Turtlerock Forum

I am currently looking into building a Speaker selector box for a friend, it is all line signal that will have two stereo outs and i need to do a summation to Mono. Am wondering weather to use relays with a low level current or just high quality Switches? also wondering what the best way to sum to Mono from a stereo signal? any help would be great.

Hi Ian

Please confirm:

One stereo in
Two stereo out
One mono out
3 way selector directs signal to out 1, out 2 or mono?

Or do you want any of the out permanently on?

Not hard to do at all, once we know exactly what you're after.

Hi Chris,
1x balanced stereo in
2x balanced stereo out
1x balanced mono out.

none on permanently, only one selected at a time.

You'll need:

1 x 4 pole 3 position rotary switch (Jaycar SR1216)
4 x 2k resistors (1/2w 1%) (Jaycar RR0570)
Input/Output connectors (XLR or TRS)
hookup wire, a knob for the rotary switch and a box to put it all in.



The rotary switch has 4 pins in the middle (A, B, C & D) and 12 pins (1 to 12 anticlockwise) around the outside. It has 3 positions:
In the first, A connects to 1, B to 4, C to 7 and D to 10
In the 2nd, A connects to 2, B to 5, C to 8 and D to 11
You can work out the third!

SO, for each balanced stereo in and out there are four wires, yes? L+, L-, R+ and R-.

In L+ goes to A
In L- goes to B
In R+ goes to C
In R- goes to D

Stereo OutA L+ to 1
Stereo OutA L- to 4
Stereo OutA R+ - to 7
Stereo OutA R+ - to 10

Stereo OutB L+ to 2
Stereo OutB L- to 5
Stereo OutB R+ - to 8
Stereo OutB R+ - to 11

Now for the mono sum:


Connect the chassis to the ground (eg S of TRS, or XLR pin 1) of In L and leave all the others unconnected.

Good luck!

Thank you very much