Car Stereos: buzzing noise from my radio, dash radio, stereo shop

Question
I just bought an in dash radio from my 2002 ford focus... which has tv/dvd,mp3 and bluetooth in one... i installed the radio and it seemed to sound perfect with the car off, but when i turn on the car there is a buzzing noise... and when i drive the noise gets louder and the car goes faster....any suggestions.. please?

Answer
That is interference from your alternator.  There are two things to fix the problem.  First, you want to make your ground wire as short as possible to a steel part of the car.  Be sure there is bare metal where it is attached.  If there is still buzzing, you will need a power filter on your main power wire (the red one).  Most new radios come with this filter already on the power wire, but some don't.  You can buy them at a local stereo shop, and it will fix the problem for sure.  Hope this helps, Scott