Re: Line out audio over phone cable?

[Michael Burr <mburr@xxxxxxxxx>]

On Wed, 19 Mar 2008 12:28:34 +0000, Robert L Bass wrote:

> "Michael Burr" wrote:
>> Hi all,
>>
>> I'm working on a whole house FM transmitter project and would like to
>> mount the xmitter in my cupola to get it good and high.  So I need to get
>> the audio line out signal from my wiring closet up there.
>>
>> I'm considering pulling pairs 3&4 off a twisted 4-pair phone cable and
>> using on one line from each for left and right channel, and combining the
>> remaining leads from each pair for ground.  The run total run distance
>> would be approx 35'.
>>
>> Has anyone done something similar?  Any thoughts would be greatly
>> appreciated.
>
> Michael,
>
> There are several ways to accomplish what you want.  One simple methods is to
> send speaker level audio up to the cupola and reduce it there to line level
> using an audio transformer.  Another option is to use baluns at each end.
> Third, you might be able to use the twisted pair cable as is for line level,
> depending on how much and what kind of noise is present.
>

Thanks for your thoughts Robert.  I thought I'd start with line-level and
work my way up to speaker level if signal quality becomes an issue.

My biggest concern right now is wanting a "sanity check" on the idea
regarding form and current - don't want to fry wires in the walls.  As I
understand it - typical current between line-level devices is in the
very low ma range and my 24G solid copper wire can take at least 500 ma.
One end will be line-out from a PC sound card and the other the FM
transmitter.  I haven't found specs on it input impedance, but it has
typical line-in and will accept even MP3 players as input.

Michael