DRM3 solderpads and hacks



The DRM3 analog drum module has some solderpads that you can use to change some functions on it.

Disable the 1K output resistor

On the bottom side of the PCB there are 4 solder-switches near the jacks.
By soldering a short for any of these solder pads, you can eliminate the 1K output resistor for that jack.
The OP’s used for this module is TL074 that has built in short-circuit protection on the outputs.
Therefore, it is possible to do this hack if you need, but it is still better to leave the 1K resistors in place for extra protection.

  • SJ2 – Out 1
  • SJ4 – Out 2
  • SJ3 – Out 3
  • SJ1 – Out Mix

Mix out break signal

At the bottom of the pcb, you can solder 2 pins (2×1).
When no cable is inserted in the mix out jack, the mix signal is sent to this pin.
You can for example use this together with the pinstrip on a SHMIX mixer, to connect the mix output internally in your case.
If you have multiple DRM3’s and a SHMIX, you will get a clean look with the mix outputs pre-patched internally.
Use female to female DuPont cables to make the internal connections.

  • JP4 – The “break” or “normalize” signal from the mix output
  • GND – Ground pin