This symbol indicates that there are important operating and maintenance instructions in the literature accompanying this unit.
WARNING: Voltages in this equipment are hazardous to life. No user-serviceable parts inside. Refer all servicing to qualified service personnel. The safety certifications do not apply when the operating voltage is changed from the factory setting.
WARNING: This product contains a chemical known to the State of California to cause cancer and birth
defects or other reproductive harm.

DESCRIPTION

The Shure Model SCM810/E is an eight-channel automatic microphone mixer designed for use in sound reinforcement, audio recording, and broadcast applications. The SCM810 dramatically improves audio quality in any application where multiple microphones are required. Any low-impedance dynamic or condenser microphone (including wireless) can be used with the SCM810/E. Multiple SCM810 mixers can be linked to other SCM810/E mixers, as well as to Shure Models FP410, SCM410 and SCM800 mixers. Each input channel has a two-band equalizer and three logic terminals. The equalizer reduces unwanted low-frequency audio pickup and makes different microphone types-lavaliers, boundary and handheld-sound similar. The logic terminals can be used to control external devices. The SCM810 operates on 100-120 Vac power; the SCM810E operates on 220-240 Vac power. Each mixer is supplied with a power cord, rack-mounting hardware, and a link cable.

SYSTEM FEATURES

Fast-acting, noise-free microphone selection that automatically adjusts to changes in background room noise Automatic gain adjustment as additional microphones are activated Last Mic Lock-On circuit that maintains ambient sound Adjustable low-frequency rolloff and high-frequency shelving for each channel Channel activation and clipping indicators Peak-responding output limiter with selectable thresholds and LED indicator Active balanced microphone-level XLR inputs and an active balanced Mic/Line level XLR output Aux-level input with manual level control Front-panel headphones output with level control Linking capability for up to 400 microphones

OPERATING PRINCIPLES

The operating concept behind the SCM810/E Automatic Mixer is Shure's patented* IntelliMix circuitry. IntelliMix delivers seamless automatic mixing by combining three separate functions: Noise Adaptive Threshold. Distinguishes between constant background noise (such as air conditioning) and changing sound (such as speech) for each input channel. It continuously adjusts the activation threshold so that only speech levels louder than the background noise activate a channel. MaxBus. Controls the number of channels that may be activated for a single sound source. One talker activates only one channel, even if multiple microphones hear that talker. Last Mic Lock-On. Keeps the most recently activated microphone open until another microphone is activated. Without Last Mic Lock-On, a long pause in conversation would cause all microphones to turn off, which would sound as if the audio signal had been lost. Last Mic Lock-On ensures that background ambience is always present.

FRONT PANEL FEATURES

MODEL SCM810 FRONT PANEL

FIGURE 1

Microphone Channel Gain Controls 1 - 8: Allows adjustment of
microphone gain. Input LED 1 - 8: Lights green when channel is active; lights red at 6 dB below clipping level. Low-Cut Filter 1 - 8: Recessed screwdriver adjustment provides adjustable low-frequency rolloff (high pass) to reduce undesirable low-frequency signals. High-Frequency Shelving Filter 1 - 8: Provides level boost or cut in mid/high-frequency region to compensate for off-axis tone coloration, or for cutting high-frequency sibilance. AUX Level Control: Sets the input level for aux-level equipment connected to the adjacent 1/4-inch INPUT phone jack or rear-panel 1/4-inch AUX input.
Aux INPUT 1/4-inch Phone Jack: Mixes external auxiliary- or
line-level sources into output. This out is not automatic. Signal appears at output of all linked mixers. MASTER Level Control: Determines the overall mix level. Output Level Meter: Nine-segment LED meter indicates peak output signal level. Last LED indicates limiter action. PHONES Control and 1/4-inch Phone Jack: Permits monitoring of mixer output through headphones. The PHONES knob controls headphones output level. POWER LED: Lights green when unit is powered.

REAR PANEL FEATURES

SCM810 REAR PANEL

FIGURE 2

AC Power Connector and Rocker Switch: Connector supplies AC
power to unit when plugged into a power source: the rocker switch turns the unit on.
DIRECT OUT 1/4-inch Phone Jacks: Provides non-gated aux-level
signal from each channel. Direct outs are wired pre-fader and pre-EQ. Can be modified for use as a gated channel output, send/receive insert point, or external speech gate for mixing consoles (see Internal Modifications section).
Microphone Logic: DB-25 male connector interfaces with each
channel's GATE OUT, MUTE IN, and OVERRIDE IN logic terminals. See the Suggested Logic Applications section. NOTE: THIS IS NOT AN RS-232 PORT. mixer (see DIP Switches section).

AUX/D.O./D.O. Switch: Located behind the Line Output connector,
this switch selects either aux input function or direct output function for channel 8 Direct Out jack. Left switch position is AUX IN; center and right positions are DIRECT OUT.
DIP Switch: The 7-position DIP switch provides setup options for the LINK IN/OUT Jacks: Allow multiple mixers to be stacked for additional inputs. Up to 50 SCM810 mixers can be linked.
INPUT 1-8 Removable Block Connectors: Active balanced microphone- or line-level inputs.
LINE OUTPUT Removable Block Connector: Active balanced
line-level signal for connection to amplifiers, recorders or other mixers. Output can be modified to microphone level (see Internal Modifications). 4
Input 1 - 8 MIC/PHM/LINE Switch: Located behind the removable
block connector, this switch selects operation at either microphone-level (left), microphone-level with 48 V phantom power (center), or line-level (right) signals.

DIP SWITCHES

The rear-panel DIP switch provides the following setup options. The positions shown in bold type are the factory settings. NOTE: Switch positions and effects are shown in Figure 3 and also on the mixer label.

(MIXER REAR PANEL)

DIP SWITCH SW702
MODIFIABLE FUNCTION SWITCHES FIGURE 3
DIP SWITCH SW702 FUNCTIONS
Switch Function Switch Position Number Manual/Auto 1 Last Mic Lock-On 2 Hold Time 3 Off-Attenuation Level Up 6 Up 5 Down 6 Up Switch Up Auto On 0.4 second 15 dB 5 Up 6 Down 5 Down 6 Down Switch Down Manual All mics off after hold time 1.0 second Limiter Threshold 5,6 Link Local/Global 7

= Limiter off

= +8 dBm Global = +16 dBm

= +4 dBm Local

(completely off)
Manual/Auto: Automatic activation is defeated in the Manual position. In Manual mode, functions as a standard 8x1 mixer. Last Mic Lock-On: Last Mic Lock-On feature keeps the most recently activated microphone turned on until a newly activated microphone takes its place. When defeated, microphones turn off after their preset hold time. Hold Time: Adjusts the time an activated microphone (which is not locked on) remains on after the talker stops talking. Settings are 0.4 seconds or 1.0 second.
Off-Attenuation: Changes the off-attenuation level from 15 dB to infinity (). With the 15 dB setting, an unused microphone is 15 dB lower in level than when it is activated. With the setting, an unused microphone is completely off. Limiter Threshold: Changes the output limiter threshold. Settings are OFF (factory setting), +16 dBm, +8 dBm, or +4 dBm (see Internal Modifications for other threshold settings). Link Global/Local: Determines whether each linked SCM810 output contains only its own program output, or that of all linked mixers (see Mixer Linking for more information).

+-2 -4 -6 -8 -FULL CCW 50% ROTATION 100 1,000 FREQUENCY (Hz) 5,000 FULL CW
LOW-CUT FILTER EFFECTS FIGURE 6

+10 FULL CW

High-Frequency Shelving
The fixed-frequency equalizer produces a 6 dB boost or cut at 5 kHz and above (see Figure 7). High-frequency shelving is extremely useful for boosting flat frequency response, tempering very sibilant vocal microphones, or enhancing the sound of off-axis lavalier microphones.
+8 +6 +4 +-2 -4 -6 -8 -1,000 FREQUENCY (Hz) 10,000 20,000

50% ROTATE

FULL CCW
HIGH-FREQUENCY SHELVING EFFECTS FIGURE 7
USING AN EQUALIZER/FEEDBACK CONTROLLER WITH AN AUTOMATIC MIXER
When setting up a sound system which has an outboard equalizer or feedback controller in the signal chain, set the SCM810 to MANUAL. This activates all microphone inputs, so every possible feedback path is open. With the SCM810 in MANUAL mode, equalize the sound system and/or Ring Out the room to set the feedback controller. After equalizing the sound system, set the SCM810 to AUTOMATIC mode. Remember that the input of an automatic mixer drops by 3 dB every time the number activated inputs doubles. When using an SCM810 in MANUAL mode, the master output drops by 9 dB when all 8 inputs are activated. Conversely, it will rise by 9 dB when switched back to AUTOMATIC mode.

BASIC MIXER OPERATION

1. Turn on the Power switch. 2. Adjust each channel level so that its Overload LED flickers only during very loud speech or noise. 3. Turn unused channel controls full counterclockwise. 4. Adjust the SCM810 Master level control for the required output level, as indicated by the output peak meter. 5. If a headphone monitor is to be used, adjust the PHONES control knob until the desired volume level is reached.The SCM810/E is now ready to use. NOTE: The SCM810/E mixer is fully automatic. For most applications, no additional adjustments are required.
NETWORKING MULTIPLE MIXERS
If additional inputs are needed, more SCM810 mixers (as many as 50) can be linked using supplied link cables. Such a configuration can provide up to 400 microphone inputs. To link multiple mixers, connect the LINK OUT of the first mixer to the LINK IN of the next mixer, and so on (see Figure 8). Leave the LINK IN jack of the first mixer and the LINK OUT jack of the last mixer unconnected. As long as the link jacks of all mixers are connected (out-to-in, sequentially, leaving one Link In and one Link Out jack unconnected), the automatic mixing functions will be shared by all units. All input signals appear at all linked mixer outputs. There is no master/slave relationship. The output controls and functions of each linked mixer are post-link and do not affect the signals appearing at other linked mixer outputs. Each mixer's Master level control only controls its own output. Each output can be used independently. NOTE: The actual off-attenuation in the 15 dB switch position increases as more mixers are linked. This reduces excessive noise and reverberation contributed by the increased number of attenuated microphones. In a linked system, the Aux input of any mixer appears at each linked mixer's output. See Internal Modifications to defeat the linking of Aux signals. IMPORTANT: When using the logic terminals on linked mixers, connect the LOGIC GROUND terminals of each unit together. Switching clicks may result if this is not done. LINKING MIXERS FIGURE 8

GLOBAL/LOCAL FUNCTIONS

The Global/Local switch selects which input channels appear at that linked mixer's output. Set to the Global position, all input channels appear at that mixer's output. Set to the Local position, only its own eight input channels appear at that mixer's output. The Master level control, in any mode, only controls the level of its own output. The Master level control is independent of the Global/Local switch. The output level of each mixer is affected only by its own Master control. All automatic functions (such as Last Mic Lock-on and MaxBus) are connected on all linked mixers and are not affected by the Global/Local switch. An example of the possibilities of this setup is shown in Figure 9 Here two SCM810s are set to Local, and the resulting sound distribution provides local sound reinforcement while avoiding feedback. This is a simple mix-minus setup. The third SCM810 is set to Global and feeds a tape recorder, At the same time, the automatic functions (Last Mic Lock-On, etc.) remain common to all mixers. The following table summarizes the mixer settings.
SCM810 C (GLOBAL) LINK SCM810 A (LOCAL) SCM810 B (LOCAL)

RECORDER

MIXER A B C
Link Global/ Local Switch Local Local Global
Audio Output Contains. A B A, B, C

LOUDSPEAKER

LINKED SCM810 MIXERS FIGURE 9

LINK CABLES

Additional link cables are available as Shure Part No. 95A1143 (305 mm-12 in.). Longer cables in a variety of lengths are available from Apple Computer as computer printer connections; they are variously referred to by Apple as shielded serial cable with two mini DIN-8 connectors, and Apple System Peripheral-8 Cable. 8

SPECIFICATIONS

Measurement Conditions (unless otherwise specified): Line voltage 120 Vac, 60 Hz (SCM810) or 230 Vac, 50 Hz (SCM810E); full gain; 1 kHz, one channel activated; source impedances: Mic 150 , Line 150 ; terminations: Line 10 k, Phones 300 (tip-sleeve and ring-sleeve), Direct Out 10 k; Auto mode, equalization controls adjusted for flat response Frequency Response (Ref 1 kHz, channel controls centered) 50 Hz to 20 kHz 2 dB; -3 dB corner at 25 Hz Voltage Gain (typical, controls full clockwise) Output Input Low-impedance mic (150 ) Line Aux Send/Return Inputs Impedance Input Mic Line Aux Send/Return Outputs Impedance Output Line Headphones Designed for use with >600 8-200 , 60 recommended >2 k >2 k Actual (typical) Output Clipping Level +18 dBV +12 dBV Designed for use with 19-600 Actual (typical) 1.6 k 10 k 10 k 10 k Input Clipping Level -15 dBV +22 dBV +22 dBV +18 dBV Line 80 dB 40 dB 44 dB 20 dB Headphones 88 dB 48 dB 52 dB 28 dB Direct Out 34 dB -6 dB Input Channel Activation Attack Time 4 ms Hold Time0.4 s (Switchable to 1.0 s) Decay Time0.5 s Off-Attenuation 15 dB (switchable to ) Overload and Shorting Protection Shorting outputs, even for prolonged periods, causes no damage. Microphone inputs are not damaged by signals up to 3 V; Line and Monitor inputs by signals up to 20 V Equalization Low-frequency 6 dB/octave cut, adjustable corner from 25 to 320 Hz High-frequency6 dB at 5 kHz, 8 dB at 10 kHz, shelving Limiter Type Peak Threshold Switchable: off, +4, +8, +16 (dBm at output) Attack Time 2 ms Recovery Time 300 ms Indicator Lights red when limiting occurs Input LEDs Green on channel activation, red at 6 dB below clipping Phantom Power 46 Vdc open-circuit through 6.8 k series resistance per DIN Operating Voltage SCM810: 120 Vac rated nominal, 50/60 Hz, 200 mA SCM810E: 230 Vac rated nominal, 50/60 Hz, 100 mA Temperature Range Operating: 0 to 60 C (32 to 140 F) Storage: -30 to 70 C (-20 to 165 F) Overall Dimensions 44.5 mm H x 483 mm W x 317 mm D (1 3/4 x 19 x 12 1/2 inches) Net Weight 4.3 kg (9 lb 9 oz) Certifications SCM810: Listed by Underwriters Laboratories, Inc.; Certified by Canadian Standards Association; SCM810E: Conforms to European Union Directives; Certified to EN60065; Eligible to bear CE Marking; Conforms to European EMC Directive 2004/108/EC; Meets Harmonized Standards EN55103-1:1996 and EN55103-2:1996 for residential (E1) and light industrial (E2) environments. Authorized European representative: Shure Europe GmbH Headquarters Europe, Middle East & Africa Department: EMEA Approval Wannenacker Str. 28 D-74078 Heilbronn, Germany Phone: +0 Fax: +14 Email: EMEAsupport@shure.de

MUTE 2 MUTE 4 MUTE 6 MUTE 8
Logic controls are accessed at the DB-25 multi-pin connector on the rear panel (Figure 11). The pin connections are given in the following table.
GATE 1 GATE 3 GATE 5 GATE 7 LOGIC MUTE 1 MUTE 3 MUTE 5 MUTE 7 GROUND ORIDE 2 ORIDE 4 ORIDE 6 ORIDE 8
+5 V 10K GATE OUT FROM SCM810 CIRCUIT LOGIC GROUND MUTE IN OR OVERRIDE IN

55K TO SCM810 CIRCUIT

GATE 2 GATE 4 GATE 6 GATE 8 ORIDE 1 ORIDE 3 ORIDE 5 ORIDE 7
LOGIC CONNECTOR FIGURE 11

LOGIC CONNECTIONS

Logic Function Input Channel all Connector Pin No. 13
LOGIC EQUIVALENT CIRCUIT DIAGRAMS FIGURE 10 MUTE IN: Applying logic low (from GATE OUT or a switch closure to logic ground) gates channel off (see Figure 10B). Channel output drops to -. OVERRIDE IN: Applying logic low (from GATE OUT or a switch closure to logic ground) forces channel on (see Figure 10B). Factory setting provides that when both Mute and Override are activated, Mute takes precedence (see Internal Modifications for Override precedence). LOGIC GROUND: Logic ground is distinct from the SCM810 audio ground. Make all logic ground connections to this pin, including power supply ground of external logic circuitry. To avoid switching clicks, do not connect logic ground to audio, chassis or rack grounds.
GATE OUT1 GATE OUT 2 GATE OUT 3 GATE OUT 4 GATE OUT 5 GATE OUT 6 GATE OUT 7 GATE OUT 8 OVERRIDE IN 1 OVERRIDE IN 2 OVERRIDE IN 3 OVERRIDE IN 4 OVERRIDE IN 5 OVERRIDE IN 6 OVERRIDE IN 7 OVERRIDE IN 8 MUTE IN 1 MUTE IN 2 MUTE IN 3 MUTE IN 4 MUTE IN 5 MUTE IN 6 MUTE IN 7 MUTE IN 8 Logic Ground
SUGGESTED LOGIC APPLICATIONS
This section contains suggestions on the uses of the SCM810's logic capabilities. Note that uses of these functions are not limited to the listed applications. The user is limited only by individual imagination and creativity. For additional suggestions and solutions to installation problems, contact Shure's Applications Group. In the following paragraphs, the wiring diagrams refer to the DB-25 connector pins shown in Figure 4.
Remote Channel-On Indicators
Remote indicators can be used to indicate when a talker's microphone is on. Connect the LEDs and a 5-volt supply to the GATE OUT pins as shown in Figure 14 (Channels 1, 2 and 3 shown modified). To avoid switching clicks in the audio output, do not ground the power supply negative terminal in the audio system or rack ground. IMPORTANT: If a single cable is used for the microphone audio signal and the LED dc power, separate shielded pairs must be used. Failure to carry the dc power on a shielded pair may result in audible clicking due to capacitive coupling between the dc power lines and microphone lines.

Cough Button

The talker can turn off his or her microphone during coughing or private conversations by installing an SPST pushbutton switch between the MUTE IN and Logic Ground pins for each channel to be modified (see Figure 12Channels 1, 2 and 3 modified). When a channel is muted, no audio is passed. (See Dead Zone on MUTE IN Defeat in Internal Modifications section for more information on MUTE IN logic.)

5 V POWER SUPPLY

LOGIC GROUND

LOGIC GROUND M1 M3

R = 470

, 1/4 W

REMOTE CHANNEL-ON INDICATORS FIGURE 14 COUGH BUTTONS FIGURE 12
Disabling the Gating Function (Bypass)
To keep certain microphones on at all times, wire the desired microphone channel's OVERRIDE IN pins together to the Logic Ground pin. The selected channels now function as they would in a non-automatic mixer (see Figure 15-Channels 1, 2 and 3 modified).

LOGIC GROUND O2

Chairperson-Controlled Muting
The chairperson can, by activating a switch, silence all other microphones and be heard without interruption. For operation in this mode, connect all the MUTE IN pins together except that of the chairperson's channel, and wire an SPST pushbutton or toggle switch between those MUTE IN and Logic Ground pins (see Figure 13-the chairperson is shown as Channel 1). An alternative to a switch is to connect the chairperson's GATE OUT to the MUTE IN of other channels. When the chairperson's microphone activates, all other microphones mute.

CH. 1 M3 M5 M7

GATING BYPASS FIGURE 15
CHAIRPERSON-CONTROLLED MUTING FIGURE 13
Inhibiting Gating for Unwanted Sounds
As described in the Operating Principles section, MaxBus attempts to activate only one microphone per sound source. Muting a microphone channel prevents its audio from appearing at the mixer's output. However, the muted microphone still communicates with other mic channels via MaxBus. A sound source picked up by a muted microphone will not activate other microphones. Sound sources that may cause unwanted microphone channel activation include: A noisy fax machine or printer A squeaky door A paging system loudspeaker An audio teleconferencing return signal loudspeaker The SCM810 can prevent these and similar sounds from activating microphones by taking the following steps. 1. Place one microphone near the unwanted sound source. Connect that microphone's signal to a channel input, -orconnect the unwanted sound source directly into a Mic/Line channel input. 2. Mute that channel using the logic terminal (see Figure 16-Channel 1 is muted). 3. Adjust that channel's gain control just to the level where other microphones in the system do not activate for the unwanted sound. If the channel gain is set too high, other system microphones will be difficult to activate for desired sounds. If set too low, unwanted sounds will continue to activate other microphones.

12 V POWER SUPPLY

D = 1N4148

Filibuster Mode

In normal operation, when several people talk, each microphone gates on so that no speech is missed. In filibuster action, a microphone that is gated on prevents other microphones from gating on. Once a microphone has gated on, other microphones cannot gate on until the talker has paused long enough for that microphone to gate off. Thus the person talking has the floor and cannot be interrupted. To establish this function, first perform the internal Mute to Inhibit modification (see Internal Modifications). Then connect all the MUTE IN pins of the modified channels together, all the GATE OUT pins of the modified channels together, and the GATE OUT pin of one modified channel to the MUTE IN pin of another modified channel (see Figure 18Channels 1, 2 and 3 modified). Turn the Last Mic Lock-On switch (SW702, position 2) to off. NOTE: To prevent high-frequency oscillation, do not wire a channel's GATE OUT pin to its own MUTE IN pin unless the Mute to Inhibit change has been made.

LOGIC GROUND M1

INHIBITING GATING UNWANTED SOUNDS FIGURE 16

Loudspeaker Muting

Some applications require a loudspeaker to be placed near each talker to provide audio reinforcement, or to permit telephone conversation or conference monitoring. Each loudspeaker can cause feedback unless it is automatically switched off when the talker near it speaks. To provide this function, connect the GATE OUT terminal of each channel to a separate loudspeaker muting relay as shown in Figure 17 (Channels 1, 3 and 5 shown modified). Recommended relays are Omron G6B-1174P-US-DC12, Potter & Brumfield R10-E1Y2-V185, or equivalent (available through Digi-Key and Newark Electronics). NOTE: A diode across each relay coil is required to suppress inductive voltage spikes which may damage the SCM810. An existing sound system using 24-volt relays can be used with the SCM810 without modification if the relay coil current draw is under 500 mA.

JUMPER

Inhibit Function
See Internal Modifications.

LOUDSPEAKER MUTING FIGURE 17

G1 G3 M1 M3 G2 M2

FROM POWER AMP

FILIBUSTER MODE FIGURE 18
Diode Isolation of Logic Controls
Two or more control functions using the same logic pins can be isolated with diodes. In this manner a channel can be muted by an overall group mute switch, or by its own cough button (see Figure 19-Channels 1, 3 and 5 modified).
Mixer logic may be used with 15-volt CMOS logic if a pull-up resistor is used with each GATE output (see Figure 20-Channel 1 modified).

5.1 K 15 V POWER SUPPLY

GROUP MUTE

D = 1N4148 OR EQUIVALENT

CMOS GATES LOGIC GROUND G1 M1

COUGH BUTTONS

DIODE ISOLATION OF LOGIC CONTROLS FIGURE 19

External Logic Devices

SCM810 logic levels are directly compatible with TTL and 5-volt CMOS logic families. For information on logic gate use, refer to the TTL Cookbook and CMOS Cookbook, both by D. Lancaster, Howard Sams Publishing Co.

15-VOLT CMOS FIGURE 20

Digital Controls or Microcomputers
The SCM810 logic pins can interface with custom-designed digital control circuitry or microcomputers for unlimited possibilities of system control functions.

INTERNAL MODIFICATIONS

WARNING: All modifications must be performed by qualified service technicians. NOTE: Remove AC power before opening the unit. This section describes SCM810 modifications that can be made using solder jumpers on the printed circuit board; the pads where jumpers may be used are placed close together so that a single solder drop functions as a jumper. Note too that: 1. The only printed circuit board legends used for these modifications are jumpers (X's) and resistors (R's). 2. Where resistors are to be added, through-holes are present on the board. 3. For individual channel modifications, the first number of the reference designation refers to its channel number, i.e., R1027 refers to a Channel 1 resistor, X7216 refers to a Channel 7 jumper, etc. All references to Channels 1 through 8 in the following paragraphs use Channel 1 jumpers and resistors as reference. Modifications affecting the Master section are preceded by the number 9" (X901, etc.). To gain access to the main printed circuit board, remove the 8 Phillips head screws securing the top cover, and remove the top cover. Most modifications can be made from the top of the main board.
Line-Level Output to Mic-Level Output
Procedure: Short jumper X901. Remove resistors R900 and R909.
Disable Master Level Control
The Master gain control can be disabled so it cannot be tampered with. The table indicates the resistor value to be used for the desired gain. Procedure: Remove resistor R9230. Install new resistor at jumper X914.
Master Section Gain -6 dB dB
Resistance 5.1 k 10 k 20 k

Change Limiter Threshold

All three threshold settings (+16, +8 and +4 dBm) can be changed. To shift the threshold down by 6 dB, resistor R will be 82 k. To shift the limiter thresholds up by 6 dB, R will be 330 k. Procedure: Remove resistors R9177 and R9180. Install new resistor R at jumper X907.

Local Aux Operation

With linked mixers, the Aux input from a modified mixer does not link. Procedure: Remove resistor R9024.

Direct Out to Post-Fader

A channel's Direct Out phone jacks can be changed from pre- to post-fader. Procedure: Short jumper X106. Remove resistor R1011.
Direct Out to Post-Fader Send/Return (Insert)
Changes a channel's 1/4-inch Direct Out jack to a post-fader insert point. Send is tip of phone jack; return is ring. Insert jacks are useful for inserting line-level signal processors into a channel. For instance, a parametric EQ or compressor/limiter can be inserted into a channel for additional processing. Procedure: Short jumpers X101, X102, X105 and X106. Remove resistors R1011 and R1020.
Direct Out to Gated Direct Out
This post-fader, post-EQ channel output is gated, but without NOMA. In this mode, if the Local/Global switch is in Local, a manual mix of channel inputs is present at the Line output. The Off-Attenuation level of the Gated Direct Out signal is infinite. Procedure: Short jumpers X104 and X906 (in Master section). Remove resistor R1011.
SCM810 Speech Gate for Mixing Console
The SCM810 can be used in conjunction with large mixing consoles to provide automatic mixing for talk shows, panel discussions, and news shows. Large consoles have channel insert jacks so that external signal processing 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 overload 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 are similar. Procedure: Short jumpers X103, X107, X108 and X906 (in the Master section). Remove resistors R1011, R1019, and R1020.
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 supplied, the MUTE IN takes precedence over OVERRIDE IN). Procedure: Short jumper X114. Remove resistor R1046.

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 intended to be used so that the talker must unmute microphones to enable speech pickup (unmute when needed), this modification is needed. This removes 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. Procedure: Short jumper X115.
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 terminal 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. Procedure: Short jumper X111.
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. Procedure: Short jumper X113. Remove resistors R1046 and R1058.
Change Off-Attenuation Level
This modification changes the off-attenuation level from -15 dB to a selected value. Select from the following resistor values. Off-Attenuation Level 10 dB 20 dB 30 dB Resistor Value 18 k 50 k 150 k Procedure: Remove resistors R9088 and R9145. Install new resistor at jumper points X904 and X908.

Increase Hold Time

In addition to the dip switch SW702 options of 0.4- and 1.0-second hold time, the hold time can be increased to 1.5 seconds. (More than 1.5 seconds is not recommended.) Procedure: Install a 470 k resistor across jumper points X902. Move DIP switch down to 1.0-second position.

Decrease Hold Time

The hold time can be decreased from the factory preset of 0.4 seconds to 0.3 seconds. (Less than 0.3 seconds is not recommended.) Procedure: Install a 2 M resistor at jumpers X903.
Remote Control of Link Global/Local, Off-Attenuation, Last Mic Lock-on, and Automatic/Manual DIP Switches
If desired, these functions can each be remotely controlled with an SPST switch. Procedure: 1. Solder a wire in the pc board jumper hole adjacent to the desired function (printed on the printed circuit board). These jumpers are located just behind DIP switch SW902. 2. Solder a wire in the pc board jumper hole marked GND near switch SW902. 3. Set the desired DIP switch(es) to the Up position. 4. Run the jumper wires to the desired remote location and solder them to an SPST toggle switch. The wires can exit the SCM810 chassis above the DIP switches. Shorting any wire to the Ground wire will set the function(s) to the corresponding switch down position.

United States: Shure Incorporated 5800 West Touhy Avenue Niles, IL 60714-4608 USA Phone: 847-600-2000 Fax: 847-600-1212 Email: info@shure.com
Europe, Middle East, Africa: Shure Europe GmbH Wannenckestr. 28, 74078 Heilbronn, Germany Phone: 49-7131-72140 Fax: 49-7131-721414 Email: info@shure.de
Asia, Pacific: Shure Asia Limited Unit 301, 3rd Floor Citicorp Centre 18, Whitfield Road Causeway Bay, Hong Kong Phone: 852-2893-4290 Fax: 852-2893-4055 Email: info@shure.com.hk
Canada, Latin America, Caribbean: Shure Incorporated 5800 West Touhy Avenue Niles, IL 60714-4608 USA Phone: 847-600-2000 Fax: 847-600-6446 Email: international@shure.com

www.shure.com

2009 Shure Incorporated

SCM810 Automatic Microphone Mixer Specification Sheet SCM810 EIGHT-CHANNEL AUTOMATIC MICROPHONE MIXER
The Shure Model SCM810 is an automatic microphone mixer using Shure's patented IntelliMix operational concept. Intellimix activates only those microphones being addressed, minimizing the poor audio caused by multiple open microphones. The SCM810 is an eight-channel mixer capa ble of being linked for installations as large as 400 input channels. The single-rack-height chassis is ideal for installations with limited rack space. The removable header-type input and output connectors are quick, convenient, and eliminate the time and expense of wiring XLR microphone connectors.

SYSTEM FEATURES

Reliable, quick-acting, noise-free microphone selection which automatically adjusts to changes in background room noise User-configurable parameters for automatic operation Automatic gain adjustment as additional microphones are activated (NOMA: Number of Open Microphones Attenuator) Last Mic Lock-On circuit maintains ambient sound Adjustable EQ per channel: low-frequency rolloff and highfrequency shelving 48 V phantom power selectable for each input Active balanced microphone- and line-level inputs and linelevel output Highly RF-resistant chassis and circuitry Bi-color LED indication of channel activation and clipping Linking capability for systems up to 400 microphones Non-automatic aux-level inputs with level control Front-panel headphones output with level control Peak-responding output limiter with selectable thresh olds and LED indicator

SPECIFICATIONS

Measurement Conditions (unless otherwise specified): Line voltage 120 Vac, 60 Hz (SCM810) or 230 Vac, 50 Hz (SCM810E); full gain; 1 kHz, one channel activated; source impedances: Mic 150 , Line 150 ; terminations: Line 10 k, Phones 300 tip-sleeve and ring-sleeve), Direct Out 10 k; Auto mode, equalization controls adjusted for flat response

Outputs

Impedance Output Line Headphones Designed for use with >600 8-200 , 60 recommended >2 k >2 k Actual (typical) Output Clipping Level +18 dBV +12 dBV
Frequency Response (Ref 1 kHz, channel controls centered) 50 Hz to 20 kHz 2 dB; -3 dB corner at 25 Hz Voltage Gain (typical, controls full clockwise)
Output Input Line Headphones 88 dB 48 dB 52 dB 28 dB Direct Out 34 dB -6 dB Low-impedance mic 80 dB (150 ) Line Aux Send/Return 40 dB 44 dB 20 dB

Direct Out Send/Return

1 k 1 k

+18 dBV +18 dBV

Total Harmonic Distortion (through 20 Hz20 kHz filter; Input 1 and Master at 5, all other controls full counterclockwise) < 0.1% at +18 dBV output level, 50 Hz to 20 kHz Hum and Noise (150 source; through 400 Hz20 kHz filter) Equivalent Input Noise: 125 dBV Equivalent Input Hum and Noise (150 source; through 20 Hz20 kHz filter) 123 dBV

Inputs

Impedance Input Mic Line Aux Send/Return Designed for use with 19-k 32 k 32 k Actual (typical) 10 k 10 k 10 k 10 k Input Clipping Level -15 dBV +22 dBV +22 dBV +18 dBV
Output Hum and Noise (through 20 Hz20 kHz filter; channel controls full counterclockwise) Master full counterclockwise: 90 dBV Master full clockwise: 70 dBV Common Mode Rejection >70 dB at 1 kHz
TL1031 (Rev. 1) 2009 Shure Incorporated
SCM810 AUTOMATIC MICROPHONE MIXER SPECIFICATION SHEET
Polarity Mic/Line, Send inputs to all outputs are non-inverting; Aux input to all outputs is inverting Input Channel Activation Attack Time: 4 msec Hold Time: 0.4 sec (switchable to 1.0 sec) Decay Time: 0.5 sec Off-Attenuation 15 dB (switchable to ) Overload and Shorting Protection Shorting outputs, even for prolonged periods, causes no dam age. Microphone inputs are not damaged by signals up to 3 V; Line and Monitor inputs by signals up to 20 V Equalization Low-frequency: 6 dB/octave cut, adjustable corner from 25 to 320 Hz High-frequency6 dB at 5 kHz, 8 dB at 10 kHz, shelving Limiter Type: Peak Threshold: Switchable: off, +4, +8, +16 (dBm at output) Attack Time: 2 msec Recovery Time: 300 msec Indicator: Lights red when limiting occurs Input LEDs Green on channel activation, red at 6 dB below clipping Phantom Power 46 Vdc open-circuit through 6.8 k series resistance per DIN Operating Voltage SCM810: 120 Vac rated nominal (see Voltage Selection for 230 Vac operation), 50/60 Hz, 200 mA SCM810E: 230 Vac rated nominal (see Voltage Selection for 120 Vac operation), 50/60 Hz, 200 mA Temperature Range Operating: 0 to 60 C (32 to 140 F ) Storage: 30 to 70 C (22 to 158F) Overall Dimensions 44.5 mm H x 483 mm W x 317 mm D (1 x 19 x 12 in.) Net Weight 4.3 kg (9 lb 9 oz) Certifications SCM810: UL LISTED (U.S.) and cUL Certified (Canada). SCM810E: Conforms to European Union directives, eligible to bear CE marking.

APPLICATIONS

The SCM810 has numerous applications in sound rein forcement, audio recording, and broadcast. In any speech pickup application where multiple microphones are required, the SCM810 dramatically improves audio quality. Automatic operation allows an individual talker's voice to rise above background noise and reverberation to become clearer and more intelligible. Each SCM810 handles up to eight microphone- or line-level signals and two aux-level signals. Any high quality, low-impedance, balanced dynamic or condenser microphone (in cluding wireless) can be used. Additional SCM810 mixers (up to 50) can be interconnected using the rear-panel link jacks. Non-automatic (manual) operation is also available.

REPLACEMENT PARTS

Knob, Master & Phones (white).95A8238 Knob, Channel Gain (blue)..95B8238 Line (Power) Cord (SCM810)..95A8389 Line (Power) Cord (SCM810E).95A8247 Link Cable... 95A1143
SHURE Incorporated http://www.shure.com United States, Canada, Latin America, Caribbean: 5800 W. Touhy Avenue, Niles, IL 60714-4608, U.S.A. Phone: 847-600-2000 U.S. Fax: 847-600-1212 Intl Fax: 847-600-6446 Europe, Middle East, Africa: Shure Europe GmbH, Phone: 49-7131-72140 Fax: 49-7131-721414 Asia, Pacific: Shure Asia Limited, Phone: 852-2893-4290 Fax: 852-2893-4055