Hum in Wires

[Guest]

Archived from groups: rec.audio.tech (More info?)

SOUNDCARD: Soundblaster Audigy
RECEIVER: JVC RX-888V

I'm running wires from my computer to my reciever. The outputs from the
computer are front L & R audio, rear L & R audio, subwoofer, and center
channel (5.1). These are all standard 3.5mm stereo plugs and connectors
(i.e. the front L & R audio are output from the sound card via one 3.5mm
connector to a 3.5mm plug). Front audio is on one plug, rear audio on
another, and subwoofer and center channels on the other (3 plugs). The same
connectors are used for the local speakers of the computer except the
subwoofer channel of the sub/center connect is not used, it gets its signal
from front and rear audio.

Each cable to the receiver is 25ft. These cables are 3.5mm stereo to
male-RCA ends. So the end of the cable from the computer's front L & R
audio go to the discreet front L and front R connectors on the reciever.
Likewise for the rear and sub/center.

There is a low frequency hum coming from the speakers connected to the
receiver that is not evident on the computer's local speakers when they are
connected to the soundcard. It is not very loud on the front and rear
speakers but is clear on the subwoofer (not suprisingly, it's low
frequency). It is there when no sound being played on the computer. If the
sub/center wire is removed you can still hear it faintly on the front & rear
speakers.

Is there any way to prevent or correct this?

 

[Guest]

Archived from groups: rec.audio.tech (More info?)

"Reginald Stanton" <reginaldstanton@cox.net> wrote in message
news:CtoLe.244$5U2.237@lakeread07...
> SOUNDCARD: Soundblaster Audigy
> RECEIVER: JVC RX-888V
>
> I'm running wires from my computer to my reciever. The outputs from
> the
> computer are front L & R audio, rear L & R audio, subwoofer, and
> center
> channel (5.1). These are all standard 3.5mm stereo plugs and
> connectors
> (i.e. the front L & R audio are output from the sound card via one
> 3.5mm
> connector to a 3.5mm plug). Front audio is on one plug, rear audio on
> another, and subwoofer and center channels on the other (3 plugs).
> The same
> connectors are used for the local speakers of the computer except the
> subwoofer channel of the sub/center connect is not used, it gets its
> signal
> from front and rear audio.
>
> Each cable to the receiver is 25ft. These cables are 3.5mm stereo to
> male-RCA ends. So the end of the cable from the computer's front L &
> R
> audio go to the discreet front L and front R connectors on the
> reciever.
> Likewise for the rear and sub/center.
>
> There is a low frequency hum coming from the speakers connected to the
> receiver that is not evident on the computer's local speakers when
> they are
> connected to the soundcard. It is not very loud on the front and rear
> speakers but is clear on the subwoofer (not suprisingly, it's low
> frequency). It is there when no sound being played on the computer.
> If the
> sub/center wire is removed you can still hear it faintly on the front
> & rear
> speakers.
>
> Is there any way to prevent or correct this?

Classic symptoms of a "ground loop". Usually caused by
the equipment at the two ends being powered from different
mains circuits, etc. Sometimes also caused by simple
pickup of interference along the way.

http/www.epanorama.net/links/wire_av.html#grounding

>
>

 

[Guest]

Archived from groups: rec.audio.tech (More info?)

"Richard Crowley" <rcrowley@xpr7t.net> wrote in message

> Classic symptoms of a "ground loop". Usually caused by
> the equipment at the two ends being powered from different
> mains circuits, etc. Sometimes also caused by simple
> pickup of interference along the way.

Exacerbated by 25 feet of unbalanced cable from a possibly weakly-driven
output.

geoff