
Fit all parts to pcb except one marked zener.
*10R are 10R if powering with 36vdc and have 18v zeners fitted to the PCB. Or if using any +/-12v to +/-18v with no 18v zeners fitted.
BOM for Talkback Comp at this link https://jlmaudio.com/TalkbackComp/BOM%20Talkback%20Comp%20170505.pdf
Use step by step build map at this link https://jlmaudio.com/builds/maps/talkbackcompmap.html
Either link zener with wire or short wires in threshold connector together to enable comp.
Turn both trim pots fully counterclockwise.
Power up with +/-18vdc
Send in 1k tone of -10dBu or less into input XLR so comp is not compressing at all.
Adjust VR2 clockwise until you drop the signal at the XLR output of the comp by 1dB.
Done.
You can now set RV1 for whatever mic gain you need.
The jumper beside the output XLR can be set for 18v phantom power or none.
Enjoy.
JLM STBUS 10pin output (Same as on AMP HEAD, Stereo IO kit etc)
Pin 1 Left +
Pin2 Left -
Pin 3 & 4 V+
Pin 5 & 6 0v
Pin 7 & 8 V-
Pin 9 Right -
Pin 10 Right +
Comp is mono so Left and Right BALIO & XLR Out are all linked together.
To stop crosstalk when talkback not being used Out + & - signals are shorted togehter by relay and comp locked fully down by relay.
Pressing Talkback button removes short on comp and output.



