Dorrough 10-A, Instruction Manual, Page: 5 / 19

4
L R
L IN R IN
+ - - +
ON
DORROUGH ELECTRONICS USA
WOODLAND HILLS, CA 91364
PAT. PEND.
Input Gain Controls
VR13 (L) and VR14 (R)
Recessed
Power Switch
AC Cord
Meter Connections
Mono
Input
+ - + - - +
Stereo R
Input Stereo L
Input
Fig. 1. Back panel of DORROUGH Loudness Monitor, Model 40-A or
Model 40-B.
Fig. 2. Meter connections for mono and stereo input signals.
For mono use, connect mono input signal to L+ and L- terminals
and turn R Input Gain Control to the full counterclockwise
position.
...Continued from Page 3
In actual practice, a "B" Type meter is generally used as a discrete
monitor to indicate either a left or right channel. However, for Sum and
Difference monitoring, repeat steps 3 and 4 (previous page), and adjust
each input level control for a -6 dB indication on the meter scale for an
individual channel. This action will result in a proper sum of "0" on the
"B" Type meter scale.
NOTE: Different amplitudes and phase angles between the left and right input
signals will produce different algebraic sums. This display is essential in
indicating center channel buildup in some program material and will aid an
operator in making the proper adjustment to program operating level. For mono
signals, use the suggested connections shown in Fig. 2.
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