Mono signal copied into both stereo buffers causes cancellation?

nickcamillo

I've been recording mono guitar signals and apparently outputting just one side to the output buffers this whole time. I tried to duplicate the mono signal onto both output buffers and it results in an extremely quiet signal, only audible if you really crank up the volume. I assume this has something to do with phase cancellation. Is there a better way to do this? Do I need to invert the signal on the opposite side or something?

for more context, I saved both the stereo with 1 mono channel and stereo with 2 duplicated mono channels as wav files. When I play them back on my computer, the stereo with 2 duplicated mono channels plays back normally and is as you would expect, louder. But when I play it back in the bela it is almost inaudible

giuliomoro

How are you listening to Bela's output? It could be an issue with the wiring of your headphones, especially if they have a TRRS jack.

nickcamillo

it's a 1/8" to 1/4" TRS going into a recording interface and being played back through studio monitors

giuliomoro

right, what is the audio interface you are connecting it to? What input are you using?

nickcamillo

giuliomoro It's connected to input 2 of a scarlett 18i20

giuliomoro

right, so you are going with a TRS into a (mono) balanced input? That would explain the phase cancellation: the two signals on L and R are almost exactly the same. When connecting them into a balanced input, that will treat the two inputs as + and - and will sum one with the opposite of the other, resulting in (almost) a zero sum. If you want to connect it to a soundcard, you should use two separate inputs on the soundcard (or a rarely seen TRS stereo input), using an unbalanced wiring into each.