|This symbol indicates that dangerous voltage constituting a risk of electric shock is present within this unit.|
|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.
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.
① MIC Channel Gain Controls, 1-2.
Control the gain levels of the MIC channels and LINE IN 2 (MIC 2).
② STEREO 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.
③ BASS and TREBLE Controls.
Control the boost/cut of the low- and high-frequency of the shelving filters.
④ MASTER Gain Control.
Allows adjustment of the overall output gain.
⑤ POWER Indicator.
Lights up to indicate when the unit is plugged in and receiving power.
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.
⑥ POWER Switch.
① Power Connector.
Accepts 100-120 Vac (SCM262) or 220-240 Vac (SCM262E).
② Left/Right MIC/LINE Output Connectors.
These 1/4-in. connectors are stereo, balanced outputs for use with professional audio equipment. Controlled by DIP switch.
③ Left/Right AUX Output Connectors.
These phono jacks are stereo, unbalanced outputs for use with consumer stereo equipment.
④ DIP Switches.
These allow you to adjust the SCM262 for specific applications. See DIP Switches.
⑤ Left/Right STEREO INPUTS, 1-3.
These phono jacks are stereo inputs for connection to consumer stereo devices.
⑥ MIC 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.
⑦ MIC Channel 1 INPUT.
This is an XLR connector for balanced mic-level connections.
|DIP SWITCH||FUNCTION||POSITION UP (default)||POSITION DOWN|
|1||LEFT OUTPUT MIC/LINE||Line||Mic|
|2||RIGHT OUTPUT MIC/LINE||Line||Mic|
|3||MIC 1 DUCKING||Off||On|
|4||MIC 2 DUCKING||Off||On|
|5||DUCKING LEVEL||–∞||-20 dB|
|6||STEREO 3 JUKEBOX MUTE||Off||On|
|7||12 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.
This is a general setup for most situations which require the combined use of a professional microphone 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.
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.
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. (*Power Switch, country dependent).
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.
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.
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.
This feature is designed especially for use with jukeboxes, but will work for any equipment connected to STEREO 3.
If the ducking application is used in conjuction with the Jukebox Mute application, then activated microphones will mute or duck the STEREO 3 input.
Voltages in this equipment are hazardous to life. No user-serviceable parts inside. Refer all servicing and modifications to qualified service personnel.
To access the printed circuit board (pc board) for internal modifications, use the following steps:
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.
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.
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.
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).
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.
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 (mic2), 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|
|.033 µF||803 Hz|
|.047 µF||564 Hz|
|.068 µF||390 Hz|
|.1 µF||265 Hz|
|.22 µF||120 Hz|
|Capacitor Value||Corner Frequency|
|.33 µF||80 Hz|
|.47 µF||56 Hz|
|.68 µF||39 Hz|
|1.0 µF||26.5 Hz|
|2.2 µF||12 Hz|
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|
|6 dB||4,000 Ω|
|9 dB||5,000 Ω|
|15 dB||7,500 Ω|
|20 dB||10,000 Ω|
|24 dB||12,000 Ω|
|29 dB||15,000 Ω|
|Ducking Depth||Resistor Value|
|36 dB||20,000 Ω|
|42 dB||25,000 Ω|
|47 dB||30,000 Ω|
|50 dB||33,000 Ω|
|55 dB||40,000 Ω|
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.
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. Attach the rackmount brackets using one of the following methods:
Be sure to use both straddle brackets-one on the top and one on the bottom.
To permanently affix the SCM262 above or below a table, shelf, or counter top, use the following steps:
Top Mount: Fasten the straddle brackets to the bottom of the unit.
Hanging Mount: Fasten the straddle brackets to the top of the unit.
at 1 kHz
|Mic/Line Switch||150 Hz to 20 kHz ±2 dB|
|Aux Input||20 Hz to 20 kHz ±2 dB|
-6 dB/octave below 80 Hz
1 kHz, +4 dBu out, mix output (MASTER) at +0 dB
150Ω balanced source, A-Weighted
channel controls full counterclockwise, A-Weighted
|Master full counterclockwise||-95 dBV|
|Master full clockwise||-59 dBV|
>70 dB, at 1 kHz
All inputs to all outputs are non-inverting.
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
|Bass (Low-frequency shelving, corner frequency at 250 Hz)||±6 dB|
|Treble (High-frequency shelving, corner frequency at 4 kHz)||±6 dB|
|Mic channels 1 and 2 levels||-20 dB or -∞ dB|
|Activation time||10 ms, typical|
|Mic Deactivation time||2 seconds, typical|
|Jukebox Mute Deactivation Time||30 seconds, typical|
12 Vdc open-circuit through 680 Ω resistors
|SCM262||100–200 V AC, 50/60 Hz, 60 mA|
|SCM262E||220–240 V AC, 50/60 Hz, 30 mA|
|Operating Temperature||-7° – 35° C (20° –95° F)|
|Storage Temperature||-29° – 74° C (-20° –165° F)|
43 x 218 x 162 mm (1.72 x 8.60 x 6.37 in.)
1.1 kg (2 lbs, 5 oz.)
|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|
|Designed for use with||Actual (typical)||Input Clipping Level|
|Mic (XLR)||<600 Ω||1.4 kΩ||-16 dBV|
|Line||<10 kΩ||155 kΩ||+24 dBV|
|Stereo||<2 kΩ||21 kΩ||>28 dBV|
|Designed for use with||Actual (typical)||Output Clipping Level|
|Mic||>600 Ω||3 Ω||-22 dBV|
|Line||>5 kΩ||300 Ω||+18 dBV|
|Aux||≥10 kΩ||1.5 kΩ||+5 dBV|
|Knob, Master (blue)||95B8752|
|Knob, Channel Gain (white)||95A8752|
|Line (Power) Cords: SCM262: 100-120 Vac (US/Canada)||95B8762|
|Line (Power) Cords: SCM262E: 220-240 Vac (EU)||95B8778|
|Fuse: SCM262 (5x20 mm, 250V, 100mA, time delay)||80Z730|
|SCM262E (5x20 mm, 250v, 40mA, time delay)||80M258|
|Link Bars (Bracket)||53B8443|
|Single Mount Bracket||53A8484|
|Dual Mount Bracket||53E8484|
|Line (Power) Cord, 230-240 Vac (UK)||95A8713|
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.
This product meets the Essential Requirements of all relevant European directives and is eligible for CE marking.
The CE Declaration of Conformity can be obtained from: www.shure.com/europe/compliance
Authorized European representative:
Shure Europe GmbH
Headquarters Europe, Middle East & Africa
Department: EMEA Approval
75031 Eppingen, Germany
Phone: +49-7262-92 49 0
Fax: +49-7262-92 49 11 4