XLR impedance matching question.

[Carl Klinkenborg]

On the face of it (in my mind...) the answer seems so simple that I feel I might be missing something!
Do input impedances of multiple devices connected in parallel sum in exactly the same manner as simple resistors?
I have a processor of 60ohm output impedance with which I want to drive six identical amplifiers each with 20kohm input impedance, which I reckon to be a 3.3kohm total load. Acceptable?

 

[Rob Timmerman]

Assuming we're talking device input/output impedances and not transmission line impedances, yes, they can be treated like resistors.

Rule of thumb is that the load impedance should be more than 10x the source impedance, so you are fine there. Calculated loss due the voltage divider formed by the source and load impedances is around 2%, or 0.3dB, which is well within typical manufacturing tolerances. Which is another reason to not worry about the load.

 

[Carl Klinkenborg]

Thanks Rob, much appreciated.