In article ,
wrote:

phil wrote:
Have just noticed that my new ASUS A7N8X-E Deluxe m/board (with
built-in nVideo nForce sound circuitry) puts out a bit of 'bus noise'.
I've only just noticed it today when using headphones for the first
time on this setup.

The Line Out of the sound circuit is connected to the Aux input on my
Hi-Fi's amp.

I *used* to have this problem on my old AWE32 ISA-based sound card (on
an ABit BH6 m/board), but muting the Line In fixed that. However,
muting/adjusting the volume settings for the various I/O on this new
board makes no difference to the 'bus noise'.

I'm sure it's not my Hi-Fi at fault, or cabling, or headphones etc
because, as noted, I eliminated the problem on my previous setup.

Any thoughts please anyone on a solution?



Ta,
Phil


Try placing one of those snap on magnetic things (sorry forgot the name,
rounded magnet in plastic) it shall reduce the noise problem.
I had to do that here on the cable that connects to the motherboard from
my case connections.

Minotaur

You are referring to a ferrite bead. Beads are used on some external
cables, and usually have a plastic coating on the outside, as the
ferrite is pretty brittle stuff, and would chip if hit or dropped.

A ferrite bead functions electrically, as if a resistor has been
inserted in series with the wires that pass through. Each time
a wire is wound around the bead, increases the effectiveness of
the filter. I.e. Wrapping a wire around a ferrite toroid three times
gives three times the effect of just passing the wire straight through
the toroid.

Note that ferrite is not exactly the same stuff as the toroids
used to make power for the Vcore of the processor. Those have
powdered iron in them. Ferrite is the same stuff that old
transistor radios used for their antenna windings.

A ferrite bead would stop high frequency noise at the point
the bead is placed, but the wire after the bead can still function
as an antenna. I guess that means the best place on a cable
inside a computer, would be near an input connector, if anywhere.
It is hard to say whether your average ferrite would cover the
frequency that is in the wire in this case.

You cannot apply ferrite beads to just any old wire. For example,
if you placed a ferrite bead on a high speed data cable (like
an unshielded length of SATA cable), that would kill the data
transmission on the spot. A bead has to be selected based on
the desired frequency you want to stop - using them on data
cables will degrade the squareness of the square waves, unless
you've selected the right ones for the job (i.e. ferrite freq
higher than fundamental plus harmonics of the data signals).

For some real info, try this site:

http://www.fair-rite.com

This is an example of a product you can fasten around a wire,
like say a line cord or something:

http://www.fair-rite.com/19mm%20Snap-On.pdf

HTH,
Paul