Originally Posted by Avro_Arrow
The answer above is what happens when you are walking by the computer, see a message you want to answer
and start typing without fully engaging the brain...
I know the feeling too well. Looking back at my post, I cannot find the rationale to put the "a" points where they are
An amplifier is just a device the controls the amount of voltage/current that flows from the power supply rails,
through your headphones and back to the power supply zero volt point. There is no real reason why the headphone
ground needs to return to the amplifier at all when it's real destination is the power supply.
Ok, we agree on the overall understanding. But shouldn't we add the aim to keep wires carrying a current and its return close-by ? A second aim would be to avoid mixing wires with load return, signal ground and decoupling ground. It would seem to bring us to this scheme:
- Input/feedback ground goes to the PS by its own wire
- The return wire follows the output lead and then the supply wires.
- Decoupling caps have a dedicated return to the PS.
I'm lazy and didn't draw the wiring of the second board... because it bring us back to the original question: one or two return wire ? If one, we cannot keep all loops as close as they are.
But I might be too influenced by speakers amp design, where currents are much higher and loops control matter more.