Preamp

Head Unit Preamp Outputs

I need to begin by thanking Richard Bevan, without information from his website I wouldn't have been able to perform these modifications. - Saab Audio Guide - Overview - When installing an amplifier there are two choices for inputting the signal to the amp, speaker inputs and preamp inputs. Speaker inputs are simpler to hook up, the speaker wires are cut and routed to the amp, which increases the signal and sends it back to the speaker through different wires. The drawback of this method is that the signal is amplified twice, first by the head unit and then by the amp, this creates distortion and poor sound quality.
Preamp inputs are the best method when installing an amp, a pure un-amplified signal is sent from the head unit to the amp. The sound quality of this method is far better than speaker inputs, but there is a catch for Saabs. All amps require RCA type wire for their inputs, the Saab head unit does not use this for its preamp output. At the right is a picture of the head unit with the output wire, it is and 8 pin wire that connects to the Saab/Clarion amp.

Model Information - These directions apply to owners of the SE model that comes equipped with the Saab/Clarion amp, door speaker and 8 pin wire. If your Saab is not equipped with the extra sound system then you will not have the 8 pin wire and must make or purchase your own. The only place that sells this wire with the 90 degree bend is Saab, and it costs $88. There is information on Saab Net on how to create this wire, but I am writing these instructions for Saab owners who already have the 8 pin wire.

To the right is a diagram of the 8 pin wire. The picture is oriented so that you are looking down on the wire with the 90 degree bend to the left (it is oriented the same way in picture 1). On Richard's site the diagram is of the holes in the head unit, so the pins appear reversed. The colored pins indicate the color of the individual wires inside.
     Mute - Orange
     Amp On - Red
     Not Connected - No Wire
     Signal Ground - Exposed Copper Wire
     Large Grey Wire - Contains The Four Speaker Wires
          Rear Left - Dark Green
          Rear Right - Grey
          Front Left - Light Green
          Front Right - Blue
          Signal Ground - Exposed Copper Wire Inside Grey Wire

Tools For Splicing RCA Wires Into 8 Pin Wire -
     Pair of RCA Female Connectors
     Razorblade, Tweezers, Pliers
     Electrical Tape
Directions - Start by removing the head unit, I used four "Shish kabob" sticks, insert one into each hole. Pulling out the head unit requires some force due to the tight fit, gripe it in the tape hole. Once removed several sets of wires are visible, the preamp wire is the only one on the side of the head unit. The other end of the wire is connected to the amp which is accessed by removing the kick panel on the passenger side. The panel is held in place by two hex screws and three plastic tabs, the bottom picture on this page shows the panel removed. With the wire removed you are ready to splice in the RCAs

Step 1 - Using a razor remove about 2" of rubber insulation from the wire. Underneath is foil wrapping, remove it to expose three wires, copper wire and string. Also with the razor cut the RCA cable so that it is at least 6 inches long. Slice open the rubber insulation to reveal the copper grounding wire and the inside wire.
Step 2 - Isolate the large grey wire, using the razorblade cut it open to reveal four wires inside wrapped in copper wire.
Step 3 - Separate the copper wire from the four colored wires.
Step 4 - Determine which wire you will be using. For rear speakers or subs use the dark green and grey wires, for adding a front amp use the light green and blue wires.
Step 5 - Isolate the wire to be spliced, in this case it is the grey (rear right) wire. Using the razorblade shave away the rubber insulation exposing the copper wire.
Step 6 - Wrap the RCA signal (inside) wire around this wire and reinsulated it using a small piece of electrical tape.
Step 7 - When both RCA signal wires are spliced and insulated connected the RCA ground copper wires to the exposed copper wire of the 8 pin wire. Then cover the entire area with electrical tape.

Conclusion - I am extremely happy with the sound quality. Before I was using speaker inputs which made the audio system sound cheap and high volumes produced distortion. By splicing into the 8 pin wire I retain all my fade and balance controls on the head unit. For anyone who is installing an amp I recommend this solution as the only way to achieve good sound quality.

This picture shows the wire reinstalled with the RCA splice and connecting wires. You may have noticed that I did not use the Amp On wire to turn my amp on. The reason for this is that the voltage is not high enough to turn on a standard aftermarket amp. The Saab amp requires a low voltage to turn it on so the Amp On wire carries a low voltage. For more information on finding a turn on wire refer to Installing Amps.

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