I recently upgraded my '13 SV w/o Bose and with Nav from its stock 'speakers' (if you can call them that). Not long after I got the car, I through in an old 200W SQ sub/amp I had laying around to help with the bottom end. However, I really wanted to improve the overall sound of the car, so I opted for a set of 4 inexpensive speakers (a pair of comps and a pair of coax) from Crutchfield to pair with another old 4 channel amp I had laying around. Speaker installation went pretty good (longest part was figuring out how to run from the x-over in the door to the new tweeters).
However, now I find that I get a noise coming through the speakers. I'd say it is ~500 Hz. It is only present when the car is in drive (it goes away when the car is in park). I suspect this is due to the frequency modulation for the AC synchronous motor. The noise also disappears when stopped at a light for a few seconds (when I assume the inverter switches off). The noise is not volume dependent.
I did the following troubleshooting:
Bypass the amp = No noise, low volume (4 ohm speakers)
Disconnect the high level input to the amp = Noise
I also scoped the +12 Vdc input (in case it was coming through there). I saw a 10 Hz waveform, but nothing new that was really visible between going from park to D. I've dialed back the gain on the amp all the way, which makes it bearable... but not the answer long term.
Anyone else have issues with noise after amplifying the speakers?