I'm building my own Bluetooth audio receiver using a Bluetooth module 2.1 with A2DP, so I can connect the receiver (with internal power) to any set of speakers that has a 3.5mm jack, then play music via any Bluetooth device like iPhone or PC.
I got the Bluetooth module wired up and can now be paired with any A2DP enabled device, the issues is, the Bluetooth module has output connectors for 2 audio channels: Left Positive, Left Negative, Right Positive, and Right Negative, my question is how do I connect the 2 channels to a female 3.5mm jack? do I need something like a summing box (which I don't really understand yet), or is there a simple way to solve this? I hope to keep the entire receiver small.
P.s. I initially thought the two negatives are two ground so I solder them together to the sleeve of the TRS, but then the module won't turn on. Further testing found that whenever the 2 negative touch the Bluetooth would shot-out and shut-off. If I just connect one of the negative then I have sound coming out of both speakers, but then I think there would be no difference between left and right sounds.