Question about my stereo

[PZR]

Hi guys I have a question about my household sound system and as its so hard to get someone intelligent in a shop these days I thought I would ask here.
In the the headphone plug on the back of my computer (the green one) I put a double adaptor which I think is a RCA adaptor. It takes the common red/black cables that you get in stereos. From that I ran a standard RCA (?) cable to the back of my stereo to the graphic equalizer tape play sockets. Now it works ok and I can hear the music I want to play but I am getting what I assume is interference from the computer. It can be heard as a loud humming predominatly when the volumn is turned down but it is still there when I turn the volumn up. It does the same thing no matter which plugs I try it in in the back of the system.
My question is how do I eliminate the interference.
Or does someone know a good site to find out this type of answer as this type of stuff is outside my knowledge base
Thanks
PZR

[davo]

guess from someone who doesnt really know and shouldnt be giving advice: could it be caused by the impedance being different? I remember being told never to plug in speakers from different sets with different impedance into the same amp. wonder if its because of that kind of thing, and if it is how would you change it.

after all that, maybe its just a dodgy cable *shrugs*

[Switch]

I know exactly what you mean, i get that through my stereo at home, but i just turn up the music so i cant hear it
My mate had a pretty fancy stereo in his car when he was at school, and he used something that stopped interference from the engines electronics.
Im assuming you can get something that does the same for computer signal interference?
Thats my idea anyway, Good luck

[Salival]

In a car, this kind of interference is commonly referred to as a 'ground loop.' I'm not 100% sure what causes it, but it has something to do with the way components are earthed.

I don't have a solution for you I'm afraid - maybe Google can help - but I'd be very careful connecting a stereo up to anything that generated ground loop interference as it's effectively some kind of short, and can send weird voltages through stuff.

[cs363]

In a car, this kind of interference is commonly referred to as a 'ground loop.' I'm not 100% sure what causes it, but it has something to do with the way components are earthed.

I don't have a solution for you I'm afraid - maybe Google can help - but I'd be very careful connecting a stereo up to anything that generated ground loop interference as it's effectively some kind of short, and can send weird voltages through stuff.

OK, firstly check that your cable has the same ends as the one in the attached pic - pay close attention to the one that goes into the PC.Make sure it has the three sections to the plug (seperated by little black insulating rings) these three sections are your earth (x 1) and left and right outputs. If the plug doesn't have three sections this may be your problem as if it doesn't it's most likely a mono plug and you are sticking it in a stereo socket.

You are connecting it to the correct socket (the green one).

If the above is OK, then try a different set of RCA's on your stereo as some (particularly tape decks) have different input/output ratings to say AUX or CD sockets.

If that doesn't work check your sound set up in control panel on your PC. Oh, and one more thing - do you have your normal PC speakers plugged in? If so, try unplugging those.

Hope that helps, I'm no expert but have struck similar issues myself.

[Jeremy]

Are both the computer and the stereo plugged into the same power socket? You can get random stuff happen with the ground loops if they aren't, because all grounds aren't the same (random thing in the IEEE computer magazine about it which then bitched on about how this shouldn't be a problem anyway it's because of poor design on the components behalf).

[Gremlin]

mute your line in/mic as well, see if it makes a diff

[cs363]

Another thought - does your PC have onboard sound and a sound card?
If you don't know what I mean, check the rear of your PC - are there two lots of sound inputs/outputs (green and pink (or red) sockets usually) if so make sure you are connecting to the right one (try both if in doubt) and make sure nothing is plugged into the other set of sockets.

[PZR]

Thanks guys for all the helpful advise it was just what I needed. I bought a new RCA cable because I needed one anyway but it did not fix the interference but the helpful guy at Jaycar Manukau suggested I try an isolation transformer which plugs in line on the RCA cable and that fixed it a treat and only 25.00. I adjusted the control panel levels and that bought the low volume up so I can hear it and my stereo really cranks it out now so I am wrapped. A big ups to Jaycar for their great service (with money back if I hadn't needed the transformer) and so some advice from you guys
Cheers
PZR

Oh yeah and Sunday looks like a day to ride. Oh Yeh!!!

[cs363]

Sweeeeeeeeet!!

[avgas]

its easier to fix sitting in front of it - your "noise" could be anything from poor contacts on the 2.5mm jack to the dull 1/3 hamonic from the power suppies near where your cable is.

Its kind of like asking someone - my bike feels funny when i sit on it, seems to run ok - just feels funny when i sit on it.