Shure SCM810 User Manual page 15

SCM810 Speech Gate for Mixing Console
The SCM810 can be used in conjunction with large mixing consoles to pro-
vide automatic mixing for talk shows, panel discussions, and news shows.
Large consoles have channel insert jacks so that external signal process-
ing devices can be patched into individual channel signal paths. With this
modification the SCM810 can be placed into unbalanced insert jacks, and
the SCM810 used as a high-quality, external, 8-channel speech gate. This
arrangement allows the operator complete control of each channel via the
console's input control strip, while the SCM810 keeps the number of open
microphones to a minimum.
In this operational mode:
1. The Direct Out jack tip is the input from the mixing console, and the
ring is the output to the mixing console.
2. The SCM810 channel inputs, faders and EQ do not function.
3. NOMA does not function, channel Off-Attenuation is infinite.
4. The front-panel channel overload indicators indicate gating and over-
load for each input.
5. The "Local" operating mode provides a non-automatic audio signal at
the output for use in external mixes.
6. If the insert point on the mixing console is pre-fader, the gain trims
should be set such that all microphone levels
MUTE IN Precedence to OVERRIDE IN Precedence
With this modification and when both MUTE IN and OVERRIDE IN logic are
grounded for a channel, the Override mode will take precedence (as sup-
plied, the MUTE IN takes precedence over OVERRIDE IN).
Dead Zone on MUTE IN Defeat
As supplied, MUTE IN is intended for use as a momentary cough button or
privacy function (mute when necessary). However, if the MUTE IN is in-
tended to be used so that the talker must unmute microphones to enable
speech pickup (unmute when needed), this modification is needed. This re-
moves the muted channel from the MaxBus which eliminates "dead zones."
A dead zone is an area in which a microphone picks up a talker through a
muted microphone and other microphones do not activate for that talker.
Change MUTE IN to Inhibit
As supplied, a channel will mute when its MUTE IN terminal is grounded.
The mute function can be changed to "Inhibit" by an internal modification
for each channel. After the modification, a logic "Low" at the MUTE IN ter-
minal prevents that channel from gating on if it is off, but allows it to remain
on if it is already on.
IMPORTANT: To prevent high-frequency oscillation, never connect a
channel's GATE OUT to its own MUTE IN unless the "Inhibit" modification
has been made.
Change OVERRIDE IN to MUTE IN for Use with Filibuster Mode
This modification should only be performed with the Change MUTE IN to
Inhibit modification described above.
Change Off-Attenuation Level
This modification changes the off-attenuation level from -15 dB to a select-
ed value. Select from the following resistor values.
Off-Attenuation Level
10 dB
20 dB
30 dB
are similar.
Resistor Value
18 kΩ
50 kΩ
150 kΩ
15
Procedure: Short jumpers X103, X107, X108 and X906 (in the Master sec-
tion). Remove resistors R1011, R1019, and R1020.
Procedure: Short jumper X114. Remove resistor R1046.
Procedure: Short jumper X115.
Procedure: Short jumper X111.
Procedure: Short jumper X113. Remove resistors R1046 and R1058.
Procedure: Remove resistors R9088 and R9145. Install new resistor at
jumper points X904 and X908.