Audio mixing : crosstalk calculation
Can someone give detailed steps to compute crosstalk for this example?


It's quite simple. If signal A has an output impedance of 47 ohms and is passively mixed with a signal B using two 500 ohm resistors then signal B impregnates signal A because there is a simple potential divider.







simulate this circuit &ndash; Schematic created using CircuitLab

If signal A is zero volts (to take the simple case) and signal B is 1 volt, then the voltage appearing at signal A (after the 47 ohm resistor) is: -

1 volt x 47/1047 = 44.9 mV.

This 44.9 mV shouldn't be there ideally i.e. it is cross contamination and, if you worked out what this factor is in decibels then that comes to -26.96 dB.

The way to overcome this is not to bodge-mix by using a passive resistor network but to use a virtual earth summing amplifier.