I wanted to connect my computer to a new (for me) stereo system I picked up pretty cheap. The amplifier is an RCA AV 120 Watt amplifier and the speakers are SP120-10 3-way speakers. My computer is this.
Anyway, I thought the simple solution was to get a cheap 3.5mm stereo to RCA cable and connect it to the inputs of my amplifier. I connected it to the “Tape” of my amplifier since I don’t use it, but I get a very loud humming. I can play audio and it’s not too noticeable when the music is turned up, but when it’s paused or muted on my computer it is very noticeable and won’t go away. When I listen to the radio or CD it isn’t there at all. I also had an uncle connect it to his cheap laptop ($400 from Wal-Mart) and there was no hum. When I tap my finger to the stereo input that should be connected to my computer there’s a loud thumping or tapping which to me would indicate a grounding problem. If I disconnect the stereo connection to my computer there’s no humming only when I connect it to my sound card output, even if no music is being played on my computer. I have also connected it to my mp3 player (battery powered) and there’s never any humming.
The only thing that I can think of would be a sound card problem, but then my uncle has a significantly cheaper computer than me and his has no problems. I searched and found this thread, but I didn’t see any answers there.
Humm is almost always a grounding issue. Take a wire, attach it to the metal of the stereo components (like where a screw holds the top on the back) to the metal chasis of your computer. Indeed the more components you attach this way the better the results. My experience is that cable boxes provide a lot of grounding issues. Finally, if you’re really anal you can ground everything to the wall plug for best results.
Rereading I bet his laptop was running on battery when the hum wasn’t there. That’s a grounding issue solved by the wire I described.
Thanks, this seems to have worked. Attaching the wire between the chassis of my amplifier and computer got rid of the humming from my subwoofers and then I unplugged my TV from my amplifier and it got rid of the rest. Not sure why, but it seems to work for now. Thanks again.
I have ran some more tests and it seems that my cheap $100 5 year old TV it causing almost all the humming problems. Without it, it sounds great. With it, there’s significant humming. The TV is two-pronged. I have tried connecting it to another plug but not outlet. Will that make a difference? Any ideas?
ETA: Connected it to a different outlet and it made no difference. It is definitely the TV.
2 prongs = not grounded. Once again, if you have cable tv that may be the source of the issue. Try attaching the ground to the threaded outer part of where the cable or antenna goes in the back. Might do the trick and certainly won’t hurt. If you use a cable splitter for the cable before the tv there is often a place to attach a ground wire to the splitter. That will work too.