Hardwiring audio input in car amp and mixing

Thread Starter

john2k

Joined Nov 14, 2019
146
Looking for some help and suggestions. My car radio unit has a built in amp and has 8 wires going to 4 pair of speakers. It also supports a 3.5mm audio aux input. However, the 3.5mm aux input is treated as a source and I can only hear it when I'm in that source itself. So if I'm listening to the radio or any other source then I cannot hear the sound from the aux device. I need to somehow hardwire my aux input signal directly into the amp so that it mixes straight into the radio regardless of what channel I am in. Can anyone help advising me how I can even begin such a task? I'm thinking it would have to be mixed in somewhere in the amp inside the radio but have no idea where to even begin. I have a spare radio that I bought from a junk yard but the amp is blown on it so not sure how I can test.

Would really appreciate some help.

Thank you
 

Thread Starter

john2k

Joined Nov 14, 2019
146
You need to search for the service manual for your radio by make and model number.
Oh I wonder where I would find that? I've got access to the full manufacturer wiring schematic but it doesn't cover the internals of the radio. It only covers the connections going to and from the radio
 

Thread Starter

john2k

Joined Nov 14, 2019
146
Another possible solution I'm thinking is could I potentially add a mini compact 12v amp somewhere (one of those really compact ones) and somehow have my compact amp also feed audio out to the front two speakers? That would mean two amps (car amp plus the compact amp) will be connected to the front speakers. Not sure if that's even possible without damaging the speakers. Plus I'm sure some sort of auto switching between the two amps needs to happen
 

MisterBill2

Joined Jan 23, 2018
9,310
Presently most OEM car radios are serviced as an assembly, meaning that even if you have the circuit you could not get the parts.
In some installations the output amp is a separate board area, and if you locate that you may be able to discover the audio inputs.
Another choice would be a circuit called a hybrid, which allows signals from two sources to pass through without feeding back into the other input.

What sort of application is this for?
 
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