just installed a pioneer amp for my back speakers. the speakers sound great, but there is a continuous high pitched sound coming from the back speakers that increases as my rpms increase, i was told it was my alternator going out... is this correct?

 

sounds like engine noise introduced into your audio system. Do you still have the stock stereo? If so did you use a high to low RCA converter? The farther from the head unit you convert the signal the louder that engine noise will be. So if you converted it at the amp(in the back) it will be really loud, If you convert it in the front next to the stereo it will be pretty quiet. However you can try one of those engine noise suppressors

 

You can also buy an engine noise suppressor or filter as mentioned above.

 

check your gound wired for your amp, make sure you have a good ground

 

Those noise suppressors suck. It's probably a crappy ground. Did you do the install yourself or did you have someone do it?

 

I had the exact same problem when I got a cheap amp off ebay. The only thing I knew to do was buy a small but good amp that didn't produce that effect. I got an MTX, only 200 watts and it was all i needed and i had no problem. You may wanna listen to those other guys tho if u don't wanna just do that. I don't know why a pioneer would give you any problem with that tho. the amp needs a filter for this, so far as i know, but i could be totally off base.