Home Automation - Line out audio over phone cable?

Author

Line out audio over phone cable?

Michael Burr

2008-03-19, 3:25 am

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.

Thanks,

Michael

Robert L Bass

2008-03-19, 9:25 am

"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.

--

Regards,
Robert L Bass

==============================>
Bass Home Electronics
4883 Fallcrest Circle
Sarasota · Florida · 34233
http://www.bassburglaralarms.com
Sales & Tech Support 941-925-8650
Customer Service 941-870-2310
Fax 941-870-3252
==============================>

Michael Burr

2008-03-19, 1:25 pm

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

> "Michael Burr" wrote:
>
> 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

Robert L Bass

2008-03-19, 8:25 pm

"Michael Burr" wrote:
>
> 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.

OK, not to worry, Michael. You won't fry the wires with line level audio.

> 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.

There shouldn't be a power issue with your plan. The only question is whether
you'll pick up noise. I'd try it using just the wire and see. Then if you
still need baluns you've lost nothing.

--

Regards,
Robert L Bass

==============================>
Bass Home Electronics
4883 Fallcrest Circle
Sarasota · Florida · 34233
http://www.bassburglaralarms.com
Sales & Tech Support 941-925-8650
Customer Service 941-870-2310
Fax 941-870-3252
==============================>

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