Shure SCM262 User manual

SCM262
Stereo Mixer
SCM262 Stereo Mixer User Guide
27B8607 (AF)
2001, Shure Incorporated Printed in U.S.A.

This symbol indicates that dangerous voltage constituting a risk of electric shock is present within
this unit.
Ce symbole indique la présence d’une tension dangereuse dans l’appareil constituant un risque
de choc électrique.
Dieses Symbol zeigt an, daß gefährliche Spannungswerte, die ein Stromschlagrisiko darstellen,
innerhalb dieses Geräts auftreten können.
Este símbolo indica que la unidad contiene niveles de voltaje peligrosos que representan un ries-
go de choques eléctricos.
Questo simbolo indica che all’interno dell’apparecchio sono presenti alte tensioni, che comporta-
no il rischio di folgorazione.
This symbol indicates that there are important operating and maintenance instructions in the liter-
ature accompanying this unit.
Ce symbole indique que la documentation fournie avec l’appareil contient des instructions d’utili-
sation et d’entretien importantes.
Dieses Symbol zeigt an, daß das diesem Gerät beiliegende Handbuch wichtige Betriebs– und
Wartungsanweisungen enthält.
Este símbolo indica que la literatura que acompaña a esta unidad contiene instrucciones impor-
tantes de funcionamiento y mantenimiento.
Questo simbolo indica che il manuale di questo apparecchio contiene importanti istruzioni di uso
e manutenzione.

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SHURE SCM262
DESCRIPTION
The Shure Model SCM262 is a stereo mixer intended for
sound reinforcement applications that integrate microphones
with consumer stereo products. It incorporates two
active-balanced microphone inputs with three unbalanced
stereo aux level inputs.
The SCM262 Stereo Mixer is designed for restaurants,
classrooms, corporate training, aerobics classes, and other
situations where a paging/public announcement system is
combined with background music or other program material.
FEATURES
•Designed to combine paging with background music.
•One active-balanced, XLR microphone input channel.
•One active-balanced XLR microphone and 1/4-in. TRS
line input channel.
•Three STEREO INPUT channels
•Stereo AUX level OUTPUTs
•Stereo MIC/LINE OUTPUTs
•BASS and TREBLE tone controls on the master output.
•1/2-rack chassis.
•12 V phantom power for condenser microphones.
•Internal power supply.
•Removable power cable.
•Ducking function (defeatable).
•Jukebox mute function (defeatable).
FRONT PANEL
ÍÎÊË Ì
ÊMIC Channel Gain Controls, 1–2. Control the gain
levels of the MIC channels and LINE IN 2 (MIC 2).
ËSTEREO Channel Gain Controls, 1–3. Control the gain
levels from CD players, juke boxes, VCRs, or other
consumer stereo equipment connected to the STEREO
inputs.
ÌBASS and TREBLE Controls. Control the boost/cut of
the low- and high-frequency of the shelving filters.
ÍMASTER Gain Control. Allows adjustment of the overall
output gain.
ÎPOWER Indicator. Lights up to indicate when the unit is
plugged in and receiving power.
NOTE: The SCM262 does not have a power switch. To
turn the unit off, unplug the power cord or use an external
power strip with a switch. However, it can remain plugged
in as it uses very little power when idle.
REAR PANEL
ÐÎÊË ÍÌÏ
ÊPower Connector. Accepts 100–120 Vac (SCM262) or
220–240 Vac (SCM262E).
ËLeft/Right MIC/LINE Output Connectors. These 1/4-in.
connectors are stereo, balanced outputs for use with
professional audio equipment. Controlled by DIP switch.
ÌLeft/Right AUX Output Connectors. These phono jacks
are stereo, unbalanced outputs for use with consumer
stereo equipment.
ÍDIP Switches. These allow you to adjust the SCM262 for
specific applications. See DIP Switches.
ÎLeft/Right STEREO INPUTS, 1–3. These phono jacks
are stereo inputs for connection to consumer stereo
devices.
ÏMIC Channel 2 INPUT. Microphone channel 2 has two
available inputs. There is a 1/4-in. connector for balanced/
unbalanced line-level connections, or an XLR connector
for balanced mic-level connections.
ÐMIC Channel 1 INPUT. This is an XLR connector for
balanced mic-level connections.

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DIP SWITCHES
DIP FUNCTION POSITION
SWITCH UP (default) DOWN
1LEFT OUTPUT MIC/LINE Line Mic
2RIGHT OUTPUT MIC/LINE Line Mic
3MIC 1 DUCKING Off On
4MIC 2 DUCKING Off On
5DUCKING LEVEL –1–20 dB
6STEREO 3 JUKEBOX MUTE Off On
712 V PHANTOM Off On
LEFT/RIGHT OUTPUT MIC/LINE: DIP switches 1 and 2
adjust the left and right outputs for line- or mic-level operation.
MIC 1/MIC 2 Ducking: When ducking is on, the SCM262
will automatically lower the gain of all STEREO inputs when
someone is speaking into one of the microphones.
DUCKING LEVEL: Adjusts the amount of STEREO
channel gain reduction when ducking is activated.
STEREO 3 JUKEBOX MUTE: This DIP switch turns the
Juke Box Mute feature on or off. When on, any source
connected to STEREO 3 will mute STEREO 1 and 2 inputs.
PHANTOM POWER: When in the down position, this
switch activates a 12 V phantom power source for condenser
microphones. Phantom power does not affect the operation of
balanced, dynamic microphones, so one can be connected to
the SCM262 in combination with a condenser microphone.
APPLICATIONS
General Application
This is a general setup for most situations which require
the combined use of professional microphones and consumer
stereo equipment. Using this general setup, there are several
other options available for further adjusting the SCM262 for
your sound system. See the diagram on the facing page.
1. Turn all gain controls counterclockwise.
2. Connect L/R STEREO INPUTS of the SCM262 to the L/R
stereo outputs of the desired stereo audio equiment (CD
players, VCRs, televisions, juke boxes, etc.).
3. Connect microphone(s) to the MIC INPUTS on the
SCM262.
4. For microphones which require phantom power, such as
condenser microphones, place DIP switch 7 in the down
position (phantom power on).
5. Connect the L/R outputs of the SCM262 to the L/R inputs
of the amplifier.
NOTE: If you are using a consumer stereo amplifier,
use the AUX OUTs. If you are using a professional
audio power amplifier, use the LINE OUTs. The
MIC/LINE and AUX OUTPUTs can be used
simultaneously to feed two separate amplifiers.
6. Apply power to the mixer by connecting the supplied
power cable between the power connector on the mixer
and the appropriate AC power supply. The green
POWER LED will illuminate to indicate that the mixer is
powered on.
NOTE: The SCM262 has no power switch. It is
designed to be plugged into a power strip which
supports the whole sound system. A typical power strip
will have a power switch, so that when the power strip is
powered on, the SCM262 is powered on.
Paging with Ducking Application
With Ducking on, the SCM262 will automatically sense
when someone is talking into one of the microphones and
lower the volume of the music so the talker can be heard more
clearly. Once the talker is finished, the music resumes.
NOTE: Use a microphone with an ON/OFF or
pushbutton switch for the Paging with Ducking
Application. A microphone without a switch will
false-trigger, causing unwanted interruptions in the
program material.
1. Connect the SCM262 to the sound system as described
in General Application.
2. Set DIP switch 3 or 4 to the down position to activate
ducking for microphone channel 1 or 2, respectively.
3. Set DIP switch 5 position. The Down position sets the
ducking so that the program sound is lowered 20 dB when
someone uses a microphone. The Up position sets the
ducking so that the program sound is muted when
someone uses a microphone.
Jukebox Mute Application
In this application, designed primarily for Jukeboxes, any
sound source connected to the STEREO 3 channels will
automatically mute any sound coming over the STEREO 1 and
2 channels. This way, a CD player can be playing music, and
then when someone plays a song on the Jukebox, the
SCM262 will automatically mute the CD player channels and
switch to the Jukebox. STEREO 1 and 2 channels will remain
muted for about 30 seconds after program material is finished,
to allow the jukebox time to move on to the next song.
1. Connect the SCM262 to the sound system as described
in General Application.
2. Connect the L/R audio outputs of the jukebox to the L/R
inputs of STEREO 3.
NOTE: This feature is designed especially for use with
jukeboxes, but will work for any equipment connected
to STEREO 3.
3. Set DIP Switch 6 to the down position (Jukebox Mute on).
NOTE: If the ducking application is used in conjunction
with the Jukebox Mute application, then activated
microphones will mute or duck the STEREO 3 input.
DOWN
UP
*DEFAULT SETTINGS SHOWN.

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CONNECTIONS
L/R
MIC/LINE
OUTPUTS
CONSUMER
STEREO
AMPLIFIER
PROFESSIONAL
AUDIO POWER
AMPLIFIER
LOUDSPEAKERS
POWER SUPPLY
VCR
MICROPHONE
WIRELESS MICROPHONE SYSTEM
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OR
LOUDSPEAKERS
TELEVISION
TAPE DECK
AM/FM RECEIVER
CD PLAYER
OR
OR
R L R L
R
L
OR
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OR
VCR
TAPE DECK
VIDEO CAMERA
L R
L R
R
L
MIC INPUT 1
MIC INPUT 2
AUX INPUTS
AUX INPUTS
AUX INPUT 3
L/R AUX OUTPUTS

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INTERNAL MODIFICATIONS
WARNING!
Voltages in this equipment are hazardous to life. No
user-serviceable parts inside. Refer all servicing and
modifications to qualified service personnel.
Disassembly
To access the printed circuit board (pc board) for internal
modifications, use the following steps:
1. Unplug the power cord.
2. Remove the knobs and retainer nuts from the front panel.
3. Remove the two screws at each bottom corner of the front
panel.
4. Remove the four screws at each corner of the back
panel.
5. Slide the back panel and pc board out from the rear of the
chassis.
CAUTION: When reassembling the SCM262, DO NOT
OVERTIGHTEN the knob retainer nuts. Use a minimal amount
of force to secure the nut (0.6–0.8 N⋅m (5–7 in⋅lb)). Damage to
the internal components will result if too much force is used.
Mono Mixer Modification
This modification allows all the inputs to be mixed to a
single mono signal sent over both the left and right outputs.
Short jumper X203.
Phantom Power Disable
This modification disables the phantom power per
channel.
To disable the phantom power from mic 1, remove resistor
R121. To disable the phantom power from mic 2, remove
resistor R122.
15 dB Mic Preamplifier Pad
When a microphone has an extremely high signal, getting
the desired gain might be difficult –– a small turn of the gain
control might change the sound from a whisper to deafeningly
loud. This modification adds a 15 dB Mic preamplifier pad to
allow more accurate gain adjustment with extremely high
microphone signals.
Remove R160 (mic 1) or R183 (mic 2).
Hard Panning MIC Channels
To remove MIC 1 from the left outputs, remove R912. To
remove MIC 1 from the right outputs, remove R913.
To remove MIC 2/LINE 2 from the left outputs, remove
R910. To remove MIC 2/LINE 2 from the right outputs, remove
R911.
Low-Cut Filter
To eliminate the 80 Hz, low-cut filter, remove resistor
R501 (mic 1), or resistor R519 (mic 2). Place a 10 to 33 µF
capacitor in X501 (mic 1) or R502 (mic 2). The polarity of the
capacitor does not matter.
To change the frequency of the low cut filter, remove
resistor R501 (mic 1) or R519 (mic 2), and place the proper
capacitor into X501 (mic 1) or X502 (mic 2) to get the desired
corner frequency.
The following tables list the low-cut frequency corners for
some of the most common capacitor values:
Capacitor
Value Corner Frequency Capacitor
Value Corner Frequency
.033 mF803 Hz .33 mF80 Hz
.047 mF564 Hz .47 mF56 Hz
.068 mF390 Hz .68 mF39 Hz
.1 mF265 Hz 1.0 mF26.5 Hz
.22 mF120 Hz 2.2 mF12 Hz
Ducking Depth
This modification adjusts the level of ducking depth
attenuation of the input channels when ducking is activated.
The aux ducking depth may be changed by removing
resistor R213 and inserting a resistor into jumper X202. Use
the following tables to determine the proper resistor value for
the desired ducking depth.
Ducking
Depth Resistor Value Ducking
Depth Resistor Value
6 dB 4,000 Ω36 dB 20,000 Ω
9 dB 5,000 Ω42 dB 25,000 Ω
15 dB 7,500 Ω47 dB 30,000 Ω
20 dB 10,000 Ω50 dB 33,000 Ω
24 dB 12,000 Ω55 dB 40,000 Ω
29 dB 15,000 Ω
Ducking Threshold
This modification adjusts the threshold for activating the
ducking circuit.
The ducking threshold can be raised or lowered by first
removing resistor R333, and then placing a resistor (R) at
jumper X303. To lower the ducking threshold, use a resistor
value (R) less than 2k ohms. To raise the ducking threshold,
use a resistor value (R) greater then 2k ohms.

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INSTALLATION
Supplied Hardware
S4 rubber feet. For stand-alone installation.
S1 rackmount bracket, long. For half-rack (single unit)
installations.
S1 rackmount bracket, short. For half-rack (single) or
dual-mount installations.
S2 straddle brackets. For dual-mount or fixed installations.
S12 bracket screws, 1/4-in. (6 mm). For securing the
brackets to the chassis.
S4 rackmount screws, 1 in. (2.5 cm). For mounting the
unit in a rack.
S4 plastic washers. For use with the supplied rackmount
screws.
S4 wood screws, 1/2 in. (1.25 cm). For fixed installations.
Bracket Screw
Rackmount Screw Wood Screw
Rackmount Installation
The SCM262 can be mounted as a single unit or
dual-mounted with either another SCM262 or another Shure
half-rack unit such as the SCM268 or DFR11EQ.
1. Attach the rackmount brackets using one of the following
methods:
Single unit (half-rack) installation: Attach the short and
long rackmount brackets to the SCM262 with eight (8) of
the supplied bracket screws.
Dual-mounted installation:
a) Connect the two units together side-by-side using
two (2) straddle brackets. The brackets should
straddle the recessed edges on on the top and
bottom of each chassis. Fasten them using eight (8)
bracket screws.
NOTE: Be sure to use both straddle brackets—one
on the top and one on the bottom.
b) Attach the short rackmount brackets to the outsides
of the combined units with eight (8) of the bracket
screws.
2. After attaching the brackets, mount the unit in an
equipment rack using the supplied rackmount screws and
plastic washers.
Stand-Alone Installation
Adhere the four (4) supplied rubber feet to the bottom of
the unit at each corner. This will keep it from sliding and protect
the table surface.
Fixed Installation
To permanently affix the SCM262 above or below a table,
shelf, or counter top, use the following steps:
1. Fasten the straddle brackets to the recessed edges of the
chassis using four (4) bracket screws.
Top mount: Fasten the straddle brackets to on the
bottom of the unit
Hanging mount: Fasten the straddle brackets to the top
of the unit.
2. Fasten the straddle brackets to the surface using the four
(4) supplied wood screws.
TOP MOUNT
HANGING MOUNT

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SPECIFICATIONS
Measurement Conditions (unless otherwise
specified):Tone controls centered; Line voltage 120 Vac, 60
Hz (SCM262) or 230 Vac, 50 Hz (SCM262E); full gain; 1 kHz,
one channel activated; source impedances: Mic 150 Ω;
Line/Aux 40 Ω, terminations: Line/Mic/Aux 20 kΩ.
Frequency Response (Ref 1 kHz, channel and master
controls centered)
MIC/LINE Inputs: 150 Hz to 20 kHz ±2 dB
AUX Inputs: 20 Hz to 20 kHz ±2 dB
Low-Cut Filter (Microphone inputs only)
3dB down at 80 Hz, 6 dB/octave
Voltage Gain (typical, controls full clockwise)
Output
Input Mic Line Aux
Low-impedance
mic (150 Ω)32 dB 72 dB 60 dB
Line –9 dB 31 dB 19 dB
Stereo –5 dB 35 dB 23 dB
Inputs
Impedance
Input Designed for use
with
Actual
(typical) Input Clipping
Level
Mic (XLR) <600 Ω1.4 kΩ-16 dBV
Line <10 kΩ155 kΩ+24 dBV
Stereo <2 kΩ21 kΩ>28 dBV
Outputs
Impedance
Output Designed for use
with
Actual
(typical) Output Clipping
Level
Mic > 600 Ω3 Ω-22 dBV
Line >5k Ω300 Ω+18 dBV
Aux 10 kΩ1.5k Ω+5 dBV
Total Harmonic Distortion
<0.25% at +4 dBu output level, (through 22 Hz-22 kHz filter;
MIC Input 1 and Master at center, all other controls full
counterclockwise)
Hum and Noise
Equivalent Input Hum and Noise -125 dBV. . . . . . . . . . . .
(150 Ωsource; 22 Hz - 22 kHz)
Output Hum and Noise
(22 Hz to 22 kHz; channel controls full counterclockwise)
Master full counterclockwise -85 dBV. . . . . . . . . . . . . . .
Master full clockwise -60 dBV. . . . . . . . . . . . . . . . . . . . . .
Common Mode Rejection
>70 dB at 1 kHz
Polarity
All inputs to all outputs are non-inverting.
Overload and Shorting Protection
Shorting outputs, even for prolonged periods, causes no
damage. Microphone inputs are not damaged by signals up to
+10 dBV; Line and Aux inputs by signals up to +28 dBV
Equalization
Bass (Low-frequency shelving) ±6 dB. . . . . . . . . . . . . . . . .
(corner frequency at 250 Hz)
Treble (High-frequency shelving) ±6 dB. . . . . . . . . . . . . . . .
(corner frequency at 4 kHz)
Ducking
Mic channels 1 and 2
Levels –20 dB or –RdB. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Activation time 10 ms (typical). . . . . . . . . . . . . . . . . . . . . . .
Mic Deactivation time 2 s (typical). . . . . . . . . . . . . . . . . . . . .
Jukebox Mute Deactivation Time 30 s (typical). . . . . . . . . .
Phantom Power
12 Vdc open-circuit through 680 Ωresistors
Operating Voltage
SCM262: 100–120 Vac, 50/60 Hz, 60 mA
SCM262E: 220–240 Vac, 50/60 Hz, 30 mA
Temperature Range
Operating –7°to 49°C (20°to 120°F ). . . . . . . . . . . . . . .
Storage -29°to 74°C (-20°to 165°F). . . . . . . . . . . . . . . . .
Overall Dimensions
43 x 218 x 162 mm (1.72 x 8.60 x 6.37 in.)
Net Weight:1.1 kg (2 lbs, 5 oz)
Certifications
SCM262: UL, cUL listed by Underwriters Laboratories.
SCM262E: Conforms to European Union directives, eligible to
bear CE marking; VDE GS-Certified to EN 60 065; meets
European Union EMC Immunity Requirements (EN 50082–1:
1992, EN 50082–2: 1992)
Replacement Parts
Knob, Master (blue) 95B8752. . . . . . . . . . . . . . . . . . . . . . . . . .
Knob, Channel Gain (white) 95A8752. . . . . . . . . . . . . . . . . . .
Line (Power) Cords:
SCM262: 100–120 Vac (US/Canada) 95A8762. . . . . . . .
SCM262E: 220–240 Vac (EU) 95A8778. . . . . . . . . . . . . .
Fuse, SCM262
(5x20 mm, 250V, 100mA, time delay) 80B730. . . . . . . . .
Fuse, SCM262E
(5x20 mm, 250V, 40mA, time delay) 80J258. . . . . . . . . . .
Hardware Kit 90AA8100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Link Bars (Bracket) 53A8443. . . . . . . . . . . . . . . . . . . . . . . . . .
Single Mount Kit 53A8484. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual Mount Kit 53B8484. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories
Line (Power) Cord, 230–240 Vac (UK) 95A8713. . . . . . . . . .
Service Statement
For additional service or parts information, please contact
Shure’s Service department at 1-800-516-2525. Outside the
United States, please contact your authorized Shure Service
Center.
SHURE Incorporated Web Address: http://www.shure.com
222 Hartrey Avenue, Evanston, IL 60202–3696, U.S.A.
Phone: [phone] Fax: [phone]
In Europe, Phone: [phone] Fax: [phone]
In Asia, Phone: [phone] Fax: [phone]
Elsewhere, Phone: [phone] Fax: [phone]