I have just completed my first ever electronic creation, a pair of headphones. It composes of a TRS stereo jack joined to four leads (left, right and two for common ground) braided nicely along the way to a 1k potentiometer along the two common ground leads. The braid then carries on to the right speaker (connected by the right lead and one of the ground leads), from there two leads (left and the other ground lead) go over the head band to the left speaker.
The gadget works almost perfectly, almost as it has one problem that I cannot fix. When the potentiometer is set to minimum resistance, the sound is perfect and I'm happy. However, trying to decrease the volume using the potentiometer results in only one of the speakers go quiet plus the overall sound quality seems off.
I hypothesized a couple of causes but I have no idea what the actual fault may be. The most likely cause in my opinion is putting the potentiometer on the ground leads instead of connecting a double gang (or maybe double pole single throw(?)) potentiometer to control simultaneously through right and left leads. On the other hand, putting potentiometer on common ground should affect both speakers equally nevertheless.
I don't know what to do so I'm asking the experts to give a helping hand.
EDIT: For those who requested a schematic, I hope I displayed the situation clearly in this one.
The reason for the double ground wire between potentiometer and the TRS plug is just so the braid look uniform plus to hopefully reduce resistance along the wire (increased cross-sectional area).