Shure M267 User Manual
GENERAL
The Shure Model M267 is a microphone mixer-remote
amplifier specifically designed for professional applications.
The excellent performance, versatility and features of this
complete, compact console make it an ideal choice for studio, remote, or sound reinforcement use, and as an add-on
mixer for expanding existing facilities. It is also ideally suited
for use with audio and video tape recorders to provide multiple microphone inputs.
Features:
S Wide, flat frequency response and extremely low dis-
tortion up to +18 dBm output
S Extremely low noise and RF susceptibility
Four switchable microphone- or line-level balanced-line
S
inputs with individual gain controls and low-frequency
rolloff switches. MUMETAL shielding on input transformers
S Feedback-type input gain controls for maximum clip-
ping levels and dynamic range
S Output switchable for line or microphone level
S Built-in switchable peak limiter cuts output overload
distortion, adapts to power supply voltage
S LED indicator shows limiter operation or overload with
limiter defeated
S Externally adjustable limiter threshold (–4 to +18 dBm)
S VU meter calibrated for +4 and +8 dBm with range
switch. Illuminated with ac operation
S Ac or built-in battery operation. Noiseless automatic
switchover to battery in case of ac line failure. Battery
test without program interruption
S Front-panel headphone level control and monitor jack
drives almost any stereo or mono headphones; output
can be additional unbalanced line feed to drive a tape
recorder or power amplifier
Shure Brothers Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
Model M267 User Guide
S Direct mix bus for stacking units
S Automatic muting prevents speaker damage during
turn-on and -off
S Low distortion, high-stability tone oscillator for line test
and level checks
S All connections phased. Line output terminals phase-
indicated
S Compact and lightweight, with rugged, abrasion-resis-
tant case
S Internally selectable 120 or 240 V ac, 50/60 Hz opera-
tion
S Underwriters’ Laboratories Listed and Canadian Stan-
dards Association listed as Certified
SPECIFICATIONS
Frequency Response
30 Hz to 20,000 Hz, ±2 dB
Voltage Gain (at 1,000 Hz)
(Outputs terminated: line 600 W, microphone 150 W, mix
bus 3.3 kW, headphone 200
sleeve )
Input
Low-Impedance
Microphone (150
Line 40 dB –9 dB –27 dB
Mix Bus 55 dB 5 dB – –
Line Microphone Mix
91 dB 41 dB 24 dB
Ω)
Inputs
IMPEDANCE
Designed
Input
Microphone 19 to
Line Less
Mix Bus
∗Depending on input control setting
for Use
With
600 Ω
than10 kΩ
3.5 kΩ 3.5 kΩ
(Internal)
W, tip-sleeve and ring-
OUTPUT
Actual
1 kΩ
66 kΩ
Input
Clipping Level
–32 dBV to
–5 dBV∗
(25 mV to 0.56 V)
+20 dBV
+7 dBV (2.2 V)
Bus
E1999, Shure Brothers Incorporated
27A8376 (SE)
Printed in U.S.A.
Outputs
Headphone Output Clipping Level
IMPEDANCE
Designed for
Output
Microphone Any low imped-
Mix Bus
Headphones
Line
∗∗Depending on level control setting
Use With
ance microphone
input
3.5 kΩ 3.5 kΩ
8 - 2000 Ω
200 Ω
recommended
600Ω 150Ω
Actual
(Internal)
0.5 –34 dB
400 Ω to
3 kΩ∗∗
Clipping Level
(400 mV)
+18 dBm
Output
(2 0 mV)
–8 dBV
+10 dBV
(3.3 V)
(6.2 V)
Noise
Equivalent Input Hum and Noise: –126 dBV (low im-
pedance microphone, 150 Ω - 20-20,000 Hz) into a
600 Ω load at full gain
Output Noise: –75 dBV (master control fully counter clockwise), –53 dBV (master fully clockwise), (input controls down, 300-20,000 Hz)
Output Hum and Noise: –70 dBV (master control
down), –51 dBV (master control up) (input controls
down, 20-20,000 Hz)
3.16V (+10 dBV) into 200 Ω
Tone Oscillator
1,000 Hz, 1.5% or less THD
Phantom Power
30 Vdc open-circuit, 3.3 kΩ series resistance, input
switches in MIC position only
Operating Voltage
Ac Operation: 120 or 240 volts ±10%, 50/60 Hz,
9.5W, internally switchable[
Dc Operation: 27 volts nominal at 15 mA typical no-
signal, 18 mA typical at 0 VU (+4 dBm) output with
headphone load; 21.5 volts minimum
Battery life: approximately 20 hours with alkaline batteries at +4 dBm output in continuous use; three 9-volt
batteries, type NEDA 1604A (Duracell MN1604 recommended)
[ Supplied wired for 120 V ac operation (See Service section for 240
Vac operation)
Distortion
0.35% or less THD from 30 to 20,000 Hz at +15 dBm
output; 0.5% or less IM distortion up to +15 dBm output
level
Common Mode Rejection
65 dB minimum with input of –20 dBV at 100 Hz
Control Interaction
Less than 1 dB with any control combination
Overload and Shorting Protection
Shorting the outputs, even for prolonged periods, will
cause no damage; microphone inputs will not be damaged by signals up to 3 volts
Lo-Cut Filters
6 dB/octave rolloff at 150 Hz
Limiter
Threshold: +15 dBm (line output level; adjustable
from –4 to +18 dBm)
Attack Time: 3 msec typical
Recovery Time:500 msec typical
Temperature Range
Operating: –18o to 57o C (0o to 135o F)
o
Storage: –29
to 71oC (–20o to 160o F)
Dimensions
See Figure 1
309 mm
(12 5/
in.)
32
(2 23/32 in.)
FIGURE 1
Weight
Net: 2.3 kg (5 lb 2 oz)
Packaged: 3.2 kg (7 lb 2 oz)
Certifications
68.8mm
6.3 mm
(
1
/4 in. )
229 mm
(9 in.)
Peak Indicator
Lights 6 dB below clipping or at onset of limiter action
Listed by Underwriters’ Laboratories, Inc., and listed by
Canadian Standards Association as Certified
2
CONTROLS AND CONNECTORS
WARNING
This apparatus must be earthed (grounded)! The
M267 power supply is energized when the unit is
connected to an ac source; disconnect mains
(power) plug from supply when not in use.
Input control 1 serves an additional function as the level
control for the tone oscillator when the INPUT 1/OCS 1
switch is in the OSC 1 position.
IMPORT ANT: For optimum signal-to-noise ratio, the individual input controls should be operated at as high a setting as possible, consistent with maintaining adequate
control range and input clipping level.
Master Gain Control
Inputs
The four inputs are professional three-pin female XLR
audio connectors located on the rear panel and designated
INPUT 1 through INPUT 4. The inputs are balanced (internal transformer, MUMETAL shielded); pins 2 and 3 are
“hot”, and pin 1 is “ground”. For microphone operation, the
switches labeled LINE/MIC (directly above the input connectors) must be in the MIC position; for line level inputs,
the switches must be in the LINE position. For impedance,
clipping and operating signal levels, refer to the SPECIFICATIONS section.
Outputs
The rear-panel connector labeled OUTPUT is a professional three-pin male XLR audio connector. With the adjacent LINE/MIC switch in the MIC position, the OUTPUT
connector is used to feed a low-impedance microphone
line or a low-impedance microphone input. With the LINE/
MIC switch in the LINE position, the OUTPUT connector
feeds the line-level input of an amplifier, tape recorder, or
another mixer. The OUTPUT connector is a balanced output with the LINE/MIC switch in either position; pin 1 is
ground, pins 2 and 3 are “hot”, and the connector is in
phase with the corresponding pins of the input connectors.
The rear-panel binding-post connector designated LINE
OUTPUT is in parallel with the OUTPUT connector and
can be used as a line-level output feed simultaneously with
the OUTPUT connector. The terminals are numbered 2
and 3 and are in phase with the corresponding pins of the
input connectors. While the line outputs can be used to
drive various impedance lines, the VU meter is calibrated
for use with a 600 Ω line.
The line output transformer will operate properly with up
to 100 mA dc in the line. This feature permits the use of
standard “dialed-up” telephone lines with dc across them.
(Since a slight distortion increase may occur at high output
levels with maximum dc current, operation with the VU
RANGE switch at +4 dBm is recommended.)
Input Gain Controls
The front-panel control designated MASTER is the master gain control which sets the overall output level of the
mixed sources (including signals applied to the MIX BUS
input).
Limiter
The front-panel LIMITER IN/OUT switch turns on a fastacting, peak-responding limiter circuit that cuts overload
distortion during loud program intervals without affecting
normal program levels. When the LIMITER switch is IN
(operating), the mixer output is limited to approximately
+15dBm. Increasing the individual or MASTER gain controls will increase the average output and the amount of
limiting. The limiter threshold can be reset to any other output between –4 and +18 dBm if desired. With the limiter
switched OUT and tone oscillator activated, adjust INPUT
1 and MASTER level controls to produce an output 0.5 dB
higher than desired. Switch the limiter IN and set the LIMITER THRESHOLD ADJUST control (accessible though
the bottom of the chassis) for the desired level.
The front-panel PEAK LED indicator shows limiter operation with the limiter in, and operates when program levels approach overload with the limiter out. The indicator is
much faster than a meter and will be activated by the shortest transient peak, but it remains on long enough to provide
easy recognition.
Low-Cut Filters
The low-cut filters provide a low-frequency rolloff to the
response curve as shown in Figure 2. The filters are activated by the LO-CUT IN/OUT switch above each individual
input gain control and can be used individually with each
control to reduce wind noise or undesirable low-frequency
signals such as from condenser microphones or turntable
rumble.
0
The front-panel controls designated 1 through 4 are the individual active gain controls for correspondingly numbered
inputs. Note that the input connectors are located on the rear
panel directly behind their corresponding gain control. The
controls set the preamplifier gain and provide preamplifier
output attenuation. As the gain is reduced, the preamplifier
input clipping level is increased for that channel.
–10
–20
20
100
200
500
1,00050
LOW-CUT FILTER ACTION
FIGURE 2
3
Loading...