These type of connectors are made by a variety of manufacturers. We use standard IEC connectors for the AC power. This allows use of your synthesizer in almost any country with the correct power cord. They can be purchased at Mouser Electronics or Digi-Key . We use these connectors strictly for DC power supply connections.
Modules have the male PCB mount, and the cabinet's cable harness has the female.
We use these for jacks, push buttons, LEDs and other devices requiring only 2 pins. We use these for potentiomenters, switches and other devices requiring 3 pins. DPDT switches will use 2 of these. For safety and simplicity we don't use this type of connector anywhere else. We use these strictly for connection between the power supply and the DC Cable Harness to carry the DC voltages.