2019-07-22

The line-level signals enter the Comvette head unit through a 12 foot, 3.5mm stereo audio cable. The RCA jacks are snipped off and discarded and the cable is trimmed back to a length of 10 feet (to match the length of the other head unit cables). Then the bare cable ends are connected to the head unit as shown in the diagram below.

NOTE: Anything that provides line-level audio signals can be used as input to the Comvette head unit, such as a portable MP3 player, cell phone, laptop computer, etc. The Comvette head unit simply acts as an interface to the BOSE amplified speakers.

A Dual (Stereo Audio), 50K ohm, Non-linear, logarithmic audio taper volume control potentiometer is used to control the line-level audio signals entering the BOSE amplified speakers. In order for the potentiometer to control the volume level effectively, the audio source must provide line-level audio signals at 100% (maximum) output. The potentiometer allows the operator to adjust the audio signals to the desired listening level.

NOTE: The Comvette startup script sets the Raspberry Pi's line-level audio output to 100% (maximum) and the FM Radio module always delivers line-level audio output at 100%.

After passing through the potentiometer the signals exit through a GWH-342 wiring harness adapter and enter into the car's OEM wiring harness.

Head Unit Audio Wiring Diagram:

For more information on the OEM wiring harness and connectors see the C4e BOSE Connectors page.