Hi, jazzunit. On the MTX 191, the switches are labeled on the assumption that you'd be using the Neumann stereo shotgun microphone (originally called the RSM 190, now called the RSM 191 by association with this matrix box--the only difference between the two models). Since that's a coincident stereo microphone, the switch settings are "XY" and "MS."
(The Neumann stereo shotgun actually has three capsules--a central, forward-facing supercardioid with the interference tube in front of it for the "M" channel, plus a pair of cardioids facing to the left and right, connected so that the one on the right subtracts its output from the one on the left, thus synthesizing a figure-8 for the "S" channel.)
If you're using the special adapter cable and two active capsules from the KM 100 series, you can space the capsules apart, and then all you need is to pass the signals through the MTX 191 without dematrixing. It looks to me from the block diagram (attached) as if you'd want to set the switch to "MS" for that, and that also makes sense since the two signals coming from the stereo shotgun would be unmatrixed M and S signals.
Incidentally, I used to own an RSM 190. It was a very good-sounding microphone, but not as highly directional as some people seem to expect or imagine. But I've noticed that people who aren't really familiar with shotgun microphones nearly always imagine them doing what no microphone can ever do: give a recording a nice balance of direct and reflected sound, when the sound sources are so far away that the direct sound at the microphone position is swamped by reflected sound.
--best regards
Topic: Neumann MTX-191A (Read 6157 times)