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Model SCM810/M810E
User Guide
SCM810/SCM810E
EIGHT-CHANNEL MICROPHONE MIXER
©2005, Shure Incorporated Printed in U.S.A.
27C8504 (Rev. 8)
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TABLE OF CONTENTS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 SYSTEM FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 OPERATING PRINCIPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 FRONT PANEL FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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DESCRIPTION The Shure Model SCM810/E is an eight-channel automatic microphone Each input channel has a two-band equalizer and three logic terminals. The mixer designed for use in sound reinforcement, audio recording, and equalizer reduces unwanted low-frequency audio pickup and makes differ- broadcast applications. The SCM810 dramatically improves audio quality ent microphone types-lavaliers, boundary and handheld-sound similar. The in any application where multiple microphones are required. Any
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FRONT PANEL FEATURES MODEL SCM810 FRONT PANEL FIGURE 1 Microphone Channel Gain Controls 1 - 8: Allows adjustment of Aux INPUT 1/4-inch Phone Jack: Mixes external auxiliary- or microphone gain. line-level sources into output. This out is not automatic. Signal appears at output of all linked mixers. Input LED 1 - 8: Lights green when channel is active; lights red at 6 dB below clipping level. MASTER Level Control: Determines the overall mix level. Low-Cut Filter 1 - 8
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DIP SWITCHES The rear-panel DIP switch provides the following setup options. The posi- NOTE: Switch positions and effects are shown in Figure 3 and also on the tions shown in bold type are the factory settings. mixer label. DIP SWITCH SW702 (MIXER REAR PANEL) 1 2 3 4 5 6 7 MODIFIABLE FUNCTION SWITCHES FIGURE 3 DIP SWITCH SW702 FUNCTIONS Switch Last Mic Off-Attenuation Limiter Link Manual/Auto Hold Time Function Lock-On Level Threshold Local/Global Switch Position 1 2 3 4 5,6 7 Number → 5 Up
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INSTALLATION AND SYSTEM SETUP RACK MOUNTING THE MIXER To mount the SCM810 in a standard 483 mm (19-inch) audio equipment rack, slide the mixer into the rack and secure it with the supplied Phillips head screws, as shown in Figure 4. Use all four screws. RACK MOUNTING THE SCM810/E FIGURE 4 SCM810/E CONNECTIONS Make audio connections as follows (see Figure 5). TO STEREO OR MONO HEADPHONES 1. Connect microphone- or line-level signal sources to the Channel Input FROM AUX– OR LINE–LEVEL SOURCE conne
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EQUALIZER FUNCTIONS Low Cut Filter (High-Pass) +2 The low-cut (or high-pass) filter allows all frequencies above its cutoff point FULL CW to pass from filter input to filter output without attenuation, while frequencies 0 below the cutoff are attenuated (see Figure 6). The cutoff point is defined -2 as the frequency where the signal has dropped 3 dB relative to the flat, or -4 bandpass, region. Below the cutoff point, the filter exhibits increasingly more attenuation as the frequency diminishes.
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NETWORKING MULTIPLE MIXERS If additional inputs are needed, more SCM810 mixers (as many as 50) can As long as the link jacks of all mixers are connected (out-to-in, sequentially, be “linked” using supplied link cables. Such a configuration can provide up leaving one Link In and one Link Out jack unconnected), the automatic mix- to 400 microphone inputs. ing functions will be shared by all units. All input signals appear at all linked mixer outputs. There is no master/slave relationship. To link
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SPECIFICATIONS Measurement Conditions (unless otherwise specified): Line voltage 120 Input Channel Activation Vac, 60 Hz (SCM810) or 230 Vac, 50 Hz (SCM810E); full gain; 1 kHz, one Attack Time 4 ms Hold Time0.4 s (Switchable to 1.0 s) channel activated; source impedances: Mic 150 Ω, Line 150 Ω; termina- Decay Time0.5 s tions: Line 10 k Ω, Phones 300 Ω (tip-sleeve and ring-sleeve), Direct Out 10 Off-Attenuation k Ω; Auto mode, equalization controls adjusted for flat response 15 dB (switchable to
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ADVANCED FUNCTIONS The SCM810's Advanced Functions are recommended only for those who are technically knowledgeable and familiar with audio electronics. LOGIC CONNECTION SPECIFICATIONS The logic functions of the SCM810 expand the mixer's range of installation Logic controls are accessed at the DB-25 multi-pin connector on the rear and control options. Logic can be used for everything from simple cough panel (Figure 11). The pin connections are given in the following table. switches to elaborat
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SUGGESTED LOGIC APPLICATIONS This section contains suggestions on the uses of the SCM810's logic capa- Remote Channel-On Indicators bilities. Note that uses of these functions are not limited to the listed appli- Remote indicators can be used to indicate when a talker's microphone is cations. The user is limited only by individual imagination and creativity. For on. Connect the LEDs and a 5-volt supply to the GATE OUT pins as shown additional suggestions and solutions to installation problems, c
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Inhibiting Gating for Unwanted Sounds As described in the Operating Principles section, MaxBus attempts to acti- vate only one microphone per sound source. Muting a microphone channel + prevents its audio from appearing at the mixer's output. However, the mut- 12 V ed microphone still communicates with other mic channels via MaxBus. A POWER sound source picked up by a muted microphone will not activate other mi- SUPPLY crophones. – Sound sources that may cause unwanted microphone channel activat
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Mixer logic may be used with 15-volt CMOS logic if a pull-up resistor is Diode Isolation of Logic Controls used with each GATE output (see Figure 20-Channel 1 modified). 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 15 V 5 modified). 5.1 K POWER SUPPLY – D = 1N4148 OR GROUP EQUIVALENT MUTE CMOS LOGIC GATES GROUND M1 M3 M5 ÑÑÑÑ
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INTERNAL MODIFICATIONS WARNING: All modifications must be performed by qualified service tech- 3. For individual channel modifications, the first number of the reference nicians. designation refers to its channel number, i.e., R1027 refers to a Chan- nel 1 resistor, X7216 refers to a Channel 7 jumper, etc. All references This section describes SCM810 modifications that can be made using sol- to Channels 1 through 8 in the following paragraphs use Channel 1 der “jumpers” on the printed circuit bo
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SCM810 Speech Gate for Mixing Console The SCM810 can be used in conjunction with large mixing consoles to pro- Procedure: Short jumpers X103, X107, X108 and X906 (in the Master sec- vide automatic mixing for talk shows, panel discussions, and news shows. tion). Remove resistors R1011, R1019, and R1020. 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 unba
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Increase Hold Time In addition to the dip switch SW702 options of 0.4- and 1.0-second hold Procedure: Install a 470 k Ω resistor across jumper points X902. Move DIP time, the hold time can be increased to 1.5 seconds. (More than 1.5 sec- switch down to 1.0-second position. onds is not recommended.) Decrease Hold Time The hold time can be decreased from the factory preset of 0.4 seconds to Procedure: Install a 2 M Ω resistor at jumpers X903. 0.3 seconds. (Less than 0.3 seconds is not recommended.
