How to connect a stereo monitor to a mono signal?


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Not really about recording, but I suspect the panel here might have the answer...

Background: last night's gig was LOUD! I'm a fiddler and couldn't hear myself play, which is a bit of a problem with a fretless instrument! So I'm investigating a way around this for the next time and thought of using in-ear monitor to give me some personal foldback and also to reduce the sound level from the PA, backline amps, etc. My plan is to split the output from my instrument preamp to feed both the mixing desk and my monitor. However, my proposed monitor system has a 1/4" stereo jack input and my preamp is mono.

Hence the question: Am I OK to connect the tip of the mono plug to both the tip and ring of the stereo plug? Gut feeling says, "Yes", but it wouldn't be the first time the obvious answer wasn't correct!

Thanks, Geoff
Thanks chaps. Unfortunately, I'm in UK and couldn't find the items you suggested. However, I did find alternatives by searching for "TS" and "TRS" rather than "mono" and "stereo".

That said, I'd prefer to make up my own cable. I can connect two lengths of low-noise coax to a mono plug and the other end of one cable to an inline mono socket and the other cable to a stereo plug provided the answer to my original question is "Yes"; i.e. it's OK to connect the tip (coax inner) to both the tip and ring of the stereo plug.

Thanks again, Geoff
Absolutely make your own if you can solder. Adaptors can be good, but many are nasty things and they let you down by making them from cheap metal that crackles and then of course, they fall out. Wiring needs to be simple. However - what you want is available off the shelf. Buy a DI box. I'm assuming your fiddle has the usual pickup - a very high impedance if it's piezo, or a lower one if it has an acoustic pickup. (This won't work if it has a mic on it). Stick that into a DI box, which gives the mixer a low impedance mic level feed - which they will like, and the link output is on a quarter inch jack, Tip/sleeve. Make up a cable with a two circuit guitar type jack on one end, and a 3 circuit jack on the other end - wired as you said tip and ring linked together and the screen to the sleeve. No adaptors, nothing to come loose like inline connectors - they are the worst!

Your stereo monitor will function exactly as if you plugged in direct, and the PA people get a mic level feed, not a instrument level one. Jack to jack to the DI, XLR out to the mixer, and your mono to stereo new cable to the monitor system. Job done!
...provided the answer to my original question is "Yes"; i.e. it's OK to connect the tip (coax inner) to both the tip and ring of the stereo plug.
The answer is "yes" for sure no problem. I'm very sorry it took so long for you to get a straight answer. I'm not sure how many of the "engineers" around here know which end of a soldering iron to hold onto, though.

This would not be ideal if you were going the other way. Mixing signals usually wants more than straight wire. Splitting low-Z line level signals (like from your preamp) usually works fine though.
I would connect both left and right together at the tip, and the ground at the ground part (could also be with small ring).
WTF are you talking about? Your picture shows exactly the same thing we've been discussing. T on the "mono" end goes to T AND R on the "stereo" end and the Ss are connected to each other. This is the best and easiest way to split the signal. It matters not one bit which end that connection is made. You could use 2 wire + shield cable, with both inner wires connected to the T on the TS side, but it's kind of a waste when you could use normal 1wire plus shield and jumper at the TRS end.
[MENTION=199612]alterman[/MENTION]: Thanks for the additional input. However, the stereo plug will always be plugged into a stereo socket and the mono plug will always be plugged into a mono socket. My proposed wiring is shown in the attached image:
Surely, if I connect the plugs as you suggest I will only be feeding the left channel of the monitor and so will only get foldback in my left ear?

That said, I might just add a project case with RCA sockets and use 1/4" jack to RCA mono and 1/4" stereo to 2 x RCA mono Y cable to connect the project case to both the monitor and my preamp; and thus avoid any possiblity of shorting.
I mentioned the DI for a very good reason. The mixer gets a balanced, correct level signal, on an XLR, but I assume you are going into the mixer's line level input and are happy doing this - for stage length cables it doesn't really matter that much - but a DI does give isolation - which your split doesn't. The only thing wrong with your proposal is that at some point two cables need connecting to a connector that is full with one - so this either means thinner cable, or a bigger connector. Hence the elegance of the DI.