Help with summing mixer for pedal board

[wirehair]

Hello
I need help making a summing mixer for my pedal board to sum 2 line level outputs (a juno 60 and a spd-sx drum pad running keyboard loops) into my pedal board. It will be mono and be 3 in 1 out so I can add an extra keyboard in the future if I need to. As I understand it I just tie all the tips together each through their own resistor and then tie all of the grounds together.  Is this right? how do I determine what size resistors I should use?  I see some designs have a shunt resistor. Do I need a shunt resistor? If I do how do I determine the size?

Thanks for the help.

[PRR]

Welcome.

Try three 10K resistors Y-ed together.

If the output is too strong for the pedalboard (synths can be much stronger than guitars), try adding 3K 2K or 1K from common to ground.

[wirehair]

10K worked Great!!!

Thank you PRR!