Amplifier on only with Radio

No sound from the speakers, except for the FM radio? Got an amplifier, factory installed or your own custom fit amp?

The amplifier works and sounds great but only plays on the radio setting. If you change the audio input to Spotify, YouTube, or any app that is not the radio, the sound disappears because the amp is now off.


An Amp makes a big difference to an Android headunit sound quality. You can use the S/PDIF low-level output from the head unit to supply the amp. The S/PDIF bypasses much of the android headunit [poor quality electronics and sends it to the amplifier. Your amp may have cost much more than the actual head unit. This makes sense; the higher quality parts in a good amplifier will pay you dividends in the improved sound quality and range of speakers it can run.

Only Radio

Having the amplifier work only on FM or AM radio is not very helpful and isn’t using the amplifier to its full potential. Not only that, the apps have no sound. No sound from YouTube, no sound from Spotify, no apps giving sound, not even the DABZ for DAB radio producing sound.

Simple Fix

This could be a simple fix if you only have just installed your Android head unit and found no sound except the radio.

The problem is you have used the blue ANT wire to trigger the amplifier. Either the ANT wire is directly connected to the amp trigger ‘on’ signal or it powers a relay that switches on your amp; this is the problem.

Android Headunit Tip

ANT wire is usually only live when the radio is on.

ANT wire is for the antenna power for the FM radio, not generally used and originally used to power an automatic retractable aerial. If you use ANT wire to power the amplifier, the amp will only have power when the FM radio is on.

The solution is to use the AMP wire connection from the head unit to trigger the amplifier, as this is live all the time the headunit is powered up. That way, the amplifier is on when you need it for apps, not just when the FM radio is on.


Now you know the AMP wire enables the amplifier by switching it on, you can change the wiring to use AMP wire to run the amp and insulate the ANT wire with some electrical tape to avoid shorts.

Wiring Guides

We have a complete wiring guide covering the wire colors for both AMP wire and ANT wires, along with all the speaker and power wires on an Android Headunit.

Wires in the speaker connections series

An staff blogger. I am a multi-skilled dogs-body, and I also make the coffee ☕ More about the coffee I make @

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