[Walt]

Arny Krueger wrote:
wrote

folks, I would like to run a line from my computer to my
stereo receiver so that that the computer can be used as
an input.

Can someone please tell me how long that line
can be without picking up too much noise.

The most common source of noise in lines between computers and stereo
receivers is ground loops which can exist in a line of any length from
inches to miles.

The usual source of the ground loop is the double ground connections
provided by the ground pin on the power cable for the PC, and an antenna or
TV set with antenna that is also connected to the receiver directly or
indirectly.

The easiest way to elminate ground loops are isolation devices for either
antenna lines or audio lines. A surprisingly good audio line ground isolator
can be found at Radio Shack.

Once you deal with the grounding issues, there are usually no additional
problems until you exceed several 100 feet or more.

Relatated question - how long can a speaker wire be?

As long as it needs to be, if you are willing to invest in cable with
sufficiently thick conductors. Practially speaking, again 50-100 feet need
not be a problem.

I'm assuming it's a lot longer?

It's generally more practical to extend line and mic level cables than
speaker cables.

What Arne said. Ground loops are the most common problem with long
line-level interconnects - length is not really the culprit here so much
as that with increased length comes the increased liklyhood that the
electronics at each end are plugged in to different electrical outlet
circuits each with their own ground.

The next most common problem is induced noise from radio frequencies and
AC - but this is usually a minor problem unless you live next to a radio
or TV tower or if you run the wires really close to high current power
cables.

Next comes high frequency roll off from cable capacitance. Very
predictable (and correctable with EQ), and only applicable at the
hundreds of feet or more.

So, the short answer is that line-level analog audio signals can go
hundreds of feet *if* you do a few things right. More than that and you
should think about another distribution method.

//walt