I am putting in an after market radio & it looks like the stock speaker wires on the car side only have left & right. Is this a correct assumption? Other wires look like a ground- brown, always hot-fused red, key on hot- thick red, & thin white wire, maybe for illumination?

I appreciate the help!

Rob

 

It may vary by model year, but on the old cars at least, there is a pot next to the hand brake that does the front to rear control. With a modern radio that has discrete LF RF LR RR outputs, you need to rewire the connections to the speakers pretty much from scratch, or just use front l and R and keep the old wiring and pot.

I would rewire and bypass or remove the factory amps as well.

I am not sure what "level" speaker or amp input, that the factory system needs, so be sure to verify that too if you are keeping the old system. It should be clear from how the old radio was connected.

 

I agree. Assuming pre-S4, there is an amp between the passenger seat and door sill. From there, the signal goes to the fader pot next to the driver's door sill(or maybe vice,versa, I forget). Any good modern head unit will have a better, more powerful amp and will handle the fade function. You'll need 4 speaker pairs to splice into the existing circuit either just after the fader or the old amp. BTW, a better head unit may very well expose weaknesses in your old speakers.
Good luck,

 

I did wire the speakers only left & right. I combined the front & rear left & front & rear Rt. wires. As for the amp, I did'nt know there was one & I just used the wires from the harness. It sounds fine. It is a pretty basic (not much wattage) Blaupunkt.

Thanks guys!

Rob

 

Rob - combining the speakers like that may cause an impedance problem. Depending on how you did it, this can cause lower power, distortion, and the potential to fry the amp circuits in your radio/head unit. You really should run them on L/R and F/R!

I have found an EASY way to track down which wire goes to which speaker. Take an old AA battery (preferably one that is a little week)...you can then touch the speaker leads to the battery and hear which speaker those leads go to.

 

The reason I did this is cause there is ONLY L & R at the radio harness in the dash. I may go deeper & track down the wires at the balance pot at the drivers floor. Thanks though, I appreciate the advice. The deck was cheap enough also! $69! Ya can't beat that with a stick!

 

1979-83 Porsche 928 Stereo Information
Constant 12V+ Yellow
Switched 12V+ Red
Ground Brown
Illumination n/a
Dimmer Blue
Antenna Trigger White
Antenna Left Rear
Front Speakers 4" Doors
Left Front (+) White
Left Front (-) Black
Right Front (+) White
Right Front (-) Black
Rear Speakers 4" Side Panels
Left Rear (+) White
Left Rear (-) Black
Right Rear (+) White
Right Rear (-) Black

 

looks the same to me, but it was listed different:

1984-86 Porsche 928 Stereo Information
Constant 12V+ Yellow
Switched 12V+ Red
Ground Brown
Illumination n/a
Dimmer Blue
Antenna Trigger White
Antenna Left Rear
Front Speakers 4" Doors
Left Front (+) White
Left Front (-) Black
Right Front (+) White
Right Front (-) Black
Rear Speakers 4" Side Panels
Left Rear (+) White
Left Rear (-) Black
Right Rear (+) White
Right Rear (-) Black