The Shure Model SCM800 is a full-featured, eight-channel microphone mixer for sound reinforcement, general audio recording, and audio-visual systems. Any low-impedance, balanced dynamic or condenser microphone, including a wireless microphone system, can be used with the SCM800 mixer.
Each SCM800 accepts up to eight microphone- or line–level
inputs and one aux-level input (two input jacks feed the same
channel). Up to four SCM800 mixers can be linked to provide
up to 32 input channels. Each input channel has a two-band
equalizer, switchable microphone- or line-level operation,
FEATURES
S Compatible with Shure SCM810 and FP410 automatic mi-
crophone mixers
S Adjustable EQ per channel: low-frequency rolloff and high-
frequency shelving
S 48 V phantom power selectable for each input
S Active balanced microphone- and line-level inputs and line-
level output
S Highly RF-resistant chassis and circuitry
S LED indication of channel clipping
SCM800 FRONT PANEL
switchable 48 V phantom power, and a 1/4-inch send/receive
insert jack.
The SCM800 operates on 120 Vac power; the SCM800E operates 230 Vac power. Both models are supplied with rackmounting hardware, link cable and removable block terminal
connectors. An accessory rack panel adapter (Model
RKC800, available separately) converts the removable block
input and output connectors to XLR connectors, and the Aux
connectors to phono jacks.
S Linking capability for systems up to 32 microphones
S Two Aux-level input jacks that feed one channel
S Insert jack on each channel
S Manual mixing of input channels
S Internal Modification permits 230 V operation (SCM800) or
120 V operation (SCM800E)
S Front-panel headphones output with level control
S Peak-responding output limiter with selectable thresholds
and LED indicator
1257810
369
1. Microphone Channel Gain Controls 1 - 8: Allows adjustment of microphone gain.
2. Input LED 1 - 8: Lights red at 6 dB below clipping level.
4. High-Frequency Shelving Filter 1 - 8: Recessed screw-
driver adjustment provides level boost or cut in mid/highfrequency region for compensation of off-axis lavalier microphones, or for cutting the high-frequency sibilance of
vocal microphones.
5. AUX Level Control: Sets the input level for aux-level
equipment connected to the adjacent
INPUT or rear-panel
4
1
/4-inch AUX input.
MODEL SCM800/E FRONT PANEL
FIGURE 1
6. AUX INPUT
iary- or line-level sources, i.e., tape recorders, into output.
Signal appears at output of all linked mixers.
7. MASTER Level Control: Determines the overall mix level.
8. Output Level Meter: Nine-segment LED meter indicates
peak output signal level. Last LED indicates limiter action.
9. PHONES Control and
monitoring of mixer output through headphones.
PHONES control determines headphones output level.
10. POWER LED: Lights green when unit is powered.
1
/4-inch phone jack
1
/4-inch Phone Jack: Mixes external auxil-
1
/4-inch Phone Jack: Permits
3
SCM800 REAR PANEL
120VAC 50/60 Hz 200mA
LINK
OUT
AUX/INS/INS
LINK
IN
(SWITCH)
LINE
OUTPUT
INSERT
AUX IN
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
INSERT
MIC/PHM/LINE
SWITCH
78
Ć
+
111217
13
Ć
+
1415
16
MODEL SCM800/E REAR PANEL
FIGURE 2
11. SCM800: 120 VAC Power Connector and Rocker
Switch: Switch turns unit on when power cord is plugged
into 120 Vac. Can be internally changed to 230 V operation (see Voltage Selection).
SCM800E: 230 VAC Power Connector and Rocker
Switch: Switch turns unit on when power cord is plugged
into 230 Vac. Can be internally changed to 120 V operation (see Voltage Selection).
12. DIP Switch: The 7-position DIP switch provides control
of the output limiter threshold (see DIP Switches).
13. LINK IN/OUT Jacks: Permit multiple SCM800 mixers to
be stacked for additional inputs.
14. LINE OUTPUT Removable Block Connector: Active
balanced line-level signal for connection to amplifiers, recorders or other mixers. If necessary, output level can be
changed to microphone level. Refer to the Internal Modifi-cations section of this manual.
Ć
+
Ć
+
ĆĆ
+
18
Ć
+
MICĆ
+
LEVEL
Ć
+
123456
+
PHANTOM
(PHM)
(MIC)
(SWITCH BEHIND
CONNECTOR)
1
15. SEND/RECEIVE
/4-inch Insert Jacks: Post-fader,
post-EQ insert point to add external compressor/limiter,
graphic or parametric EQ, or other signal processors. Tip
is send, ring is return. Can be modified for use as a Direct
Out (see Internal Modifications).
16. AUX/INS/INS 3-Position Slide Switch: Selects either
aux input function or insert function for channel 8 (only) Insert jack. Left switch position is AUX IN; center and right
positions are INSERT. This switch is located behind Line
Output connector.
17. INPUT 1-8 Removable Block Connectors: Active balanced microphone- or line-level inputs.
18. Input 1 - 8 MIC/PHM/LINE 3-Position Slide Switch: Se-
lects operation at either microphone-level (left), microphone-level with 48 V phantom power (center), or line-level (right) signals. This switch is located behind the removable block connector.
Ć
LINEĆ
LEVEL
(LINE)
44
SYSTEM SETUP
RACK MOUNTING THE SCM800/E
To mount an SCM800 or SCM800E in a standard 483 mm
(19-inch) audio equipment rack so that the front panel faces
out, as shown in Figure 4. Then secure secure the mixer to the
rack with the four supplied Phillips head screws.
SCM800/E CONNECTIONS
Refer to Figure 5 and proceed as follows:
1. Connect microphone- or line-level signal sources to the
Channel Input connectors (use conventional two-conductor shielded cables).
2. Insert a screwdriver or similar tool into the slot above each
block connector and adjust the input slide switch as required: microphone level (left position), 48 V phantom
power (center position), or line level (right switch position).
3. Connect the Line Level Output of the SCM800/E to the
input of other mixers, equalizers, amplifiers, or recorders.
If multiple SCM800/E mixers are to be used, refer to the
Mixer Linking paragraph of this manual.
4. If headphone monitors are to be used, plug them into
5. Connect the power cord to a 120 Vac (SCM800) or 230
NOTE: For instructions on how to change the operating voltage of either model, refer to the Internal Modifications section
of this manual.
1
/4-inch PHONES jack on the front-panel.
the
Vac (SCM800E) power source.
RACK MOUNTING THE SCM800/E
FIGURE 4
TO STEREO OR MONO HEADPHONES
FROM AUX– OR LINE–LEVEL SOURCE
MIXER OUTPUT TO AMP/REC/MIXER INPUT
TO POWER SOURCE
SCM800/E AUDIO CONNECTIONS
FIGURE 5
TO AMP/REC/MIXER INPUT (CH. 1–7)
FROM MIC/LINE SOURCE (CH. 1–8)
TO AMP/RECORD/MIXER INPUT
OR FROM AUX SOURCE (CH. 8)
TO LINKED SCM800 MIXERS
OUTPUT LIMITER THRESHOLD SETTINGS
The DIP switches on the rear-panel, shown below in Figure 3,
control the output limiter threshold settings. Switches 5 and 6
change the output limiter threshold to OFF (default setting),
+16 dBm, +8 dBm, or +4 dBm. Other settings are as shown in
the table at right. Refer to the Internal Modifications section of
this manual for additional settings.
NOTE: Switches 1, 2, 3, 4 and 7 are inactive and are not used.
(MIXER
REAR
PANEL)
OUTPUT LIMITER THRESHOLD DIP SWITCH
1 2 3 4 5 6 7
FIGURE 3
DIP SWITCH FUNCTIONS
DIP Switch PositionLimiter Threshold
5 Up
6 Up
5 Down
6 Up
5 Up
6 Down
5 Down
6 Down
5
Limiter Off
(default)
+8 dBm
+16 dBm
+4 dBm
LINKING MULTIPLE SCM800 MIXERS
Up to four SCM800 mixers can be “linked” using the supplied
link cables If additional inputs are needed. Such a configuration can provide 32 mic inputs. Refer to Figure 6.
When multiple SCM800 mixers are linked, 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. 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.
Link jacks should be connected sequentially: the LINK OUT of
one mixer to the LINK IN of the next, leaving one LINK OUT
and one LINK IN unconnected.
NOTE: Each doubling of the number of linked mixers decreases the master output level by 6 dB.
LINKING TO OTHER SHURE AUTOMATIC MIXERS
An SCM800 can be interfaced with Shure SCM810 and FP410
automatic microphone mixers via the link jacks. Linking an
SCM800 is equivalent to adding an additional mixer with eight
open microphones to a system. Because of the loading effects
of additional open microphones, only one SCM800 can be
linked to an automatic system. When using more than one
SCM800 with other Shure automatic mixers, connect them as
described in the following section.
NOTE: When linking an SCM800 to an automatic system, use
the SCM800 LINK OUT jack to interface with the LINK IN jack
of the automatic system (see Figure 7).
LINKING MULTIPLE SCM800/E MIXERS
FIGURE 6
USING AN SCM800 AS A SUBMIXER
The master output of the SCM800 (or the output of a mixer in a
group of linked SCM800 mixers) can be connected to a channel input or the aux input of an automatic mixer, or other types
of mixers. See Figure 8.
ADDITIONAL LINK CABLES
Additional 381 mm (15 in.) link cables are available as Shure
Part No. 95A8889. 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.”
LINKING AN SCM800/E TO OTHER AUTOMATIC MIXERS
FIGURE 7
SCM800
OUTIN
SCM800
IN
LINE OUT
MIC IN
SCM810
USING AN SCM800/E AS A SUBMIXER
FIGURE 8
66
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 Low-Cut and High-Frequency controls adjacent to each Input Gain control until all microphones
sound alike.
LIMITER
The SCM800’s output limiter prevents distortion during loud
program peaks without affecting normal program levels. Increasing the individual or Master level controls will increase
the average output and, in turn, the amount of limiting. The limiter prevents excessive overloading of devices connected to
the SCM800 output. As supplied, the limiter is defeated.
EQUALIZER FUNCTIONS
Low Cut Filter (High-Pass)
The low-cut (or high-pass) filter allows all frequencies above
its cutoff point to pass from filter input to filter output without attenuation, while frequencies below the cutoff are attenuated
(see Figure 9). The cutoff point is defined as the frequency
where the signal has dropped 3 dB relative to the flat, or bandpass, region. Below the cutoff point, the filter exhibits increasingly more attenuation as the frequency diminishes. The rate
at which this attenuation occurs is defined in decibels per octave (dB/oct). The SCM800 has a one-pole, low-cut (highpass) filter of 6 dB per octave.
Low-cut filters are ideally used for attenuating, or rolling off, the
audio signal where extraneous noise, excessive proximity effect, or other unwanted material is present. For example, the
low-frequency vibration cause by footsteps and vehicle traffic
can be transmitted through microphone stands to the microphone, and then into the sound system. These frequencies,
typically ranging from 5 to 80 Hz, are generally not desirable.
+2
FULL CW
0
-2
-4
-6
-8
-10
201001,0005,000
50%
ROTATION
FULL CCW
FREQUENCY (Hz)
5. Adjust the SCM800 Master level control for the desired
output level, as indicated by the output peak meter.
6. Adjust the headphones volume level with the PHONES
control knob.
The limiter threshold can be set for a peak output level of +4,
+8, or +16 dBm. With the threshold set at +16 dBm, the mixer
has 12 dB of headroom at a nominal level of +4 dBm. Refer to
the Internal Modifications section for information on how to
change the limiter’s settings.
High-Frequency Shelving
The fixed-frequency equalizer produces a 6 dB boost or cut at
5 kHz and above (see Figure 10). 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.
Line voltage 120 Vac, 60 Hz (SCM800) or 230 Vac, 50 Hz
(SCM800E); full gain; 1 kHz.
Source impedances: Mic 150
Terminations: Line 10 k:, Phones 300 :tip-sleeve and ringsleeve), Direct Out 10 k
Equalization controls adjusted for flat response, Channel 1
gain control full clockwise, other gain controls full counter-
clockwise
Frequency Response (Ref .1 kHz, channel controls centered)
50 Hz to 20 kHz r2 dB; -3 dB corner at 25 Hz
Voltage Gain (typical, controls full clockwise)
InputLineHead-
Low-impedance
mic (150 :)
Line40 dB48 dB–6 dB
Aux44 dB52 dB—
Send/Return20 dB28 dB—
80 dB88 dB34 dB
Inputs
Input
Mic19-600 :10 k:-15 dBV
Line
Aux
Send/Return
Designed
for use with
d2 k:
d2 k:
d2 k:
Outputs
Output
Line>600 :60 :+18 dBV
Headphones8-200 :,
Direct Out>2 k:1 k:+18 dBV
Send/Return>2 k:1 k:+18 dBV
Designed
for use with
60 : recom-
mended
Total Harmonic Distortion
<0.1% at +18 dBV output level, 50 Hz to 20 kHz (through 20
Hz-20 kHz filter; Input 1 and Master at 5, all other controls full
counterclockwise)
Hum and Noise
Equivalent Input Noise: -125 dBV (150 : source; through
Equivalent Input Hum and Noise: -123 dBV (150 : source;
Output Hum and Noise (through 20 Hz to 20 kHz filter;
channel controls full counterclockwise):
Master full counterclockwise: -90 dBV
Master full clockwise: -62 dBV
:, Line 150 :
:
Output
phones
Impedance
Actual
(typical)
10 k:+22 dBV
10 k:+22 dBV
10 k:+18 dBV
Impedance
Actual
(typical)
300 :+12 dBV
400 Hz–20 kHz filter)
through 20 Hz - 20 kHz filter)
Direct Out
Input
Clipping Level
Output
Clipping Level
Common Mode Rejection
>70 dB at 1 kHz
Polarity
Mic/Line, Send inputs to all outputs are non-inverting; Aux
input to all outputs is inverting
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-frequency: r6 dB at 5 kHz, r8 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
Light at 6 dB below clipping
Phantom Power
46 Vdc open-circuit through 6.8 k
: series resistance per
DIN 45 596
Operating Voltage
SCM800: 120 Vac rated nominal (see Voltage Selection
for 230 Vac operation), 50/60 Hz, 200 mA
SCM800E: 230 Vac rated nominal (see Voltage Selection
for 120 Vac operation), 50/60 Hz, 100 mA
Temperature Range
Operating: 0
Storage: -30
Overall Dimensions
44.5 mm H x 483 mm W x 317 mm D (1
q to 60q C (32q to 140q F )
q to 70q C (-22q to 158q F)
3
/4 x 19 x 121/2 in.)
Net Weight
4.3 kg (9 lb 9 oz)
Certifications
SCM800: Listed by Underwriters Laboratories, Inc.; listed
as Certified by Canadian Standards Association
SCM800E: Conforms to European Union directives; eligible
to bear CE marking; VDE GS-Certified to EN 60950;
EU EMC Immunity Requirements: EN50082-1
For additional service or parts information, please contact
the Shure Service Department at 1-800-516-2525. Outside
the United States, please contact your authorized Shure
Service Center.
*For systems requiring other mains connectors, use a power cord with
an IEC 320 type mating connector for connection to the SCM800, and
an appropriate plug on the other end for connection to the mains. The
supplied cord uses Harmonized IEC Cordage with color coding as follows: Brown = Line, Blue = Neutral, Green/Yellow = Ground.
88
INTERNAL MODIFICATIONS
WARNING: All modifications must be performed by quali-
fied service technicians. Voltages in this equipment are hazardous to life. No user-serviceable parts inside. Refer all
servicing to qualified service personnel. The safety certifications of the SCM800 do not apply when the operating voltage is changed from the factory setting.
ABOUT PRINTED CIRCUIT BOARD MODIFICATIONS
S A jumper is represented by “X” on the printed circuit
board legend, a resistor is represented by an “R.”
S The first number in the reference designator indicates
the channel number; i.e., R1027 refers to a Channel 1
resistor, and X7216 refers to a Channel 7 jumper, etc.
S Components in the Master section are preceded by
the number “9” (X901, etc.).
S The circuit board contains holes where resistors are
to be added.
S A single drop of solder can serve as a jumper between
adjacent jumper pads.
S All Channel modifications in this section use
Channel 1 as an example.
REMOVING THE TOP COVER
To gain access to the main printed circuit board, remove the
eight Phillips head screws securing the top cover to the chassis and remove it. Most internal modifications can be made
from the top of the main board.
MODIFYING THE SCM800 FOR 220–240 VAC, 50/60 HZ OPERATION
The SCM800 can be internally modified to operate on 230 Vac,
50/60 Hz power.
NOTE: The supplied cord uses Harmonized IEC Cordage with
the following color coding: Brown = Line, Blue = Neutral,
Green/Yellow = Ground. For systems requiring other mains
connectors, obtain a power cord with an IEC 320 type mating
connector for connection to the SCM800, and an appropriate
plug on the other end for connection to the mains.
Procedure:
1. Disconnect the SCM800 from the AC power source.
2. Remove the top cover.
3. Locate Voltage Selector switch SW903 adjacent to power
transformer T901. Use a screwdriver to turn the center rotor on the SW903 to the 230V position.
4. Locate Fuse F901 and remove it. Replace it with a 100
mA, 250 V, time delay fuse for 230V operation. Fuse part
numbers are listed in following table:
Fuse TypeShure Part No.Littelfuse Part No.
100 mA, 250 V80C258218.100
200 mA, 250 V80BC8196239.200
5. Replace the power cord with a cord rated for for 230V operation, i.e., an IEC appliance connector on the equipment end and a CEE 7/7 (“Schuko”) mains connector on
the other.
MODIFYING THE SCM800E FOR 100–120 VAC, 50/60 HZ OPERATION
The SCM800E can be internally modified to operate on 120
Vac, 50/60 Hz power.
NOTE: The supplied cord uses Harmonized IEC Cordage with
the following color coding: Brown = Line, Blue = Neutral,
Green/Yellow = Ground. For systems requiring other mains
connectors, obtain a power cord with an IEC 320 type mating
connector for connection to the SCM800E, and an appropriate
plug on the other end for connection to the mains.
Procedure:
1. Disconnect the SCM800E from the AC power source.
2. Remove the top cover.
3. Locate Voltage Selector switch SW903 adjacent to power
transformer T901. Use a screwdriver to turn the center rotor on the SW903 to the 120V position.
4. Locate Fuse F901 and remove it. Replace it with a 200
mA, 250 V time delay fuse for 120 V operation. Fuse part
numbers are listed in the following table:
Fuse TypeShure Part No.Littelfuse Part No.
200 mA, 250 V80BC8196239.200
100 mA, 250 V80C258218.100
5. Replace the power cord with a cord rated for 120V operation, i.e., an IEC appliance connector on the equipment
end and a mains connector suitable for 120V operation on
the other.
9
INSERTING A 15 dB MICROPHONE PREAMPLIFIER PAD
Each channel’s microphone preamplifier gain can be reduced
by 15 dB. This may be desirable with extremely high-output microphones.
LINE-LEVEL OUTPUT TO MIC-LEVEL OUTPUT
DISABLE MASTER LEVEL CONTROL
The Master gain control can be disabled so it cannot be tampered with. The following table indicates the resistor value to
be used for the desired gain.
Master Section GainResistance
-6 dB5.1 k:
010 k:
6 dB20 k:
Procedure:
To pad the gain of the MIC position
1. Remove surface mount resistor R1023.
2. Solder a 680 : resistor at jumper X112. For a greater gain
reduction, use a resistor with a value greater than 680 :.
Use a lesser value resistor for less reduction.
To pad the gain of the PHM (phantom) position:
1. Remove surface mount resistor R1026.
2. Solder a 1.5 k: resistor at jumper X110. This reduces
gain by 8 dB. For a greater gain reduction, use a resistor
with a value greater than 1.5 k:. Use a lesser value resistor for less reduction.
NOTE To compensate for higher output condenser microphones, the factory set gain in the PHM position is 13 dB lower
than the gain in the MIC position.
Procedure:
1. Short jumper X901.
2. Remove resistors R900 and R909.
Procedure:
1. Remove resistor R9230.
2. Install new resistor at jumper X914.
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:
1. Remove resistors R9177 and R9180.
2. 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.
SEND/RETURN (INSERT) TO DIRECT OUT
Changes a channel’s 1/4-inch insert jack to a Direct Out jack.Procedure:
1. Remove resistors at X101, X102, X105 and X106, and
X808 if modifying channel 8.
2. Short jumpers R1011 and R1020.
SEND/RETURN TO DIRECT OUT POST-FADER
A channel’s Insert phone jack can be changed to Direct Out,
post-fader.
Procedure:
1. Remove resistors at X101, X102 and X105.
2. Short jumpers at R1020.
1010
REMOTE VOLUME CONTROL OF CHANNELS
The channel, aux, or master levels can be controlled remotely
by a dc voltage via an external VCA (Voltage Controlled Amplifier). An example of an external VCA is the ST-VCA1 from Radio Design Labs (1–800–281–2683 or www.rdlnet.com).
Procedure:
For channel control:
1. Connect the tip of a 1/4-in. connector to the line input of
the VCA, and the sleeve to the ground of the VCA.
2. Connect the ring to the line output of the VCA.
3. Plug the 1/4-in. connector to the Insert jack of the
SCM800.
4. Set the channel level control should be set to 5.
For Aux In control:
1. Connect the external source to the VCA line input.
2. Connect the VCA line output to the tip and sleeve of the
SCM800 Aux input.
3. Set the Aux control to 5.
For Master control:
1. Connect SCM800 Line output to the VCA line input.
2. Connect the VCA line output to the external device (amplifier, tape recorder, etc.).
3. Set Master control to 5.
11
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
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