View Full Version : A few stereo suggestions

01-07-2005, 07:54 PM
I just spent the last day and a half upgrading the entire stereo system in my 89 750. I think I have some good suggestions for anyone considering the project.

My biggest worry was running of all the pre amp rca cables from the head unit to the amplifiers in the trunk. Then it donned on me. I am no longer using the BMW amp or CD changer already there. Within the big DIN cable from the cd changer to the old head unit is 2 good pre amp wires (along with some control wires). I simply cut off the din connectors, and soldered a new RCA connector to the mini coax wires within. That gave me two circuits for the subwoofer, now 4 to go for the main drivers.

How the pre amp wires worked for the stock head unit was a positive wire for the front left and right speaker with a common ground twisted together, same for the rear. Yellows for the front and blues for the rear. I was wondering how to make this work untill I opened up the amplifier I was using (Kenwood) and the grounds for the front are common, and the grounds for the rear were common. So, I soldered on rca connectors just as the stock unit was wired. For the front; yel/red right positive; yel/blk left positive and yel/br for both the front grounds.

I then went the trunk and soldered rca connecors on to match. The white wire was used as the amp turn on, just like the OEM setup. This way I did not have to run any wires from the head unit to the trunk.

I mounted both Kenwood amps up under the rear shelf in the trunk in the place of the oem cd changer and cell phone control box. I now have a 4 channel Kenwood running a set of Infiniti reference 5.25 component speakers in the front and a set of JBL 5.25 two ways in the rear deck. Then a Kenwood mono subwoofer amp running a 10" DVC sub in its own enclosure just sitting in the trunk. All being controled by a new Sony head unit.

I am very pleased with the system. It sounds better than any system I had previously had in a car. Infanatly better than stock.