How to add a subwoofer to an Android head unit
The subwoofer output is A16 on Harness A. It breaks out to two green RCA plugs on the harness, both carrying the subwoofer signal. It is a dedicated output, so it does not use either of the front or rear pre-out pairs. The turn-on lead is the blue wire on A1, the same one an external amplifier uses.
What this gives you
Low end that a door speaker cannot produce, without giving up any of the four channels feeding the rest of the car. On a diesel 70 Series most of what gets lost on the highway is the bottom of the music, because that is the part sitting under the engine and tyre noise.
Before you start
- Harness A, the front audio pre-out and AUX harness. It is supplied with the unit.
- A powered subwoofer, or a passive sub and its own amplifier.
- One or two RCA leads, depending on whether the sub takes a stereo or a single input.
- A power and earth run to the sub already sorted, since the head unit only supplies signal.
Step by step
- Find A16 on Harness A
A16 is the subwoofer output. It breaks out to two green RCA plugs on the harness, both carrying the subwoofer signal. Green is what tells them apart from the white and red pre-out plugs on the same harness.
- Run it to the subwoofer input
A sub or a sub amplifier with two inputs takes both green plugs. One with a single input takes either of them. They carry the same signal, so there is no left and right to get the wrong way round.
- Run the turn-on lead
A1 on Harness A is the external amplifier control and the wire is blue. Take it to the remote terminal on the powered subwoofer or the sub amplifier. This is the wire that stops the sub sitting powered up all night.
- Set the crossover on the head unit
The unit has a subwoofer crossover and level control of its own. Set the crossover first so the sub is only being asked for the bottom end, then set the level.
- Set the sub gain last, with everything else already set
Get the rest of the system where you want it first, then bring the sub up until it fills in underneath rather than sitting on top. A sub you can point at in the mix is set too high.
- Check it against a track you know well
Something with real low end you have heard a hundred times tells you more than a bass test tone, because you already know what it is meant to sound like.
If it does not work
- No output at all: check the green plugs are on A16 and not on the AUX audio input on A5 and A3, which are also on Harness A.
- Sub stays on with the ignition off: the turn-on lead is on a permanent supply instead of A1.
- Sub thumps on power up or power down: that is usually the turn-on lead timing at the amplifier, not the head unit output.
- Boomy and one note: try the sub in a different spot before touching the settings. Position changes low end more than any control does.
Worth knowing
The sub output is separate from the four pre-outs and from the 5.1 centre channel on C2, so a subwoofer, a four channel amplifier and a centre channel can all run at once off the supplied harnesses.
Related guides
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