Stefan Kiessling – organist
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MMS-Stereo Welcome to MMS-Stereo Calculations


Performance, recording, calculation, programming by Stefan Kießling, April-May 2021
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Joseph Nicolas Pancras Royer (1703–1755): La Marches des Scythes. For harpsichord.

A MS (Mid-Side)-microphone setup creates, when properly mixed, two virtual microphones in an XY-configuration, that create a stereo sound (intensity stereo). The mix of the MS-microphones influences the angle and the pattern of the virtual microphones, and as a result also the volume distribution over the stereo image.. As for the standard MS-setup with one mid-microphone and one side-microphone recording angle and pattern/volume distribution are not independent. This can be overcome by using two microphones for the mid (in the best case, a front-facing figure-8 microphone and an omnidirectional microphone or wide-cardioid).

Adjust recording angle, pattern of the virtual microphones here. The stereo image is characterized by its width and also its power sum graph, that shows, how equally loud the sound, coming from different angles, is captured. Some configurations will emphasize or attenuate the center. You can directly adjust this emphasis and the calculator will then determine the appropriate pattern of the virtual mics. Adjusting the recording angle will then either keep the pattern or the center emphasis (as long as this is possible). Not every combination of values is physically possible.

Boost/attenuate center 0.0 dB
XY90 and XY120 stand for cardioid mics with an angle of 90 resp. 120 degrees between their axes (not the recording angle). These two configurations are widely used by common handheld recorders and also tend to be first choice for XY-mic-setups, although 90 and 120 degrees are not a “law”. K1 and K2 are two configurations I personally enjoy. Blumlein (named after Alan Blumlein, inventor of the stereophonic recording technique) makes use of the two fig. of 8-mics only and angles them by ±45 degrees.

Mid-Pattern 1 Sensitivity: mV/Pa Resulting gain
Mid-Pattern 2 Sensitivity: mV/Pa Resulting gain
Side-PatternFig. of 8Sensitivity: mV/Pa Resulting gain

Resulting Polarpatterns

Mixing those three microphones results into a stereo sound that would be achieved with two coincident (=placed as close a possible) microphones of the angle and polar pattern shown here.

Resulting Stereo Image

(L and R are the loudspeakers. The little vertical lines represent a sound source coming from a certain angle. Their horizontal position reflects, where between the two speakers the human brain will think it comes from.) The curve shows the power sum. A flat curve indicates, that sound from all directions within the recording angle is perceived with the same strength. If the curve is going up in the middle, sound from the center is to be heard louder.

360˚ Power sum

The polar graph shows the power sum again, this time for all directions. At 12o'clock is the front, 6o'clock is the back, 3 and 9 are the sides. The closer the curve is to the center, the softer the sound is in that direction. A perfect circle means: sound from all directions is captured with equal intensity.


Fig. of 8 microphone capsule for mid and side: Schoeps MK 8 Wide cardioid microphone capsule for mid: Schoeps MK 21 Microphone amplifier for the capsules: Schoeps CMC 1U Omni microphone (capsule incl. amplifier) for mid: Sennheiser MKH 8020 plastic clips to clip two microphone bodies together: Rycote MS Stereo Clip Field recorder, suitable for on-location recording, with 6 channels: Zoom F6

Cheaper options:

Røde NT5 for mid Omni capsule for the NT5: Røde NT45-O Fig. of 8 microphone: t.bone SC 1100 for mid and side Field recorder with 4 microphone inputs: Zoom H6

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