Double M/S with DMS-Splitter box

1. Double M/S Set with Splitter
The DMS splitter box is a passive device that simplifies connecting a double M/S microphone array to the phantom-powered inputs of preamplifiers or mixers that contain matrixing circuitry (e.g. 2 × SCHOEPS VMS 5 U). It divides the three signals into five (the center channel plus the front- and rear-facing M/S pairs), and prevents the two microphones which serve dual functions from being powered twice.

Double M/S with M DMS U passive matrix box

2. Double M/S Set with M DMS
The SCHOEPS M DMS matrix is, in all respects, the simplest and most elegant way to obtain surround signals. It is a small, sturdy box with high-quality transformers forming a passive decoder matrix. Microphone signals are converted directly into 5.0 L / R / C / LS / RS surround signals. A second, switchable mode supplies four signals with no center-channel output.
The matrix parameters have been chosen so that the resulting signals correspond to an optimal arrangement (as shown at left) while avoiding unwanted artifacts. Both settings have the following characteristics:

– minimal overlap (crosstalk)
– optimal pickup balance in all directions
– well-balanced 360° localization capability
– optimal constancy of total levels across 360°
– minimal pickup via the rear lobe (< -11 dB)

The matrix settings were determined through extensive practical testing, including ambient recordings, television shows, and theatrical and musical performances. In general the best possible results will be those obtained by using the output signals of the M DMS matrix directly.
Our investigations also considered other ways to optimize the functioning of the double M/S sets in concert halls and other typical settings in which surround recordings must maintain a fundamental front-back distinction. For example, delaying the surround-channel signals can improve the perception of spaciousness and avoid localization errors throughout a wider listening area. As a further measure to improve the spatial impression, the double M/S array can be augmented with more distantly-placed room microphones.
Phantom powering is required on only three of the inputs to which the M DMS is connected.
Note: The coefficients of the M DMS have been set for use with a front-facing Schoeps cardioid microphone. Unfortunately, the supercardioid or shotgun alternatives of the other Double M/S sets would not produce suitable results with this arrangement.
A “Double M/S” VST plug-in for Windows can be obtained by filling in a registration form at www.schoeps.de/dmsplugin.html. This plug-in supports simple, intuitive decoding of the three microphone signals. It is available for RTAS Mac, VST Windows/Mac

You can get the plug-in here.