Stereo output?

Discussion in 'General Electronics Chat' started by RobWheatley, Jul 17, 2012.

  1. RobWheatley

    Thread Starter New Member

    Apr 19, 2011
    Hi All
    Need a bit of help if anyone can.
    I want to connect a car stereo (on a motorcycle) to my intercom system so that I can control the volume, stop the playback etc (I do not have it up loud and Can hear what is going on around me) but the car stereo output has seperate ground outputs for left and right (4 wires, two for the left and two for the right) the intercom only has a three wire input via 3.5mm jack plug.

    How can I connect the stereo to the intercom, I have tried using one ground, joining the grounds, using an earth from the radio chassis, diodes in the grounds but the sound is distorted, muted or i only get one channel.

    Any help would be great.
    Thanks in advance
  2. MrChips


    Oct 2, 2009
    Firstly, we will assume the four wires were meant to be connected to two speakers, two for the left and two for the right.

    You will have to do some experimentation.

    Connect the ground (body of the 3.5mm plug or jack) to the radio chassis.

    Get a 10 to 47μF 25V capacitor, electrolytic or non-electrolytic (non-electrolytic or non-polarized would be better) and use the capacitor to connect between the 3.5mm jack and any one of the four wires. If this works, use two capacitors, one for each channel and just find which two of the four wires give the best results.
    PackratKing likes this.
  3. Audioguru

    New Member

    Dec 20, 2007
    The speakers connected to the radio have both wires powered with signals having opposite phases so that the power is almost 4 times higher than normal. It is called "bridged" or "bridge-tied-load". The speakers do not haver a ground wire.

    One output can use one speaker wire and ground but the speaker wire will have DC voltage on it and might need a coupling capacitor to feed your intercom.