Shure SCM810 User Manual page 2

GENERAL DESCRIPTION AND FEATURES
OPERATING PRINCIPLES
FRONT-PANEL CONTROLS, CONNECTORS, INDICATORS
REAR-PANEL CONTROLS, CONNECTORS, INDICATORS
DIP SWITCHES
SETUP
MOUNTING
CONNECTIONS
CONTROL SETTINGS
LIMITER
EQUALIZER
MIXER LINKING
SPECIFICATIONS
ADVANCED FUNCTIONS
LOGIC CONNECTION SPECIFICATIONS
SUGGESTED LOGIC APPLICATIONS
VOLTAGE SELECTION
INTERNAL MODIFICATIONS
The SCM810 is designed for use in a wide variety of multiple
microphone speech applications. It is an audio processor that
only activates microphones or input channels that are being
addressed. The operational concept behind the SCM810 is
called Shure IntelliMix . It delivers seamless automatic mix-
ing by combining three unique functions: Noise-Adaptive
Threshold, MaxBus , and Last Mic Lock-On .
Noise-Adaptive Threshold distinguishes between constant
background noise (such as air conditioning) and rapidly
changing sound (such as speech) for each input channel. This
function continuously adjusts the activation threshold so that
only speech levels louder than the background sound will acti-
vate an SCM810 channel.
MaxBus eliminates the poor audio quality that results when
a talker is picked up by more than one microphone. It does this
by controlling the number of microphones that may activate for
a single sound source. With MaxBus, one talker will activate
only one SCM810 channel, even if multiple microphones are
"hearing" that talker.
Last Mic Lock-On maintains a seamless audio mix by keep-
ing the most recently activated microphone open until a newly
activated microphone takes its place. Without Last Mic Lock-
On, a long pause in conversation may allow all microphones to
turn off, and it may sound as if the audio signal has been lost.
Last Mic Lock-On ensures that background ambience will al-
ways be present.
The extreme sensitivity of the Intellimix circuitry may allow some channel gating due to static discharge or abnormal electri-
cal disturbance to the power or signal lines. The unit will not be damaged: normal operation will resume after the disturbance
ceases.
TABLE OF CONTENTS
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OPERATING PRINCIPLES
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Multiple miking situations -– with several talkers participat-
ing -– have always presented problems for the audio techni-
cian. If too few mics are used, the coverage of each talker may
vary, with one talker (nearest the mic) being louder and clearer
than the next. Talkers farthest from the mics will sound
"echoey" and reverberant, as very little of their direct sound
reaches the microphones. If too many mics are used, there's
more background noise and reverberation pickup, as well as
less gain before feedback with a sound reinforcement (PA)
system.
It's similar to having multiple video cameras all focused on
the same subject. If these camera signals are combined, the
result is a blurred image. When multiple microphones are open
for a single talker, the result is a blurred audio signal. It's often
not practical for someone to turn mics on when they are need-
ed and off when they are not. The SCM810 automatic micro-
phone mixer solves these problems.
The SCM810 automatically attenuates (turns down) any mi-
crophone not being used, greatly reducing the excess rever-
beration and feedback problems associated with the use of
conventional multiple microphone and mixer techniques.
When a new talker starts to speak, the SCM810 immediately
selects and silently activates the most appropriate micro-
phone. Shure IntelliMix signal processing enables the
SCM810 to provide clear, natural voice pickup. The SCM810
significantly reduces the problems of "hollow" or "muddy"
sound, and insufficient gain before feedback.
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