Shure SCM268 Specification Sheet

SCM268 Microphone Mixer

Specification Sheet

SCM268 TRANSFORMER BALANCED MICROPHONE MIXER

The Shure Model SCM268 is a transformer-balanced, four-channel microphone mixer. Its simple, compact design delivers superior performance

and exceptional sound quality with low noise and a flat frequency response.

Versatile in all types of applications, the SCM268 integrates transformer-balanced XLR inputs, a switchable microphone/line level transformer-bal­anced XLR output, phono jack inputs and output, phantom power, and an auxiliary input channel. It can function as a primary or add-on mixer for
sound reinforcement, recording, broadcast, or audio-visual presentation systems.

With the supplied hardware, the mixer's half-rack chassis mounts securely in single or dual rackmount installations. For fixed installations, the
SCM268 can be fastened on or below a shelf, counter, or tabletop.

SYSTEM FEATURES

• Four transformer-balanced microphone inputs

• Transformer-balanced output-switchable mic/line level

• Five –10 dB line-level inputs

• Six-segment LED output level meter

SPECIFICATIONS

Measurement Conditions (unless otherwise specified): Line voltage 120
Vac, 60 Hz (SCM268) or 230 Vac, 50 Hz (SCM268E); full gain; 1 kHz,
one channel activated; source impedances: Mic 150 Ω, Aux Level 150
Ω; terminations: Line 600 Ω, Mic 600 Ω, Aux Out 10 kΩ. 12 V phantom
power off.

Frequency Response (Ref 1 kHz, controls centered)

Microphone Inputs: 150 Hz to 20 Khz + 2 dB (built-in 80 Hz low-cut)
Auxiliary Inputs: 20 Hz to 20 kHz + 2 dB

Low-Cut Filter (Microphone inputs only)

3dB down at 80 Hz, 6 dB/octave

Gain (typical, controls full clockwise)

Input Output

Mic Line Aux Out

Low-impedance mic
(150 Ω)

Aux Level 3 dB 40 dB 29 dB

Inputs

Input Impedance

Mic 19-600 Ω 1.2 kΩ –5 dBV

Aux Level 32 kΩ 21 kΩ >28 dBV

38 dB 76 dB 65 dB

Designed for
use with

Actual
(typical)

Input
Clipping Level

• Built-in 12-volt phantom power

• Internal power transformer

• Built-in low-cut filter on microphone inputs (below 80 Hz)

Outputs

Output Impedance

Designed for
use with

Mic low-Z inputs 0.2 Ω –21 dBV

Line >600 Ω 72 Ω +18 dBV

Aux Out >2 kΩ 870 Ω +7 dBV

Actual
(typical)

Output Clipping
Level

Total Harmonic Distortion

<0.25% at +4 dBu output level (through 22 Hz–22 kHz filter; Input
1 and Master centered, all other controls full counter clockwise)

Hum and Noise (150 Ω source; through 22 Hz–22 kHz filter)

Equivalent Input Hum and Noise: –124 dBV

Output Hum and Noise (through 22 Hz–22 kHz filter; channel con­trols full counterclockwise)

Master full counterclockwise: –92 dBV
Master full clockwise: –70 dBV

Common Mode Rejection

>80 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;
Auxiliary inputs by signals up to +36 dBV

TL1028 (CB)
©2008 Shure Incorporate d

SCM268 MICROPHONE MIXER SPECIFICATION SHEET

Phantom Power

12 Vdc open-circuit through 340Ω series resistance

Operating Voltage

SCM268: 100-120 Vac rated nominal, 50/60 Hz, 60 mA

SCM268E: 220-240 Vac rated nominal, 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

44 mm H x 218 mm W x 162 mm D
(1.72 x 8.60 x 6.37 inches)

Net Weight

1.20 Kg (2 lbs, 10 oz)

Certifications

SCM268: UL & cUL Listed by Underwriters Laboratories, Inc.
SCM268E: Eligible to bear CE Marking. Conforms to European
EMC Directive 89/336/EEC. Meets applicable tests and perfor­mance criteria in European Standard EN55103 (1996) parts 1
and 2, for residential (E1) and light industrial (E2) environments.

REPLACEMENT PARTS

Knob, Master (blue)......................................................95B8752

Knob, Channel Gain (white) .........................................95A8752

Line (Power) Cords:

SCM268: 100-120 Vac (US/Canada).....................95A8762

SCM268E: 220-240 Vac (EU)................................ 95A8778

Fuse, SCM268 (5x20 mm, 250V, 80mA, slow-blow)......80A730

Fuse, SCM268E (5x20 mm, 250V, 40mA, slow-blow).... 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

Line (Power) Cord, 230-240 Vac (UK)..........................95A8713

SHURE Incorporated Web Address: http:// www.shure.com
5800 W. Touhy Avenue, Niles, IL 60714-4608, U.S.A.
Phone: [phone] Fax: [phone]
In Europe, Phone: [phone] Fax: [phone]
In Asia, Phone: [phone] Fax: [phone]
Elsewhere, Phone: [phone] Fax: [phone]