# How can I output balanced audio from my headphone jack?

I use my laptop to connect to mixers at different venues often. Some of them have inputs for unbalanced lines (like headphones) some do not.

An aside on what a balanced line is: A balanced line is one where a single channel has been inverted. Outputting a balanced signal involves nothing more than multiplying one of the channels (L or R) by -1. It is not "centered," and has nothing to do with panning. More info here: https://www.youtube.com/watch?v=UQPJYWA5Y-o

Some, but not all, audio software allows the user to do this. I'd like to have a system wide solution. Does anyone know a tool or setting for outputting balanced signals from the headphone jack?

EDIT: When a stereo signal gets to the mixer, one channel is inverted and then both are added. This creates a mono output. The signal could be made mono beforehand as well. It's the difference between `(A + B) * -1 * -1` and `(A * -1 * -1) + B`

• Off topic, but: that's a really interesting video. When you say "Some mixers do not have inputs for unbalanced lines", you mean they only have inputs for balanced lines? And surely your headphone socket can only provide a mono balanced signal, not stereo? Commented Feb 18 at 9:29
• "Outputting a balanced signal involves nothing more than multiplying one of the channels (L or R) by -1" False. You cannot turn a stereo signal into a mono balanced signal by inverting the polarity of one of the channels. Also, there’s nothing wrong with plugging an unbalanced signal into a balanced input. What you need is a simple adapter cable that splits the TRS stereo connector into two mono TS connectors. Commented Feb 18 at 16:03
• @ToddWilcox Yes, presumably you would have to e.g. Delete the Right channel, copy the Left channel into it, and then invert that, to get a balanced mono Left channel. Just inverting the Right channel in a stereo pair doesn't make it balanced. Commented Feb 18 at 16:08
• I've added some edits on how stereo goes to mono. @benwiggy Yes, it does go from stereo to mono in this process. Commented Feb 18 at 17:00
• @ToddWilcox plugging an unbalanced line into a balanced input leads to the entire center (ie mono) realm getting canceled out. If the signal going in in mono, you get silence. If it is stereo, you get just the "width," ie the differences between L & R. Typically, all the bass will be gone, instruments will only be as loud as they are panned, and reverb is nearly full loudness. I've unintentionally done this experiment many times, this is what happens. Commented Feb 18 at 17:02