Need to send an unbalanced audio feed over. A single Cat 5. Thought about not using any sort of transformer, just straight termination

Run is appx 100'

I have used this in the past with success.

[Link: snapav.com]

As have I for basic analog backfeed of audio for DA. No issues.

[Link: transformativeengineering.com]

Ive never used these, but they are available

[Link: smarthome.com]

It's a crap shoot.

The only way you are going to know if it's going to work is to try it out and be ready to balun the line if needed.

I've tried this very thing many times over the years. Sometimes it works fine without any interference. Other times the line hums like crazy.

tweetymp4 for the win.

I installed a camera at home one time just for the heck of it with a 100 ft run of CAT5. Two pairs took power to the camera. One pair brought the video back. The last pair brought audio. Despite the unshielded audio twisted pair traveling 100 feet snuggled up against a video signal, which has a BUZZ at 60 Hz, the audio channel was dead quiet as regards electronic noise.

What I used for connections were a stereo RCA cable cut in half and stripped back, wires twisted together and crimped inside these connectors:



In other words, paying no attention to noise AT ALL and using stupid low tech hardware, just being sure ground at one end connected to ground at the other end, it worked just fine. But yours might not, as tweetymp4 says.

So what if I want to run balanced without transformers?

How would you do that?

If the Cat5e will be there anyway, I guess the easy way to find what you need is to try it the way Ernie did, if you have a spare audio cable. Otherwise, Leviton and other sellers have the keystone ports and they do work as long as you don't have to worry about ground loops.

[Link: muxlab.com]

I haven't used the Muxlabs, but I have used lot of the Skywalker AV baluns with composite video and in one house, I installed four AV systems and a fifth audio system for the garage and back yard- I used keystone inserts for the garage and when the iPhone is unplugged, it hums. I used the baluns for the third floor system to receive the signal for the whole house audio, with a CE Labs distribution amp between the preamp and the balun. I also used the distribution amp's green video output to send a composite video signal from the security camera DVR, so they can view without needing a computer, laptop or phone. No hum, not weird noises and the third floor cabling is probably 100' long.

Can the signal be digital? You could use a digital balun. I tried a set in the second home for the same people and they worked great- cheap, too. Got them from Skywalker and I have one at the source end, one at the basement rack and as a test, I combined the wires in the Cat5e so it effectively made a Y cable, feeding the theater preamp with the third end.

Take a look at my link to te
Unless you mean actual balanced connections

Balanced means that each of the two conductors has the same relationship to ground. Typically that means neither is grounded and they're physically configured, meaning twisted, so both conductors also have the same capacitance and inductance to ground.

It is not necessary to use transformers to connect balanced things among themselves unless the CMRR of the stage fed by the signal is not good enough.

The pairs of wires I used were not balanced in that one of each pair was the ground wire. Luckily, no noise was induced into these pairs.

Personally, I would not attempt to use unbalanced CAT-5, but as others have pointed out, sometimes you could get lucky. One worry for me is that the ground loading could change over time and you'll develop a (potentially intermittent) hum at a later date. One scheme that hedges against hum (somewhat) would be to use three pairs in the CAT-5. Use one pair to bond the chassis together, then ground one wire in each of the signal pairs -- at one end only.

In any case it is very important that the CAT-5 be driven from a low impedance source. For example, a Sonos CONNECT would be a good choice for the driver because it's output impedance is uncommonly low. (You can easily drive headphones from this output.)

buzz, one important point about the installation I was talking about goes without saying, so I didn't say it: the camera's video and audio outputs were not connected to any kind of ground at the source end. I think this speaks to what you're calling ground loading, though I'm not really sure what you mean by that, or that it might change.

For video, we're sure as heck driving it from a low impedance source: 75 ohms. Perhaps it's a fluke that the audio was dead quiet, but maybe the mic's preamp (in the camera) has a pretty low output impedance.

By "ground loading" I'm implying that dramas associated with other equipment, such as appliances, cable TV connections, and such, can cause (or cure) classic ground loop issues.

While a camera will probably not be bonded to a ground local to the camera location, its own power supply (wherever located) may be involved in some sort of "loop".

I see. You're right, but I don't think the way I've described the camera connection I made, or any camera connection I've seen in the last few years, would contribute to the problem.

All the camera signal grounds are connected together at the DVR and all the power grounds are connected together at the power supply a couple of feet from the DVR, so there are two star ground systems right next to one another. That I've never seen grounding problems AT ALL tells me this is probably nothing to worry about. This includes a couple of three year old systems where high tide actually comes up on the sand six feet beneath the floor of one restaurant, and another one where the Marina water is some twenty feet from one edge of the restaurant. If you won't have ground problems in systems so close to the ocean, I doubt you'll have them anywhere.