I'm helping a friend hook up a basic 4-channel amp to power all his door speakers. My problem is that his door speakers are STOCK component sets (we're not doing aftermarket right now). Both speakers have a 4ohm load (Pictures 1 & 2). I've pulled his door apart and even his carpet and am completely lost on how to wire this to a 4-channel amp. I was expecting to find a passive crossover of some sort in there somewhere and have no luck. Instead, his tweeter & mid both have Green/Light Green wires (Picture 3). They run separate and appear to join together before they make it out of the Door grommet and into the car itself (Picture 4).

In the 1st picture there appears to be a capacitor on the tweeter. If so, I would assume this is what takes the place of the passive crossover. Even still, how does this load affect the wiring? It seems that if they are ran in series or parallel instead of through a crossover, the produced impedance would be 8 or 2 ohms load produced at the source.

I called a local shop and spoke with the installer. he said that the tweeter has no impedence, and thus the load seen at the headunit is 4ohms (due to the speaker only). This makes no sense whatsoever to me.

Can someone explain this to me? The amp we have can do 40 x 4 @ 4ohms, or 50 x 4 @ 2ohms so if these are in parallel that's fine. Still, how in the world is this wired? I'm lost.

Pictures:

Tweeter w/Capacitor

Door speaker

Wires joined to 1 set

Wires (in foam) coming together in door

Click to read more...

 

[jdawg 5,000+ posts]

your looking at the crossover of a stock system in the first pic lol, a capacitor, nice huh? Just tap into the factory wire, and check the impedance with a dmm

 

[bikinpunk 10+ year member]

your looking at the crossover of a stock system in the first pic lol, a capacitor, nice huh? Just tap into the factory wire, and check the impedance with a dmm

lol, thanks.

A guy in DIYMA explained the setup very well. I'm going to put his response here so if this question is searched for later there will be some solid reasoning behind "just wire it".

If I understand you correctly, it seems that the tweeter and midrange are running off the same green/ltgreen wire pair. The passive crossover essentially IS the capacitor (first order highpass filter) and the two speakers are wired in parallel. Maybe a little cheesy, but it is what it is.
The installer wasn't too far off the mark -- the load that the tweeter provides is rather insignificant. The capacitor (or any passive crossover for that matter) causes an increase in impedance at frequencies that it's filtering out. So at high frequencies the tweeter impedance is 4 ohms; at low frequencies it increases substantially. Similarly, the midrange has an increasing impedance at high frequencies that's inherent to the speaker itself (because of its voice coil's inductance). So at low frequencies, the midrange's impedance will be 4 ohms, but at high frequencies its impedance increases substantially. Because of this, there aren't any frequencies where the two speakers would BOTH be at 4 ohms at the same time -- when the tweeter's impedance is low, the mid's impedance is high, and vice versa.

So basically don't worry about the impedance of these speakers. The crossover is there, even though it's minimal.