Which factory speaker wires are positive, and which are negative on 1992 348?

I can't attest to the original wiring but it's easy to determine just by trial. If you hook them up backwards then you will drive the woofer portion backwards and on low frequency the woofer will be pulled in instead of pushed out. You can hear the difference immediately in a quality speaker. Even if you hook up one wrong the whole system will sound bad. If you can't hear the difference then you can watch the speaker and see which way it goes. You won't ruin anything in the head unit so you don't have to worry.

Most head units provide the same power to all 4 speakers and don't filter any frequencies front to back unless it specifically says and so it makes no difference which you use, front or back. All the frequency and power adjustments are done from the settings.

 

MY interior is completely out of the car and the battery is disconnected so I was planning on installing mine without paying attention to left and right and then, if they were put in wrong, simply reverse the wires on the crossover below the dash without having to dismantle anything to get to the speaker. Is this a good way to go about it. Is it bad for the speaker if it gets power/sound signal that is incorrect? Can it get damaged?

Thanks (I'm not a sound guy so I don't know)

 

There is no 'polarity' on speaker wires. The wires connect to a voice coil and move the coil either in or out depending on the direction of the current flow in the wire(as has been mentioned prev).

You cannot damage the speaker or the amp by wiring it either way. In one way it will be 'in phase' that is, the left and right channels will reproduce the sound accurately by altering the pressure in the speaker in correct phase with the way the music was produced. The best method is to use a dual channel oscilloscope to match the waveforms, and then attach the wires to the same terminal orientation on the left and right speaker. The simple way is to just hook them up, listen to a soft passage of music with a substantial amount of bass cleft in it, then swap them and determine which sounds best. Trial and error.....

 

As I recall the factory speakers don't have a + and - indication at the wire connection points. It doesn't matter which you hook up to which as long as it's the same both sides to keep the speakers "in phase" as described above. So if you run the Right Channel rear + wire from the head unit to the right hand wire connection on the back of the right speaker, just do the same with the Left channel rear + wire to the same right hand wire connection location on the L door speaker. Use an ohm meter to track each wire from the speaker to the plug where the head unit is.
If you carefully pry the plastic air vents on either end of the dash, you will find the microscpic tweeters. The factory wires these together with the door speakers, but if you cut the factory wires to the tweeters and attach your own wires then you can run those to the "front" channels of the head unit. That way you can use the "fade" control on the head unit to adjust the mix between the tweeters and the door speakers

 

I'm sorry to disagree, but this may not be the case. If you hook them up the same for left and right speakers, you may be out of phase. Think about the car, with the same exact speaker mounted in left and right side panel(or door as the case may be). The same connection on each speaker will pulse the left side voice coil out and will draw the right side voice coil in, provided the speakers aren't labeled as 'left' and 'right indicating reverse winding on the coil.

As long as the windings on the voice coils are exactly the same, the left and right channels will need to be opposed to present the correct phasing. The best method is trial and error, to avoid a lot of complex messing with speaker investigation.

 

Well to clarify, you are both nearly there.

If they are wired the same they will be electrically in phase, but not necessarily acoustically in phase.

If they are wired acoustically in phase they may be electrically out of phase.

None of these cars came out of the factory with any phase issues even crossing Ferraris minds.

I personally would wire them electrically in phase as from factory and then choose to alter the acoustic phasing if required, whether you will even notice whilst enjoying driving the car, I'm not sure.

 

I've never heard of specific right and left hand speakers with different coil windings. I believe they are spit out at the factory one after another and packaged in pairs like those below. If you look real carefully there is a tiny + and - mark on the wire attachment points, and they even make the spades different widths to avoid faulty instalation. I would recommend hooking your + and - leads from the head unit to the corresponding leads as show below, take a listen, then try reversing them. 99% of the time the first arrangment should be correct.
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