It is possible that someone else may have had this problem or talked about it but I have been having horrible trouble trying to find any information about my problem.<p>My S40 has the premium sound system installed and some of my speakers are out. On my doors the top treble speakers work on all doors however the speakers on the bottom of the doors only work on the two front and are out on the two back doors. My center appears to be working fine however there is absolutely no base in my car. I do not know if my amp is our of if my sub is out or what the problem is. Volvo is reluctant to give me any information without first charging me a fee and I do not know where to start. I have checked my fuses under the hood and under the glove box and they are all fine. <p>Like i said music comes out of the speakers that i have but the quality is poor. I had thought that maybe i just had blown the speakers however, they will come on evey now and then and i will hear base in my car and then it will fade back out. <p>If anyone has any sugestions about what I should do where I should look or where I should start it would be greatly appreciated.<p>Also are there any repair manuals avalilabe for this car becasue I cannot find any online and i would rather make repairs myself if at all possible opposed to spending my life saving at the volvo dealer since I am out of warranty.