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A Potential MS Problem

Subject: A Potential MS Problem
From: Charles Bragg <>
Date: Tue, 20 Apr 2004 11:24:53 -0700
        Since there has been so much discussion of this technique, I thought 
the following would interest everyone. The URL is 
http://www.locationsound.com/proaudio/ls/tips/techtips8_7.html
        I apologize in advance if this is just noise - I am definitely not a 
microphone expert.

        -- Chuck

=====
COINCIDENT OR "INTENSITY" STEREO TECHNIQUES COMPARED

Stereo recording for television in the U.S. has a potentially nasty pitfall 
waiting for the unwary. The MTS format in the NTSC TV signal is not always mono 
compatible. If non-coincident stereo recordings are used, they will cancel when 
received in a mono TV set. The primary coincident techniques are XY, MS, and 
Blumlein.

XY Cardioids and Hypercardioids:
XY uses a crossed pair of cardioids or hypercardioids. The cardioids are placed 
at an angle of 90-120 degrees and placed fairly close to the sound source. The 
angle for hypercardioids is typically more narrow to preserve a solid center 
image. The increased reach of the hypercardioids allows for a more distant 
placement.

With any stereo technique, the microphones should have as good a polar response 
as possible and be closely matched in all aspects.

MS Stereo:
This intensity technique used a cardioid (the M or mid-component) pointed at 
the source and a figure eight (the S or side-component) oriented laterally. The 
outputs are combined in a sum and a difference matrix which converts the 
signals to XY stereo [(M+S) and (M-S)]. The MS technique provides one major 
advantage in that the ratio of the M and S signals can be changed in the matrix 
to control the width of the stereo image. The only disadvantage is that the MS 
signal is confusing to listen to while monitoring. Many modern mixers and 
recorders have matrix decoders in the monitor circuits to overcome this problem.
=====

========
Chuck Bragg, Pacific Palisades, CA
Membership Chair
Newsletter Editor
Santa Monica Bay Audubon Society:
www.smbas.org 
========



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"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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