[2178] Passive Mixer

Date: December 29th, 2016 | Comments : [3] | Categories: DIY.

Passive mixer schematic

In many applications, A simple passive mixer can be used to combine signals. The resistors R1 – R4 are used to reduce interaction of the signals but they do not completely eliminate it. The values may be adjusted higher for more isolation; try 100k for the resistors.

If you add a pot after the input jack of each channel, the volume of the signals in the mix can be easily controlled. Here is the schematic for the DOD 240 mixer that uses this technique.
DOD 240 mixer schematic


3 Responses to “Passive Mixer”

[773868] Terry Says: 9:07 pm, January 2nd, 2017

Would it improve the isolation if you placed a diode before each of the 45k resistors?

[773882] Bill H. Says: 10:42 am, January 3rd, 2017

Would this work to couple a headphone out to the line level input of my Tascam recorder?

[773901] Howie Says: 9:12 am, January 4th, 2017

The diode won’t begin to conduct the signal until its forward voltage is reached; you’d end up with a weird, nasty distortion sound as the diode only passes the peaks of the signal and cuts off any signal level below the forward voltage. It would be like a noise gate, of sorts, though you’d be cutting off a lot of good signal instead of just noise.


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