Combining two audio signals (with standard 1/8" audio jack)

Factual Questions
1

I work in a movie theater as a projectionist. It’s a good job, but I’m alone all the time, and am thinking about getting an MP3 player to help pass the time. The only problem is that the theater’s main means of communication is a walkie talkie, and I need to keep an ear out for it.

What I need is something that can combine the stereo signal from the music player and the mono signal from the walkie talkie into one that I can listen to over the headphones.

Or even better, something that monitors the walkie’s signal, and interrupts the music when something is broadcast over it.

I’m pretty certain this isn’t something that’s sold in stores (at least not cheaply), but if someone can give me ideas, I could probably get the components and build it myself.

2

Are you certain you can hear the two-way on normal headphones now? Sometimes they use odd wiring and/or connectors and/or impedance.

If you can, you can use a simple splitter.

3

He’s not splitting, he’s combining. A mixer is what’s needed.

4

Yeah, but if the outputs are just normal headphone level, you can just mash them all together with a splitter adaptor; this might cause some unattractive destructive interference effects when there is a signal on both inputs, but it isn’t likely to kill anything.

5

This is a decidedly low-tech suggestion, but why not just use simple earphones. One from the MP3 player in one ear, one from the walkie talkie in the other.

6

I was actually considering rigging up a splitter to mix them, but thought I’d heard somewhere that doing that was a kind of bad idear. Considering that 99% of the time the radio outputs, the music player is going to be outputting as well, I’m afraid to do it. “Isn’t likely to kill anything” isn’t very comforting when on one end you have a $100+ music player, and on the other end you have something that’s owned by your work, neither of which you really want to have to replace.

Now, if someone were to come along and tell me it’s nothing to worry about (or that I would only damage my earphones, which I could cheaply replace), then I’d probably go for it.

7

Nothing to add of substance.

Just wanted to say that I worked as a projectionist in the early 90’s and it was probably the coolest job I ever had. Glad to see a fellow projectionist on the board :cool:.

8

Heh, yeah, I actually just started this week after a weekend crash course. I’ve been working at the theater for several months now, and I’m definitely liking the projectionist thing alot better.

9

If you merely mix them you will get a garbled noise when they try to alk to you by interphone. This is okay, you can just switch off the music and ask them to repeat.

To relieve boredom have your girl come to the booth. That’s what I did.

10

Asking them to repeat wouldn’t work since not every call would be for me.

And sadly the latter suggestion is almost completely out of the question, as only projection and some management is allowed in the booth.

11

If the PA system goes all over you would have to have a complete system wiring diagram to figure out a way to keep your music out of other peoples PA stations.

12

Here’s a solution that doesn’t involve tapping into the walkie-talkie system at all.

Go out and buy a set of computer speakers. You can plug your iPod into the speakers and listen without earphones, and at the same time hear what’s happening on the walkie-talkie.