Audio Systems: 1991 Delco/Bose radio and amp system, chevy caprice, bose radio

Question
I have a 1991 Chevy Caprice with a Delco/Bose stereo radio system model #16080121 serial #1013987. This system emits a very loud, high frequency noise from the front speakers when ever it is turned on. The controls have no effect on the noise  volume or pitch. The noise is so loud and annoying the neighbors will come out to find where it's coming from! Can you shed any light on this problem?

Answer
Due to that system's age,I would guess the head unit and/or amps are blown. If you still want to use the original stereo, these guys can help;
http://carstereohelp.net/gotquestionsQ04.htm

Otherwise, I used to swap those out for people, using the proper install kit and bypassing the Bose amps. Made it so they could have any DIN sized head unit after that, and any speakers they wanted.