Running Audio on Cat5 -- Possible???

[Ringo Langly]

Hi all,

I'm looking at wiring up my home with Cat5, and I have some rather odd
questions. First every room will be wired with two pairs of Cat5 cable
-- one definately for ethernet but the other I'd like to keep open for
other applications, which is the purpose of this email.

First... I want to run two phone lines on the Cat5 -- which will
eat-up two pairs and leaves me 2 more pairs. Is it possible to run
audio over those other two pairs? By audio, I mean wire-up a standard
Left and Right (RCA) jack to either pair for stereo audio. Is this
possible? I'll have a patch panel each cable will run to, so wiring-up
some audio cables shouldn't be too difficult. I'm just technically not
sure if audio will even run over a small gauge of wires for this length
-- which I'm looking at 50-60 feet. Also I'm not sure if there'll be
interference with two phone lines and two sets of audio cables running
through the same Cat5 cable -- given the cables can support the audio.

Thanks in advance for any ideas or suggestions. I'm just trying to
make wiring my home both easier and as simple as possible. Take care,

Ringo

 

[Dave Platt]

First... I want to run two phone lines on the Cat5 -- which will
eat-up two pairs and leaves me 2 more pairs. Is it possible to run
audio over those other two pairs? By audio, I mean wire-up a standard
Left and Right (RCA) jack to either pair for stereo audio. Is this
possible? I'll have a patch panel each cable will run to, so wiring-up
some audio cables shouldn't be too difficult. I'm just technically not
sure if audio will even run over a small gauge of wires for this length
-- which I'm looking at 50-60 feet. Also I'm not sure if there'll be
interference with two phone lines and two sets of audio cables running
through the same Cat5 cable -- given the cables can support the audio.

What you are seeking to do is possible, but how well it works will
vary.

If you simply RCA-terminate the two audio lines and go right into your
audio components, I predict horrible problems with crosstalk, and
especially with hum. You'll probably end up with a severe ground loop.

A better approach is to use a "balun" (balanced to unbalanced audio
transformer) at each end of each audio pair in the cable. A 1:1 audio
isolation transformer is really what you want... connect an
RCA-plug-terminated audio coax cable to one winding, and the RF-45
wire pair to the other winding. Using such a device will have two
effects:

- It'll prevent ground loops, by providing galvanic isolation of the
grounds in the two rooms. Ground currents can't flow across the
insulation between the transformer windings.

- It'll probably reduce hum and crosstalk, by using each twisted
pair in a fully-balanced mode.

You can buy commercial audio baluns (http://www.svideo.com/500019.html
is one such), or try homebrewing your own using audio isolation
transformers (e.g. Radio Shack #273-1374) and connectors and casing of
your own choosing.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Larry Brasfield]

"Ringo Langly" <rlangly@gmail.com> wrote in message
news:1107476394.323422.302780@z14g2000cwz.googlegroups.com...

Hi all,
Hi.

I'm looking at wiring up my home with Cat5, and I have some rather odd
questions. First every room will be wired with two pairs of Cat5 cable
-- one definately for ethernet but the other I'd like to keep open for
other applications, which is the purpose of this email.

First... I want to run two phone lines on the Cat5 -- which will
eat-up two pairs and leaves me 2 more pairs. Is it possible to run
audio over those other two pairs? By audio, I mean wire-up a standard
Left and Right (RCA) jack to either pair for stereo audio. Is this
possible?

It's possible. For line level signals, there will likely be
some discernable cross-talk, especially near the high
end of the audio range.

I'll have a patch panel each cable will run to, so wiring-up
some audio cables shouldn't be too difficult. I'm just technically not
sure if audio will even run over a small gauge of wires for this length
-- which I'm looking at 50-60 feet.

Not a problem unless you are driving speakers thru those
wires or hoping to get microphone input levels thru them
without some noise pickup.

Also I'm not sure if there'll be
interference with two phone lines and two sets of audio cables running
through the same Cat5 cable -- given the cables can support the audio.

Interference (aka "cross-talk") would be my only concern.

Thanks in advance for any ideas or suggestions. I'm just trying to
make wiring my home both easier and as simple as possible. Take care,

Ringo

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Randy Howard]

In article <1105gjvqmf5rr4a@corp.supernews.com>, dplatt@radagast.org says...

First... I want to run two phone lines on the Cat5 -- which will
eat-up two pairs and leaves me 2 more pairs. Is it possible to run
audio over those other two pairs? By audio, I mean wire-up a standard
Left and Right (RCA) jack to either pair for stereo audio. Is this
possible? I'll have a patch panel each cable will run to, so wiring-up
some audio cables shouldn't be too difficult. I'm just technically not
sure if audio will even run over a small gauge of wires for this length
-- which I'm looking at 50-60 feet. Also I'm not sure if there'll be
interference with two phone lines and two sets of audio cables running
through the same Cat5 cable -- given the cables can support the audio.

What you are seeking to do is possible, but how well it works will
vary.

Yep.

If you simply RCA-terminate the two audio lines and go right into your
audio components, I predict horrible problems with crosstalk, and
especially with hum. You'll probably end up with a severe ground loop.

It'll be far from ideal anyway.

A better approach is to use a "balun" (balanced to unbalanced audio
transformer) at each end of each audio pair in the cable.

Or you could go a simpler route, and know that it will work, with
off the shelf components. Check out the exstreamer and instreamer
products from Barix.com. Very cool, interesting developer community
working on bolting them into various home automation systems.

All you need is normal CAT5 (or higher) plugged into your network
switch wherever you want to run audio.


--
Randy Howard (2reply remove FOOBAR)
"Making it hard to do stupid things often makes it hard
to do smart ones too." -- Andrew Koenig

 

[The Spanish Inquisition]

Tomi Holger Engdahl wrote:

Line level audio will run though this wire this distance quite well.
Been there, done that. I have one system at my home where I run
the audio and video trough CAT5e wiring from my computer room
to my living room TV/hifi system. Cabling distance is about 15 meters.
No problems. The adapters are homebuilt (my own design).
The audio adapter part is built out of one of those RCA stereo audio
signal isolators sold or solving ground loop problems.
Basicly have opened one the device (it includes two audio transformr),
cut out the original signal out cable, disconnected the audio
transformer secondaries from original wiring completely and
soldered to two pairs on the CAT5 wiring. Works very well,
is easy to build (if you know how to solder), and cost
is very reasonable (those RCA isolators cost around 10-20 USD).
Just build two of theose adapters, one for each end of the connection.
Or go to a shot and buy a ready made box at considerably higher price.

I went the ready-made route and got two of these:

http://www.videocapturecard.com/svideobalun2.html

They transport the A/V from my PC across a distance of ~30 meters to a
stereo A/V modulator that merges the signal with my cable TV. It works
very well indeed.

Ximinez
--
Our three weapons are fear, surprise, and ruthless efficiency...
and an almost fanatical devotion to the Pope....
http://www.ai.mit.edu/people/paulfitz/spanish/t1.html