|The please-readme-file||SOS MMAD 0.4||SOS_MMAD.htm|
The SOS_MMAD Website project will cover most aspects of Multichannel Microphone Array Design, including eventually arrays for two, three, four, five, six, seven and eight channels. These arrays are or will be designed initially for microphones with 1st order directivity patterns (Hypercardioid, Supercardioid, Cardioid, Hypocardioid and Omnidirectional).
Arrays will also be shown for Surround and Front Sound Stage Coverage with links to "ROOT ARRAYS", "NATURAL ARRAYS" and "STEERED ARRAYS".
I'm afraid that no links are available for the time being to any Natural Arrays, and Root Arrays are only available for 4 and 5 Channel Front Sound Stage Coverage (FSSC) Arrays.
Since publication of the previous releases
of the SOS_MMAD CDROM, the MMAD diagrams have been redrawn
in high definition PDF format, and extended to cover:
'Help' files have been included on the Backtracks and Crosstracks table and can be consulted using the symbol ' ? ' to the link.
The microphone coordinates and orientations, that have been used for most of the diagrams, are contained in papers presented at various AES Conventions :
The present SOS_MMAD Web-site project contains over 11500 Multichannel Microphone Array Designs with different 1st order microphone directivities, and uses HTML driven access covering a range of specific selection criteria as explained in the paper presented at the 24th AES International Conference :
There are still many links / pages / chapters to be completed - be patient!
The measuring of the anglular coverage segments is always a problem. A prototype design of a measuring instrument called 'The Crocodile' was described in the publication 'St Zoom'. A more streamlined version is shown in 'Microphone Support Systems and Accessories' and can be purchased from Michael Williams at firstname.lastname@example.org (price 570€).
Operation of the Web-Ste
For direct access to the Home Page MMAD you should run "SOS_MMAD.htm" or you can access the next page via the "SOS_MMAD" link at the top or bottom of this page
From the "SOS_MMAD.htm" page you can access the wide range of Multichannel Microphone Arrays Designs via the "Microphone Array Design" link and then select the links to either 4 or 5 Channel Microphone Arrays. Surround Sound Arrays are only available in 5 Channel Array designs, however Front Sound Stage Coverage (FSSC) arrays are available in both 4 and 5 Channel configurations. After choosing the Microphone Array Design link on the SOS_MMAD page, there are another 6 stages in choosing the final array design :
It is essential to experiment different segment coverage values until you find the optimum array design or your particular preference. If you have difficulty determining the physical representation of the various segment angles with respect to the actual sound stage, you should build the "Crocodile" optical measurement tool described in either of the books by Michael Williams - "The Stereophonic Zoom" or "Microphone Arrays for Stereo and Multichannel Sound Recording" or purchase the streamled version now avalable from email@example.com
Please note that a Positive Electronic Offset value shown on the microhone array plan requires delay of the specified value to be applied to the Front Triplet set of microphones with respect to the Back Pair of microphones. Negative delay values on the other hand mean that the Back Pair of microphones is delayed by the specified value with respect to the Front Triplet set of microphones. Detailed analysis of the Offset Segment Steering process is contained in AES preprint 4997. This Electronic Offset can be easily introduced on a Computer based recording system such as Pro Tools simply by shifting the respective tracks by the specified offset value (calculated either in the number of samples or directly in mS).
5 Channels Surround Arrays which do not need any form of Electronic Offset have not yet been shown specifically on this release. This information will be found in the tables shown in AES Preprint 5336 « The Quick Reference Guide to Multichannel Microphone Arrays Part 1 : using Cardioid Microphones » by Michael Williams and Guillaume Le Dû
For the time being, this is not a stand alone product, it must be read in conjunction with the previously published AES papers (as shown in the list below). Many of the terms used have been explained in detail in these papers. Terms such as Front Triplet Coverage, Lateral Segment Coverage, Back Pair Coverage, Microphone Position Offset, Electronic Time Offset etc. must be well understood to be able to use the data correctly.
The theorectical background to the two channel microphone array (stereo) and the development to the MMAD process has been presented at various in papers published at Audio Engineering Society Conventions over the past few years :
The author has also published : "Stereophonic Zoom" in English and "Le Couple Variable" in French which explain in detail the theory behind the design of a stereo array, and also gives some guidance for experimentation in recording of different sound sources.
MICROPHONE ARRAYS FOR STEREO AND MULTICHANNEL SOUND RECORDING Vol 1 by Michael Williams was been published by "Il Rostro" in MILAN in 2004. It is planned to publish the second volume sometime in 2008. Volume 1 covers - the loudspeaker configuration and the listening room - the training of the ear - the operational approach to stereo and multichannel sound recording - a tutorial on microphones. This book costs 20€ plus postage and can be purchased from Michael Williams at firstname.lastname@example.org.
The second volume of this book will probably include the SOS_MMAD CDROM with various Powerpoint and HTML based programs to aid in the teaching of the theory behind the process of microphone array design, together with both teacher's story-board notes and student back-up documentation.
The "Crosstrack/Backtrack shortcut" system has been entirely restructured, to allow greater flexibility and better legibility. Backtracking and Crosstracking to any previous stage in the design process is now possible. I hope all links are operational - please excuse me if this is not the case, there are now over 80000 links within the whole MMAD process and this is becoming difficult to completely check!
If you wish to receive a pre-release of the SOS_MMAD and of course future updates, please send your name, address, telephone & fax number and email to email@example.com and I will put you on the mailing list. A nominal charge of 5€ will be made to cover the costs of postage.
I would be interested in hearing about your experience of sound recording using any of the microphone arrays described - please send any remarks to Mike Williams at firstname.lastname@example.org.
Here is the link to the next page - "SOS_MMAD.htm"