Ambisonic B-Format

Ambisonics is a series of recording and replay techniques using multichannel mixing technology that can be used live or in the studio. By encoding and decoding sound information on a number of channels, a 2-dimensional ("planar", or horizontal-only) or 3-dimensional ("periphonic, or full-sphere) sound field can be presented.

http://en.wikipedia.org/wiki/Ambisonics

Sounds in Ambisonic are provided as interleaved 4 channels audio files, with a layout as this : Channel 1 : W - Channel 2 : X - Channel 3 : Y - Channel 4 : Z

Double-M/S

”Double M/S” is an improved version of the well-known M/S stereo recording technique. In addition to a frontfacing cardioid or supercardioid ”mid” microphone and a figure-8 ”side” microphone, a rear-facing directional microphone is set up.
The front- and rear-facing microphones share the signal of the figure-8 microphone so as to form two complete, back-to-back M/S systems. One M/S system then provides the three front channels (the center channel signal being provided directly by the mid microphone of the front system), while the other system provides the two surround channels. An arrangement of this kind allows flexible processing of the stereo surround image width and post-production adjustment for both of the M/S pairs.

http://www.schoeps.de/en/products/categories/doublems

Sounds in Double-M/S are provided as interleaved 3 channels audio files, with a layout as this : Channel 1 : M1 font - Channel 2 : S - Channel 3 : M2 rear.

IRT

The IRT microphone cross is an arrangement for ambient recording. Its primary characteristic is a transparent and spacious rendering of the acoustic environment.

http://www.schoeps.de/en/products/categories/irt-cross

Sounds in IRT are provided as splitted 4 channels audio files, with a layout as this : Channel 1 : L - Channel 2 : R - Channel 3 : Ls - Channel 4 : Rs.

ORTF Surround

The “ORTF Surround” recording method is a new system for the pickup of surround ambience. This microphone arrangement and its sonic characteristics are quite similar to those of the well-known “IRT Cross“ designed by Günther Theile.

http://schoeps.de/en/products/categories/ORTF-Surround

Sounds in ORTF Surround are provided as splitted 4 channels audio files, with a layout as this : Channel 1 : L - Channel 2 : R - Channel 3 : Ls - Channel 4 : Rs.

OCT Surround

OCT Surround (Optimized Cardioid Triangle Surround) is a five-channel recording method devised by Dr. Günther Theile, which does not use matrixing. 
In this approach, directional microphones are set apart at moderate distances (up to 1 meter), giving good separation between the front sectors L/C and R/C. It also offers good localization, a large listening area and a natural-sounding overall impression.

http://www.schoeps.de/en/products/categories/OCT-Surround

Sounds in OCT Surround are provided as splitted 5 channel audio files, with a layout as this : Channel 1 : L - Channel 2 : R - Channel 3 : C - Channel 4 : Ls - Channel 5 : Rs.

Double A/B

Double X/Y

M/S-A/B aka AmbiTionic (homemade by Yves Capus)

Made on the field for the field . That's the beginning of this system minding.

Why a surround system? Because the larger demand from sound editors and documentary directors, about space and large atmo, relative to unicity of places and sets. More, the interest to make some sound archives about fields , not only like a sound picture but like a real sound landscape, with a 3D impressive feeling.

Why this particular process? Many reasons of course,
The first one , i needed for the less expensive system as possible so i did thank to use the most part of my own previous gears and fit it for the surround purpose. The heart of this system is the Ms Neumann (km120-150) cause i'm very close from this system and all suspension and windjammer already exist, and this apparatus is very easy to custom. By personal taste i like DeltaT process, and i am disappointing by only DeltaI surround system, so i build a system with some DeltaI and DeltaT process.. DeltaI for the front and center information provided by MS system and DeltaT for Ls-Rs source provided by A-B system. Each of this process is included into the same Rycotte MsSystem.
The AB process is provided by 2 Sennheiser me104. These microphones are lightweight , and with a very close sensitivity with the Neumann km120-150, and las but not least, not too expensive. At this time, i can use on the field this system, almost like i did use the simple ms Neumann one.
The 4 channels (M-S-Ls-Rs) are recorder on my Nagra 6, and later process and decode in Protools, with appropriate gain and filtering.
Evermore , i have, in one system, the ability to use the Ms system only, The AB system only or even easily convert this system for DoubleMs purpose …not so bad…
Last but not least, this surround process provide a very good sound like Neumann and Sennheiser can provide.

Why "Ambitionic" ? Cause i looked for the system Ambisonic from Soundfield company, i appreciate the space provided by this system but i do not appreciate the sound, and more i did not sufficient money for buy it... so i called my system "AmbiTionic" cause i did some AmbiTions about Ambisonic!