I just installed an Alpine M-200 Amp and a Alpine 10" Type R sub in my 98 Jetta with its stock head unit, speakers, and cd changer. The amp is hooked up to my rear speakers for signal, you know. It sounds great, but if I shut off my deck, the sub starts to "Hum". The power for the sub is "on" only when the ignition is "on". What is my problem, and what should I change?

 

Most likely you hooked your amp triger up to a ignition source. This would explain why you have a hum with your radio off. When your radio is off the amp is still on because the ignition is still on but no signal going to the amp with will cause it to hum.

 

Most likely you hooked your amp triger up to a ignition source. This would explain why you have a hum with your radio off. When your radio is off the amp is still on because the ignition is still on but no signal going to the amp with will cause it to hum.

 

What should I do? BTW, Thanks for the reply.

 

Most factory decks have an antanae power up wire.
My '97 tercel, which does not have a power antanae, had a few unused terminals in the wire harness. I connected my volt meter to the ground and went through the different prongs looking for 12v while the radio was on and nothing when the radio was off. I found the 12v, and used a nail as the insert, soldered a wire to it and ran it to the amp. Now the amp powers up when the HU is on and powers down when it is off.

If your Jetta has a power antanae, simply run the wire from there to your amp remote.

 

Yeah I was lucky. I think that year the tercels, corrolas and camrys all had the same radio it was just a matter of plugging it in. Since the camry had the power antanae, my radio also had that feature.

Something else you can do is install a simple toggle switch in the relay line. When you turn the deck off, flick the toggle switch. Yeah, I know its two things that you have to do but at least it gets rid of that hum.