I've just learned about balanced and unbalanced audio connections and so I started trying to figure out which pieces of my equipment have what.
My Roland U-220 sound module appears to have unbalanced outputs (based on reading the schematic). I have a Behringer UMC404HD (sort of a mixer with a computer interface) with balanced inputs and outputs. Finally, I have two TOA TD-1 amp/speakers with unbalanced inputs (except a single balanced MIC input).
I can connect the U-220 to the UMC404HD and then connect the UMC404HD to the speakers using TS cables and the sound comes out fine (OK, I'm not a nitpicky sound engineer and I'll admit my standards might not be high).
Can someone work me through the signal path to explain why I actually get sound out of the speakers?
For example, the U-220 outputs are T and S. On the UMC404HD, T -> T, S -> R & S. I'm guessing that since S is the ground voltage (is that right?), the UMC interprets R as a 0v signal, inverts it and sums it with T. The net result is that T is unchanged, although with less volume that if the setup were balanced at both ends.
From the UMC4040HD to the speakers, it's less clear. I assume the UMC outputs the audio to T and inverted audio to S. But because I'm using a TS cable, the inverted signal shorts to ground. So T -> T, R & S -> S. I'm totally guessing that shorting R & S delivers a signal that is equivalent to just S. The speaker receives the audio signal and ground, which is just what it wants.
Various articles on the web which discuss building adapter cables and adding resistors suggest that the situation is a bit more complex.