Amp not switching off
Amp not switching off
I‘ve fitted a powered sub into my S8. I took the RCA feeds and switched live from the 25 pin plug for the factory Bose amplifier. I tested the switched live before splicing and all was good. What’s happening now is the amp isn’t turning off even with key out. However if I unplug the RCAs or the power plug to the wired sub it switches off and remains off. I used pin 3 (AF earth) for the RCA grounds. Could this be the issue?
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Re: Amp not switching off
AF is floating ground used for RDS so yes.
Re: Amp not switching off
I remember reading about this on how it's not a true 'ground' but couldn't remember where. My audio knowledge is pretty basic so not sure what the alternative is. Can I use the ground for the RCAs on lets say the rear speaker grounds or will that not work?
Re: Amp not switching off
Your amp is incompatibile. Chassis ground and floating bose ground have difference in potential.
You could ground amp RCA to car's ground but then you'd end up with a massive pop sound each time you start the car which is not good for the speakers.
The solution i arrived at is to completely rewire the car's audio system to use chassis ground, meaning new head unit, new amp power, new wiring for power and preamp signals, and a big capacitor at the alternator to stop the alternator 'whine' in speakers, which is why audi used floating ground bose to begin with.
In D3 they went a step further and used fiber optic cable to achieve galvanic isolation.
You could ground amp RCA to car's ground but then you'd end up with a massive pop sound each time you start the car which is not good for the speakers.
The solution i arrived at is to completely rewire the car's audio system to use chassis ground, meaning new head unit, new amp power, new wiring for power and preamp signals, and a big capacitor at the alternator to stop the alternator 'whine' in speakers, which is why audi used floating ground bose to begin with.
In D3 they went a step further and used fiber optic cable to achieve galvanic isolation.