Porsche 928 Electrics

Electrical information & supplies for late model 928s

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Seat Back Mounted Amplifiers:

These amplifier mounts attach to the rear seat backs - vertically when the seats are in the normal up position.

I can't take all the credit for these since one was already mounted on the car when I bought it... Obviously custom made by a good audio shop... however I disassembled it and reinforced it while cloning it for the other rear seat. By that point it had already survived probably a decade of use - but it was not as strongly built as I had assumed from this.

I did have to modify the inside dimensions of the new one for the slightly different amplifier size. It also needed  re-upholstery after years in the sun - so both now match perfectly and match well in my all black interior. 

This photo shows one half upholstered mount & the wooden frame for the second one

Here is a photo with both amps installed before the addition of the stealth speaker cloth,
They exactly match the profile of the seatbacks...

Here are the 2 amplifiers prior to installation - Top a/d/s/ 425X and Bottom a/d/s/ P440.2

Both these amplifiers have built in electronic crossovers and bridges. I use the P440 to drive 4 channels:  the front door pairs & B-pillar pairs and the P425X to drive 3 channels: the subwoofer (2 channels bridged) and the rear quarter-panel pair. I feed the amps from an a/d/s/ 642 CSI electronic crossover & mixer mounted under the driver seat that connects to the navigation head unit & CD changer, bluetooth phone system, Valentine 1 audio alerts and iPod interface. This also has a direct bass level control (mounted to the rear of the handbrake cover)

The amplifiers are powered by a specially designed audio power supply conditioning system. This involves an audio fuse (40A Maxi-ATX fuse), diode isolation from the alternator/battery, a 0.5Farad decoupling capacitor to the amps and series noise suppression chokes and decoupling capacitors to the head supplies. Most of his circuitry is installed in the battery box and/or behind a custom built panel above and in front of the spare tire. This is a very tight install but needed to installed very near the battery and amplifiers for optimally short wiring runs.

Copyright (c): Alan Moore 2006, 2007, 2008, 2009       Page Updated: 04/03/2009