Shure M677 Schematic
222
HARTREY AVE.. EVANSTON, IL.
Q
AREA
CODE
TWX:
312/866-2200
910-231-0048
60204
U.S.A.
.
CABLE: SHUREMICRO
TELEX:
72-4381
I
:iEtT
MODEL M677
ACCESSORY MIXER
I
GENERAL
The Shure Model M677 is a transistorized, six-input
accessory mixer designed for use with such products
as the Shure M67 and M68 Series Microphone Mixers,
SE30 Gated
Compressor/Mixer, and M63 AUDIO
MASTER@. When used with either the M67 or M68, it
provides a low-cost and convenient means of adding
six additional input channels (10 total). When used
with the
SE30, it converts the three-input mixer system
to a nine-input system for applications such as tele-
vision broadcasting. For instance, when used with the
M63, the combination provides a six-channel mixer
with extremely flexible equalization, a 600-ohm line
output, a VU meter, and a headphone monitor.
The M677 is designed to connect to and operate
from the 28-30 Vdc output of the Shure mixer product
with which it will be used, or from the Shure
A67B
Battery Power Supply. When this external power supply is used, the M677's high- or low-impedance micro-
phone-level output allows it to be used with virtually
any audio equipment having a microphone input (audio
tape recorder, video recorder, PA system, etc.).
M677
Model
H
Adds extra inputs to Shure mixers
H
Six balanced input channels
H
Switch-selectable inputs: low impedance micro-
Features:
phone- or line-level
H
Professional three-pin input connectors
H
Microphone output with professional three-pin connector and high-low impedance selection
H
Connects to mix bus or aux input on associated
mixer
H
Six individual rotary input volume controls
H
Switchable lo-cut filters on each channel
H
Obtains power from associated Shure mixer or
battery power supply
SPECIFICATIONS
Inputs
NO. LEVEL IMPEDANCE CONNECTOR
LO-Z
MIC/LINE
Switch Selected High (LINE) female*
Outputs
NO. LEVEL IMPEDANCE CONNECTOR
MIC
MIX BUS or
AUX High phono jack
*Designed to mate with Cannon XL Series, Switchcraft A3
or equivalent connector
Low (MIC) 3-pin professional
High/Low 3-pin professional
male*
(Q.G.)
Series
Voltage Gain (at 1,000 Hz)*
*
OUTPUT
LOW IMP. HIGH IMP. AUX MIX
INPUT
MIC
LINE
"Microphone inputs through 150 ohms, line inputs through 600 ohms,
LO-CUT switches in FLAT position, Lo-Z microphone output terminated
In 150 ohms, Hi-Z microphone output terminated in 33 kilohms, MIX
BUS AND AUX OUTPUT terminated in 47 kilohms, all volume controls
full up.
t47
tt3.5 kilohm load on MIX BUS AND AUX OUTPUT
MIC. MIC. OUTPUTt BUSti
-3
-53.5 dB -29 dB
kllohm load on
dB
t21.5 dB
MIX
BUS AND AUX OUTPUT.
+
-12 dB -30 dB
--
38.5 dB +20.5 dB
Frequency Response
Flat
-t2 dB from 30 Hz to 20.000 Hz
Equivalent lnput Noise
At full gain, -128
dBV, 300 to 20,000 Hz noise
bandwidth, measured at MIX BUS AND AUX OUTPUT
Equivalent lnput Hum and Noise
At full gain, -125
dBV, 30 to 20,000 Hz noise
bandwidth, measured at MIX BUS AND AUX OUTPUT
Maximum Output Hum and Noise
MIX BUS AND AUX
OUTPUT
(all controls min.)
MIX BUS AND AUX
OUTPUT
(all controls max.)
Noise Hum & Noise
(300-20,000
-95
-84
Hz)
dBV
dBV
--
(20-20,000
-92
dBV
-81
dBV
Hz)
Impedance
INPUT DESIGNED FOR USE
MIC Input Balanced or unbalanced 25 to 800 ohms typical
LINE Input 33 kilohms or less Line or Aux 66 kilohms typical
OUTPUT DESIGNED FOR USE
Low Imp. MIC Balanced or unbalanced 25 to
High Imp. MIC Unbalanced to 50 kilohm micro-
MIX BUS AND 3.5 kilohm mix bus
AUX OUTPUT high
600 ohm microphones
600-ohm microphone level circuits
phone level circuits
~mpedance aux input (up to
50K) (single output with dual
function)
WITH IMPEDANCE
WITH IMPEDANCE
or
unbalanced 40 kilohms typical
ACTUAL
ACTUAL
40 ohms typical
4.3 kilohms typical
Copyright 1979, Shure Brothers Inc.
27AlO8l (SJ)
Printed in.U.S.A.
Distortion
Less than 1 % Total Harmonic Distortion at 1,000 Hz
when Low lmpedance Microphone Output is at 20
level, High lmpedance Microphone Output is at
300
mV level, and MIX BUS AND AUX OUTPUT is
at 2V level (loaded with 47 kilohms).
lnput Clipping Level
Minimum Clipping Level
Low lmpedance
Microphone
Line Input lOV (+20 dBV)
Input
25
mV
(-32 dBV)
Minimum Common Mode Rejection
110 dB with microphone input of 10V at 100 Hz
Output Clipping Level
Minimum Clipping Level
Low lmpedance
Microphone Output
High Impedance
Microphone Output
Mix Bus and 0.4V
Aux Output
25
mV (-32 dBV)
0.4V
(-
8 dBV)
( - 8 dBV) (3.5K load)
3V
(+
10 dBV) (47K load)
Phase
The Mix Bus and Aux, and Microphone Level (High
Impedance) Outputs are in phase with pin 3 of each
input connector. The Microphone Level (Low Imped-
ance) Output is in phase with each input.
Lo-Cut Filters
-6 dB at 100
Hz
typical
Volume Controls
All audio taper
Operating Voltage
27 Vdc, 6.0 t2 mA. (Meets all specifications except
clipping levels at any voltage from 20 to 34 Vdc)
Temperature Range
Operating: -7" to 57°C (20" to 135°F)
Storage: -29" to 71
"C (-20" to 160°F)
Dimensions
See Figure 1
mV
INSTALLATION AND OPERATION
INPUTS
A maximum of six low-impedance dynamic, ribbon
or condenser (capacitor) microphones may be connected to receptacles marked INPUT 1 through INPUT
6. With
accept signals from the above microphones or
phone-level signals such as the low-impedance
microphone-level outputs of mixers. With
switches set to LINE, the inputs will accept balanced
600-ohm line-level signals.
30
supply 20 to 34 Vdc (6.0
sociated Shure mixer to power the M677. In addition,
the M677 may be powered from a Shure
power supply. NOTE: For use with Shure M68 Series
Mixers, connect only the red 30 VDC cable to the M68;
ground connection is provided through the phono or
microphone cable.
CAUTION: If the
power cables should be insulated to avoid accidental
shorting or grounding.
MICILINE switches set to MIC, the inputs will
VDC:
The attached cables and rear-panel jacks
mA at 27 Vdc) from an as-
A67B battery
A678 is used, the M677's attached
micro-
MICILINE
OUTPUTS
MIC OUTPUTS:
has either low- or high-impedance microphone-level
output selected by the switch above the receptacle.
This output is designed for connection to a 25 to 600
ohm microphone input or to a high-impedance microphone input of an amplifier or tape recorder. (This
output may be used simultaneously with the MIX BUS
AND AUX OUTPUT connector.) See section on
CONNECTIONS for instructions on connection to a
high- or low-impedance balanced or unbalanced line.
MIX BUS AND AUX OUTPUT:
that both mix bus and aux output functions are fed
through the same connector. The unusual circuit
design associated with this output enables it to be
connected to a mixer, tape recorder or amplifier aux
input (47 kilohms) or a Shure mixer mix bus (3.5
kilohms). This connector cannot be used to drive
a mix bus and aux input at the same time, because
connection to a mix bus (about 3.5
the signal at this connector to a level which is too low
for most aux inputs. Note that when connected to an
AUX input, the MIX BUS AND AUX OUTPUT connector
cable should be 3m (10 ft) maximum; when connected
to a mix bus input, the cable may be up to
For mix bus connections such as stacking several
M677's, this jack may be used with the supplied phono
pin connector cable and a
to be used to drive more than one input, a
should also be used. See section on
for instructions on connection to mating phono plug.
30
VDC:
as output jacks to provide power to an additional M677
(as well as input jacks from an external battery sup-
ply) when the M677 is powered through the 30 VDC
attached cable connectors.
The receptacle marked MIC OUTPUT
It is important to note
both
kilohms) will reduce
30m (100 ft).
"Y"
adapter. If this jack
"Y"
is
adapter
CONNECTIONS
The rear-panel 30 VDC jacks may be used
Net Weight
1.7 kg (3% lb)
OVERALL
FIGURE
DIMENSIONS
1
CONNECTIONS
The microphone inputs and output are three-pin
professional connectors (designed to mate with Cannon
XL series, Switchcraft A3
A mating three-pin professional male connector (to
(Q.G.)
series or equivalent).
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