This box operate with 18v but i think can work with less voltage.
I create this to use with YAHAMA EMX5000 PA system to try a simple recording.
XLR is the balance output to be connect with XLR socket.
The square pad is the first pin, middle being the pin 2 and the last round pad is the pin 3.
SPK/LINE is the selector to switch LINE output or SPEAKER output.
Can be modded to operate in PHANTOM power mode.