Yamaha PM4000 Operating Manual page 117

moment the choir is called upon, thus reducing noise,
the "hollow" sound from those open mics, and removing
the extra stress on the choir members of having to keep
absolutely still during the entire service. These are but
a few of the ways that the PM4000's ability to mute
overlapping groups of input channels can be used to
advantage.
NOTE: While a similar function could be achieved by
using the Group ON/off switches, the functions are
really different. Consider that the MUTE MASTER
switch kills all the output of the channels, including the
direct-to-stereo bus feed and the aux sends, whereas each
Group ON/off switch kills only one group output. Also,
consider that some input channels feeding a given group
can be killed with one MUTE MASTER, while other
input channels may continue feeding that group output.
Thus, the mute function is distinctly different than the
Group or Stereo output ON/off switches.
Figure 7-4. Block Diagram of the PM4000 Master Mute System
Things can become more complex when an input
channel is assigned to more than one MUTE MASTER
switch. In this case, the mere act of releasing one
MUTE MASTER may not turn on the channel... if the
channel is still being muted by so much as one other
assigned MUTE MASTER. Should the need arise to
turn on a particular input channel without unmuting
other channels, and you don't want to disturb the
previously assigned MUTE switches, you can override
the entire muting system by engaging that channel's
MUTE SAFE switch [24]. MUTE SAFE, in effect, blocks
any of the channel's MUTE ASSIGN switches [22] so
that the channel will be on so long as its ON/off switch
[21] is engaged.
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