Hi all -

I have just connected my PC to my home stereo. It works fine except for the low-ish humming I hear from the speakers. It's not usually audible with music playing. It does get louder when I turn up the volume. The noise is present (but much lower on my PC's powered speakers). However, the noise persists even when I mute the sound card entirely. I'm assuming that the sound card is picking up noise from the fans in the case.

I have -

Soyo K7ADA 1.0

Thunderbird 1.4

256 MB PC2100

Turtle Beach Santa Cruz

Windows XP

Does anyone know of a way to shield a sound card so it receives less interference? TIA

It's probably not the sound card getting interference but the cables.
Try getting shielded cables.
If you twist your cable a bit near the plug on your card does it still hum ?

Bad cables can also emit such hum.

edit - just saw that you say the hum is present on pc's speaker! Then it could be that you need to ground it (the sound card).

HTH,

Cat

Not the internal PC speaker, the normal sub/satellite combo I use. The hum remains constant unless I unplug the cables from the sound card.

The leads going out from your pc on the way to your stereo could be laying on or near some power wires. Is the hum a line noise? Approximately a 'B' note (60hz) musically? Yes, shielded cords of good quality sould be used.

But the pc speaker noise along with the rest ususally means that the grounding is not good. Running a ground wire from one case ground to the other may help.

Also in volume controls turn down all the inputs other than the ones you need and same for outputs. See if that helps.

Something that I encouter in PA equipment from time to time is that the ground lead on one of the devices needs to be 'lifted'. Try unplugging say, a cassette deck and see if hum persists. If so, try the turntable, one by one till you find it. If none of this works try a ground adaptor that eliminates the round plug from the socket. Try it on the stereo first. Sometimes on a 2 prong plug you can rervers or turn it around and the noise will go away.

Keep in mind if you have surge protection on your pc but not on your stereo, by being connected you've disabled the surge protection. They should both be through your protective circuit strip.

The hum persists even if I mute all inputs on the sound card. I'm using decent cables (nothing special). They're Phoenix Golds interconnects designed for use in a car, so their shielding should be OK. I am adapting them to a Radio Shack mini-to-RCA adapter.

I should mention I have seven fans (two in the PSU, one on the MB, one on the CPU, one intake and two exhaust) in my case. The create quite an amount of EMI/RFI, I would think. The T-bird gets quite warm you know... ;)

The cables are nowhere near power any power cords. I don't hear the hum through my headphones, but then again there's no amplification going on there....

I don't hear the hum through my headphones, but then again there's no amplification going on there....
Then it is definitely cables....
Headphones do require amplification though and a headphone output is not like a line out. A speaker or headphone out is pre-amplified on the sound card.
FTT gave you some solid advice there.
I would try changing cables and possibly losing the radio shack type ones.

Cheers,

Cat

A-ha!

When I unplug all of the rest of my components from receiver, the hum stops. If I reconnect even one of the other component's interconnects, the hum starts up again.

Both my stereo and PC are in surge protectors. The PC has its UPS, the stereo has a plain surge protector. Clearly some kind of ground loop. i hope a slightly more convenient solution than unplugging all other components. :D

Maybe a higher quality RCA-to-mini adapter would help. AudioQuest (http://www.audioquest.com) has one that uses a different grounding method...I think. :o :)

Thanks for the suggestions!

Try them through the frontside jack on your CD-ROM. Just where to go from there, well I'm still thinking... :rolleyes: If you smell anything peculiar, it's just me :)


Edit continued: The cables are fine then if the sound is gone when you stereo peripherals are removed. Try turning the plugs around on the offending component.

No hum when plugged into the CD-ROM's output. Unfortunately, MP3s don't come out either. Well, WMAs at the moment. ;)

I tried plugging in my receiver only, and directly to the outlet. No go.

All of the components are offenders. I'm guessing there's something weird with the ground path layout in the receiver.... :confused:

What do you have for choices in the back of your receiver? Can you try a tape recorder loop? Using the Tape in? It usually involves a front switch that pretty much closes the other inputs. This may help.

If the plugs on the other devices are unevenly wide, either cut the wider one down or use a ground adaptor and turn them around (hot for ground and vice versa). Have you tried this yet?

Also connecting a (not necessarily green) ground wire from one component to the receiver can help at times.

Are you saying "unplugging" from the wall or from the back of the receiver? If from the wall, you could use a terminal strip for your components and just flip the switch while using the soundcard.

Actually, the tape loop was the first input I used. It's the only one that was left open...

My receiver uses all electronic switching, so it doesn't have a separate tape loop switch. I have also tried plugging the PC into the AUX input with no success. When I said unplugging, I meant unplugging the audio connections from the receiver. Any time another audio connection is made the humming starts (even if the other components are unplugged from a power supply.

The auxiliary ground wire might be useful. I do have a phono input I'm not using....

If the hum is present on your PC when not connected to the stereo, and is present when anything else is hooked up to the stero, and not present when just the computer is hooked up to the setero you have some very funky household wiring issues.....one of those outlets used in this mess is probably not grounded and maybe has the hot/neutral reversed. If that is the case then one of you surge protectors is not doing any good.

Hm...maybe I'll invest in a cheapy outlet tester. There's a Rat Shack just across the street. :)

Further testing reveals that the PC causes buzzing in ALL of the inputs if other components are connected. O_o

Cheapy outlet tester...good idea.

I bet we are having some serious shortcut electrical install work done here......

Well, the landlord did the work.

Y'know, I'm a professional installer by trade....I can tell you that it's not that hard to do it right.....*grumble*

An update, if anyone's interested -

I put a ground breaker on my cable line and the humming went away. Freakin' Time-Warner.... :p

Not shoddy electrician...shoddy cable install.

Originally posted by mjc
Not shoddy electrician...shoddy cable install.

Yuppers. Unfortunately, that's about par for the course. If I recall we have two six-way splitters, a four way, and possibly a two way or two. :eek: It's a wonder I get any signal whatsoever. I was on the phone recently with a Road Runner tech who commented that my modem signal was very weak. I told him about the maze of wires and splitters and his horror was very audible.

So, I guess it's safe to assume that the cable feed isn't grounded properly. :rolleyes: