The “UM930 twin” is essentially the same as the regular UM930 with a separate rear cardioid capsule and two outputs.

The front capsule is fixed cardioid on the first output. Switching the microphone’s directional characteristic to “rear cardioid” allows the operator to create the polar pattern at the mixer using attenuation and polarity reversals on the second output. Selecting any of the other polar patterns creates a set polar pattern using both capsules which comes up on the second output. Now the engineer can instantly compare the difference between front-facing cardioid from output 1 with the polar pattern selected for output 2, either live or after the fact.