So, my stock CD player wasn't working (can't expect it to at 140k miles), so I bought a Sony stereo to replace it. It was installed about a month ago, and as of today, it started making strange noises when I would turn the stereo on.

I'm not sure the best way to describe it, besides it being a low, rumbling buzz. It seems to only start after the car's been running ten minutes or so or if the car's recently been running. Strangely, it seems to get louder while I'm stopped, and quiets down as I accelerate. Happens with radio and CD, and it's gone as soon as I turn the stereo off. I'm hoping it's a problem with the way it was installed or maybe the stereo, so I can get it fixed for free, but I should be so lucky.

I'm a total newbie at cars, so I'm hoping to get a few different ideas at what the problem might be. I spend at least 2 hours every day driving for work, so this is a pretty critical problem to me.

 

Take it back to whoever installed it. Touching anything that they can tell has been touch will cause them to either void your warranty or blame it on you.

 

does the pitch of the sound vary with the rpms? Sounds like your signal is picking up some noise that the stock subs are playing. Is it from the front/rear/all the speakers? Subs and tweeters?

 

Most likely the installer keep the factory ford amplifiers the problem is if he install some type of interface module to lower the high signal from the new radio, to the factory amplifiers, if the speaker wires from the new radio are wires to the amplifier with out any hi low interface , that will damage the factory amplifier, the first couple of days weeks they sound good and louder better than any factory radio but later, this noise problems appear

good luck and check behind the radio

 

something very similar to this needs to be behind your radio
http://www.pac-audio.com/productDeta...&CategoryID=26

 

there is little to no problem with wiring the speaker level outputs on a deck into the mach amps. They do not really use a true rca-level input and basically just pipe in the stock jbl's low powered speaker outputs. Those converters are ok but really do not do much for the mach system.