Calrec S2 Operator's Manual page 68

S2
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68
5.2 REWIRING & EXCHANGING MODULES
Modules and circuit cards may be removed and plugged in with the console switched on.
It is advisable however to switch off before exchanging the 5 volt stabiliser and the
processor cards in the multitrack section (if fitted).
5.3 STEREO WIDTH
The stereo width circuit may be seen in the CIRCUITS DESCRIPTION section - No. 14
Stereo Processor. It is well known that the width of a stereo image is a function of the
difference component of signal between left & right - usually given the symbol S
and S = L - R
√ 2
The Mono component of a stereo image is M
and M = L + R
√ 2
The stereo width control therefore passes left and right unchanged in the central
detent, produces L + R at each output in the MONO position (Same level as L or R
2
alone) and produces 2L - R at the left output and 2R - L at the right output in the "WIDE"
position with corresponding variable states in-between.
2L - R & 2R - L represent a considerable increase in the " S " component (width) ie.
S = (2L - R) - (2R - L)
√ 2
= 3L - 3R
√ 2
= 3 (L - R) (ie. X 2.12)
√ 2
5.4 M/S WORKING
From the above it can be seen that it is possible to carry Left & Right information in the
form M and S (Sum & Difference).
This technique has been exploited in many areas of the audio industry over the years such
as stereo microphone design using one ommi (M) receiver and one gradient (S) receiver
and then matrixing the M & S signals to produce left & right as follows:-
Left = M + S
√ 2
Right = M - S
√ 2
(These formulae are compatible in reverse as follows:-