A time coincident, compact and adjustable surround configuration.
Keywords: Double MS, coincident, adjustable, mid/side, figure-of-eight, bi-directional
Abstract: The double MS setup is a time coincident, compact and adjustable configuration for surround sound / immersive sound. Two cardioids and one figure-of-eight microphones are used. Alternatively, the setup is created from four cardioid microphones. 

The principle of the double MS technique is a forward and backward pointing MS set, sharing the same side microphone. As in a standard MS setup, the side microphone is positioned with the in-phase side pointing left so only three microphones are needed. But in this set-up, processing / mixing is necessary to create the final format. As always with MS set-ups, two different transducer types are applied to provide the mid-information (cardioid microphones) and the side-information (bi-directional microphones). There is the risk of different frequency and phase responses of sound reproduction from the sides or the front.

This is how the channels are obtained:
Center = Midfront
Left = Midfront + S
Right = Midfront – S
Left surround = Midrear + S
Right surround = Midrear – S

The amount of each signal is adjusted for correct spatial distribution, especially regarding the frontal image. Typically, the L/R width is produced a little wider compared to standard MS for two-channel stereo.

The double MS technique can be attained by using four identical – evenly matched – d:dicate™ 4011 Cardioid Microphones angled on the horizontal plane at 0°, 90°, 180° and 270° respectively.

Double MS setup

Mfront = Cardioidfront
S = S’ (Cardioidleft) – S’’ (Cardioidright)
Mrear = Cardioidrear

Suggested Microphones

If you want to try this setup with DPA microphones, we suggest: