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222 HARTREY AVE • EVANSTON, ILL. (60204) U.S.A.
AREA CODE 312/328-9000 • CABLE SHUREMICRO
MODEL M62V AUDIO LEVEL CONTROLLER
DATA SHEET
MODEL M62V
AUDIO LEVEL CONTROLLER
GENERAL:
The “Level-Loc” Audio Level Controller is basically
a low noise preamplifier with unity gain from micro-
phone level in to microphone level out or 60 db of
voltage gain from Hi Imp. microphone level in to Aux.
Output. The input and microphone level output contain
matching transformers so either high or low impedance
may be selected. In addition, a high impedance Aux.
Output is provided capable of driving any high impedance amplifier, mixer or tape recorder input requiring 1 volt or less. This preamplifier has the additional capability of reducing its gain as the input
signal increases, thereby ho/ding the output signal
constant. After a predetermined input level is reached
(threshold) the output level is “Locked”, that is, it
remains constant even if the input signal increases
by as much as 100 times (40 db). This reduction in
gain, which results in a constant output level, is
obtained without introducing significant distortion or
transients into the program material. The DISTANCE
SELECTOR switch determines the input level at which
gain reduction (Level-Lot action) begins. An INPUT
LEVEL CONTROL is also provided that:
1.
Can be used as a vernier control to allow fine
adjustment of input threshold between the preset
threshold levels selected by the DISTANCE
SELECTOR switch.
2. Can act as an input attenuator for signals that
are higher than normal microphone levels. Such
inputs may be: signals from microphones used
very close to the mouth, outputs from preamplifiers, line amplifiers, tuners or tape recorders.
The Audio Level Controller: –
n Reduces blasting or large volume increases
when a speaker or entertainer varies his distance and position from the microphone.
n Upgrades tape-recording systems and the Audio
portion of Video Tape Recorders, by controlling
the maximum signal level being fed to the recorder. This prevents distortion and overloading
of the tape recorder which might be caused by
“close talking” the microphone, or by very loud
vocal or musical passages.
n Permits any number of microphones to be used
in a paging system or conference arrangement,
without setting the level for each individual
microphone. (For paging systems only low impedance microphones with normally open switches
should be used.) Any number of these microphones may be operated in parallel across the
low impedance input of the M62V, the Audio
Level Controller will automatically set a fixed
maximum paging level that cannot be exceeded.
SPECIFICATIONS
Input Impedance (below threshold):
High Impedance: 50 K ohms
Low Impedance: 300 ohms (for 25 to 600 ohm
Input Levels:
High Impedance: microphone level to 10 volts
Low Impedance: microphone level to .2 volt
Output Impedance:
High Impedance Microphone Level: 3.3 K ohms
Minimum recommended load: 5 K ohms
Low Impedance Microphone Level: Less than 50
ohms
Minimum recommended load: 25 ohms
Aux. Output: 10 K ohms.
Minimum recommended load: 10 K ohms
Gain Characteristics: [Below threshold, Input Level
control Maximum (10); measured from input to
output] :
INPUT
Hi Imp. Mic. Unity
Lo Imp. Mic.
Frequency Response:
± 2 db 40 to 20,000 Hz
sources)
max. (using input level control)
max. (using input level control)
OUTPUT
Hi Imp. Mic. Lo Imp. Mic. Aux. Output
+20 db
-20 db
Unity
+60 db
+80 db
Copyright 1969, Shure Brothers Inc.
27A823 (JI)
Printed in U.S.A.
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Maximum Output Noise (high-impedance microphone
output), in db below 1 volt:
300-20,000 Hz
(Noise)
30-20,000 Hz
(Hum and Noise)
Lo Imp. input
150 ohm Termination -103 db
-95 db
Hi Imp. Input
33 K ohm Termination -104 db
-95 db
Distortion (any level of regulation):
3% maximum THD.
Dynamic Characteristics:
Fast attack, moderate re-
covery, fixed.
Attack: For a 20 db step increase above threshold,
gain is within 2 db of final value in 500
microseconds.
Recovery: For a 20 db step decrease to threshold,
gain is within 2 db of final value in 700
milliseconds.
Battery Life: Approximately 200 hours.
Dimensions: See Figure 5.
Net Weight: 2.2 Ibs.
switch above the receptacle. This output is designed
to work into a 25 to 600 ohm microphone line or
microphone input, or into a high impedance amplifier
or tape recorder microphone input. The receptacle
is a male three-pin Cannon type XL-3-14 connector
(uses XL-3-11 mate, Shure Part No. 95A38, or XL-3-11 C
mate, Shure Part No. 95A176). See Figure 2b for
microphone level output receptacle connections.
MICROPHONE OUTPUT PLUG CONNECTIONS
FIGURE 2b
The receptacle marked AUX. OUTPUT is a phono
pin jack which accepts a standard phono pin plug.
This output is designed to work into a high-impedance
(10 K ohm or greater), high level input of a mixer,
preamplifier, amplifier, or tape recorder. This output
may be connected to the AUX. INPUT of an M68 Series
Mixer, the HIGH-LEVEL INPUT of an M63 Audio Master
or the line input (bridging) of an M67 Professional
Microphone Mixer.
The static characteristics of the high-level AUX.
OUTPUT are shown in Figure 1b. This output provides
a constant 1 volt level (with a 47 K ohm load) whenever the input level is above threshold. Below threshold it provides approximately 60 db of gain over the
Hi-Imp Mic. Level Input.
NOTE: This output is disabled when the MASTER
CONTROL switch is set to “Bypass.”
Input Connections: The Cannon-type receptacle
marked INPUT is designed for either low (25 to 600
ohms) or high impedance (50,000 ohms) inputs. The
impedance is selected by a slide switch above the
input receptacle. The unit is not recommended for use
with crystal or ceramic microphones.
The input receptacle is a female Cannon-type
XL-3-13 (uses XL-3-12 mate, Shure Part No. 95A55, or
XL-3-12C mate, Shure Part No. 95A227). See Figure
2a for low and high impedance connections to receptacle.
INPUT PLUG CONNECTIONS
FIGURE 2a
Output Connections: The receptacle marked MIC.
OUTPUT is a dual impedance output selected by the
Battery and Auxiliary Power Connections:
The battery to power the M62V is shipped with the
unit but must be installed. Install as follows:
1. Remove Battery Compartment Cover by removing
the lower slotted screw holding cover, loosening
the upper screw, and sliding the cover down.
2. Snap battery into clips provided.
3. Replace Battery Compartment Cover and tighten
screws securely.
Battery Replacement-Use Eveready type 216 or 222,
or equivalent 9 V. Battery.
AUX. INPUT POWER: This jack is used as a power
input when using the power supply of a Shure M67 or
M68 Series Mixer or M63 Audio Master.
case, the battery should be disconnected. A special
connecting cable is provided to connect the AUX.
INPUT POWER jack on the M62V to the Accessory
28 V. D.C. jack on the M68 Mixer or to the Pos. (red)
30 V. D.C. jack on the M67 Mixer or M63 Audio Master.
In order to utilize A.C. current, the use of a 9 volt
D.C. Battery Eliminator is suggested. There is a pro-
vision in the battery compartment cover that will allow
using a 9 V. D.C. Battery Eliminator to power the M62V.
The Battery Eliminator cable is to be slipped into the
split rubber grommet on the cover of the battery com-
partment. To secure cable, rotate grommet ½ turn.
Connection is to be made using the same battery
clips that normally connect to the 9 volt battery.
(Note: If a Shure M68, M67 or M63, or a Battery
Eliminator is to be used, first remove the battery.)
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In this
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CONTROLS AND OPERATION
MASTER CONTROL:
With the MASTER CONTROL in the “Bypass”
position:
The battery is disconnected from the “Level-Loc”
circuitry and thus the level-controlling action of
the M62V is inoperative.
The AUX. OUTPUT is disabled.
The input to the M62V is switched directly to the
MIC. LEVEL OUTPUT so in this “Bypass” condition the unit can serve as a microphone line
matching transformer.
With the MASTER CONTROL switch in the “Level-
Loc” position, the unit is energized, its level-con-
trolling capability operates, and the AUX. OUTPUT
is available.
DISTANCE SELECTOR:
When the M62V is being fed directly from a microphone source, best results are usually obtained when
the DISTANCE SELECTOR is set for the actual distance the performer is located from the microphone.
For example: a singer or soloist standing nominally 6
inches from a microphone would require a setting of
“6" or Less” on the DISTANCE SELECTOR. A panel
discussion where the speaker(s) may be any distance
up to 18 inches or more, would require a setting of
“18" or More” on the DISTANCE SELECTOR.
When recording in quiet surroundings, the 18"
setting of the DISTANCE SELECTOR may be used to
obtain maximum control of the recorded level. This
is especially advantageous in recording sound sources
where the volume is not predictable. If under these
conditions, very loud program material or high sensitivity microphones result in distortion, the DISTANCE
SELECTOR may be changed from the “18" or More”
position to the “12"” or “6" or Less” position. (Each
position represents a 6 db change in threshold.) In
extreme cases of overload the INPUT LEVEL CONTROL can be reduced (See INPUT LEVEL CONTROL)
When using the Audio Level Controller in a publicaddress system, with the Master Control in the “Level-
Loc” position, turn up the volume control on the
public-address amplifier to that point where the system
is just below the threshold of feedback with no one
speaking into the microphone. In this manner, the
total system gain is reduced as signal above threshold
is applied, and the system is more stable during loud
parts of the performance. Should accidental feedback
occur, the M62V will prevent it from becoming “ear-
splitting” or damaging the loudspeakers.
The Level-Lot action may be demonstrated by
switching from the LEVEL-LOC to the BYPASS position
of the MASTER CONTROL, provided the MIC. LEVEL
OUTPUT is being used.
Figure 1 illustrates the static input-output character-
istics of the Audio Level Controller, with the INPUT
LEVEL CONTROL at maximum and Hi Impedance input and Hi. Imp. microphone level output, (Note: there
is a 20 db level difference between Hi Imp. and Lo Imp.
A high impedance to low impedance transformer, as
used in the Input or Output of the M62V, gives a 20 db
reduction of voltage gain.)
As an example, consider the Distance Selector
switch set to the “18" or More” position. As the input
is increased from a low value, say -80 dbv (-80 dbv
means 80 db below 1 volt or .1 millivolt), the output
will increase as much as the input until point A, the
“threshold,” (the input level at which compression
takes place), is reached. Above this input level (-56
dbv), the output will remain nearly constant over an
input range of 40 db or more, as represented by curve
A-A’ (on Figure 1a).
The input threshold voltage, and consequently the
regulated output level, may be increased by either 6
or 12 db by changing the setting of the DISTANCE
SELECTOR. In this case, operation above the input
threshold is represented by curves B-B” or C-C’, according to the setting. These threshold voltages have
been chosen to approximate the output of a typical
microphone with an average speaker at the distances
labeled on the switch. At greater distances or quieter
speech, the output will follow the input, but if the
person speaking is louder or closer to the microphone,
the Audio Level Controller will prevent its output from
increasing, thus eliminating “blasting” or overloading
of subsequent electronics.
INPUT LEVEL CONTROL:
The INPUT LEVEL CONTROL is employed when a
higher-than-normal signal level is fed into the M62V,
such as the output of preamplifiers, line amplifiers,
tape recorders or tuners. The INPUT LEVEL CONTROL
may also be used as a vernier control to allow fine
adjustments of the input threshold that may occur
between the 6 db steps of the preset “DISTANCE
SELECTOR” switch.
High-impedance, unbalanced signals up to 10 volts
can be applied to the high-impedance input; low-
impedance, balanced signals no greater than 200
millivolts may be connected directly to the low-imped-
ance input. If the low-impedance signal is greater
than this (for example, a 600 ohm line at +4 dbm),
a line adapter balanced attenuator such as the Shure
A15LA may be connected between the line and the
input of the M62V. Alternately, if the line can be un-
balanced (one side grounded), it may be connected
to the high-impedance input with no attenuator.
With such inputs, the DISTANCE SELECTOR should
be set to the “6" or Less” position. To adjust the INPUT
LEVEL CONTROL, monitor the output of the M62V
and apply an average level input. Starting at 0, advance the INPUT LEVEL control. The signal will begin
to appear at the output and will increase in volume
until a point is reached at which no further increase
is noted. This is the threshold, and if the control is
left at this setting, any inputs less than the test input
level will pass through the M62V uncontrolled, while
those which are louder will be prevented from rising
and overloading succeeding equipment. Operation of
the Audio Level Controller above the constant output
region is not recommended. The curves shown on
Figure la and b are valid when the INPUT LEVEL
CONTROL is used; however, the appropriate attenuation must be added to the Input Voltage (Horizontal)
Scale. For example, if the INPUT LEVEL CONTROL
is set to “5” approximately 20 db should be added to
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the input voltage figures, so the point marked -60
dbv on the input voltage scale (Horizontal) would
become -40 dbv. In other words, the entire curve
would be shifted 20 db to the right.
TO USE WITH SHURE M68 SERIES MICROPHONE
MIXERS:
The two ways of using the M62V with the M68
Series Mixers are:
1. Connect a microphone directly into the Hi or Lo
impedance input of the M62V. Connect the
microphone level output of the M62V (Hi or Lo
impedance) to a microphone input on the M68
mixer (either Hi or Lo Impedance, whichever
was selected on the M62V). This method gives
audio “Level-Loc”
control on the one microphone attached to the M62V ONLY. All other
inputs to the M68 are unaffected.
2. Connect the M62V to control ALL inputs of the
M68 mixer, by connecting the microphone level
output of the M68 to the input of the M62V, (if
the Lo Imp. microphone level output of the M68
is used the M62V input must be set on LOW
Impedance, if the Hi Impedance microphone level
output of the M68 is used, the M62 input must
be set on Hi Impedance) or connect the Aux. Hi
level output of the M68 to the input (set on
Hi Imp.) of the M62V. (The INPUT LEVEL CONTROL may be used to control the threshold level
as covered under “INPUT LEVEL CONTROL.”)
The input for the main amplifier or tape recorder
is then connected to the M62V microphone level
output (Hi or Lo Imp.) or the AUX. OUTPUT.
When used in this manner, the MASTER CONTROL of the M68 Mixer should be set to about
“5” and the individual controls used to adjust the
proper blend between the channels. If more
overall volume is required, the volume control
on the main amplifier should be advanced. This
precaution will prevent equipment overload.
TO USE WITH SHURE M67 MICROPHONE MIXER:
Follow the instructions above for the M68, but only
the low-impedance input or output may be used when
connected to the M67. The setting of the M67 controls
only need be such that the VU meter indicates properly
to avoid overload.
TO USE WITH SHURE M63 AUDIO MASTER:
Follow the instructions above but only the AUX
OUTPUT of the M62V may be used to feed the Hi Level
input of the M63. The setting of the M63 Master Gain
control will control the overall system gain after the
Level-Loc.
OPERATION HINTS:
Remember that the M62V “Level-Loc” is a device
that provides a constant output level after a predeter-
mined input level is reached (threshold), therefore, if
more system gain is needed in PA applications or a
higher record level is desired in tape recording applications, DO NOT INCREASE THE INPUT LEVEL GOING
INTO THE “LEVEL-LOC;” once input threshold has
been reached the output level becomes fixed IT CAN
NOT GO ANY HIGHER. For more system gain, increase
the gain control of amplifier, preamplifier or tape recorder that is being fed from the M62V.
Note: For best results it is recommended that some
time be spent in experimentation with the
LEVEL-LOC to enable the user to become
accustomed to the advantages which this unit
presents.
Guarantee: The Shure Model M62V Audio Level Con-
troller is guaranteed to be free from electrical and
mechanical defects for a period of one year from date
of shipment from the factory, provided all instructions
are complied with fully. In case of damage, it is
essential that you carefully repack the unit and return
it to the factory, or, if outside the United States, to
your dealer or authorized Shure Service Center for
repairs. Our guarantee is voided if the basic assembly
has been opened other than to perform the modification described, or subjected to unreasonably rough
handling.
M62V Modification for
Non-disabling Aux. Output
The M62V may be rewired internally so that the Aux.
Output will operate (without Level-Lot action) when the
MASTER CONTROL is set to BYPASS, rather than
being disabled. This option is useful when the M62V
AUX. OUTPUT is connected to the auxiliary input of the
M63 Audio Master or M68 Series Mixers. Note: With
this option, the M62V power cannot be turned off by
the MASTER CONTROL switch. Power should be sup-
plied to the M62V from an external source such as the
Accessory 28 V. D.C. jack on the M68 Mixer or the
Pos. (red) 30 V. DC. jack on the M67 Mixer or M63
Audio Master, and the internal battery must be removed.
To make this modification (see Figures 3 and 4):
1.
Remove battery from unit.
2.
Remove cover from unit.
3.
Unsolder and remove wire between MASTER
CONTROL switch S3, terminal #8, and terminal
strip end of 10K ohm, ½ watt resistor.
4.
Unsolder wire from S3, terminal #7, and solder it
to terminal strip end of 10 K ohm, ½ watt resistor.
5.
Unsolder positive end of 2 mfd x 15 volt capacitor
from collector of Q3.
6.
Connect a wire from positive lead of 2 x 15 ca-
pacitor to S3, terminal #8.
7.
Connect a wire from collector of Q3 to S3, ter-
minal #7.
8.
Connect a wire from center terminal of INPUT
LEVEL control R1 to S3, terminal #9.
9.
Install a jumper wire between terminals #4 and
#5 of S3.
10.
Replace cover of unit, but do not install battery if
the M62V is to be powered from an external
source.
MASTER CONTROL SWITCH S3
TERMINAL DESIGNATIONS
(REAR VIEW)
FIGURE 3
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SCHEMATIC CHANGES FOR MODIFICATION
FIGURE 4
OVERALL DIMENSIONS
FIGURE 5
OPTIONAL ACCESSORIES
A68S Stacking Kit
The A68S Kit enables you to conveniently stack
together the M62V with the M63, M67 or M68 Series
Mixers. An interconnecting cable is provided for connecting the AUX. OUTPUT of the M62V to the M68
Series Mixers or an M63 Audio Master. Additional units
can be stacked with the use of additional A68S Kits.
The Stacking Kit includes two brackets and an interconnecting cable.
A68SC Interconnecting Cable
Cable only, as supplied in the A68S Stacking Kit,
for use in connecting the AUX OUTPUT of the M62V
to an M68 Series Mixer (Aux Input) or M63 Audio
Controller. The A68SC is a 12” long single conductor
shielded cable with a phono plug on each end.
A68L LOCKING PANEL
The A68L Panel fastens over the controls of the
M62V, M63, M67 or M68 Series Mixers, locks in place
with a padlock (supplied), and prevents tampering with
controls once they have been set. The A68L Kit contains locking panel, small padlock and two keys.
A68L LOCKING PANEL
A68R RACK PANEL KIT
Designed to mount M62V Audio Level Controller in
standard 19” rack.
Installation and Mounting
Assemble brackets to panel using hardware
supplied.
Remove two cover mounting screws from bottom
of M62V.
Slide M62V into brackets and re-assemble screws
through brackets into bottom of mixer.
NOTE: The A68L Locking Panel may be used
simultaneously with the A68R Rack Panel
Kit.
A68C OUTPUT CABLE KIT
The A68C Output Cable Kit provides a convenient
and flexible method of connecting the microphone
level output of the M62V, M63, M67 or M68 Series
Mixers to the great variety of amplifier and input receptacle configurations. Enables you to connect to
virtually any PA system. Kit includes:
l One 15’ two-conductor shielded cable with three
pin Cannon type XL-3-11 and XL-3-12 plugs.
l One 12” two-conductor shielded adapter cable
with Cannon XL-3-11 plug on one end and
Hubbel twist lock plug on other end.
l One 12” single conductor shielded adapter cable
Cannon type XL-3-11 on one end and Amphenol
type MC1 on the other end.
l One Phone Plug adapter for use with MC1 Con-
nector.
A68R RACK PANEL KIT
AC60 ATTACHÉ CARRYING CASE
The AC60 is a vinyl-covered attache type carrying
case (compartmentalized and foam lined), with space
for any of the M62V, M63, M67 or M68 Series Mixers
and as many as four microphones, cables, adapters,
and other accessories.
A68C OUTPUT CABLE KIT
AC60 ATTACHÉ CASE
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DESCRIPTION
2N5458
PARTS LIST
2N5088 OR T.I. 2N3711
GAIN, LOW NOISE. SIMILAR TO MOTOROLA
NPN TRANSISTOR, SILICON, SELECTED HIGH
86A327
SHURE PART NO.
ITEM
Q1-Q5, Q8
POTENTIOMETER, 50K, AUDIO TAPER
PNP TRANSISTOR, SILICON, T.I. TIS93
N-CHANNEL JUNCTION FIELD EFFECT
AUDIO TRANSFORMER AND SHIELD ASSEMBLY
SWITCH, SLIDE, D PDT
SWITCH, SLIDE, TPDT
TRANSISTOR, MOTOROLA 2N5458
86A329
86A335
46A021
55A54
90A1590
55A70
55A62 SWITCH, SLIDE, DPTT
R1
Q9
T1, T2
S1, S2
S3
S4
Q6, Q7
FIGURE 6
CIRCUIT DIAGRAM
MODEL M62V AUDIO LEVEL CONTROLLER
ELECTROLYTIC
ALL CAPACITORS IN MFD AND 100 VOLTS OR MORE
UNLESS OTHERWISE SHOWN.
CAPACITORS SHOWN IN MFD x VOLTS.
1.
NOTES :
ALL RESISTORS ± 10% TOLERANCE AND 1/4 WATT
UNLESS OTHERWISE SHOWN.
2.
CHASSIS GROUND CIRCUIT COMMON
THE FOLLOWING SYMBOLS DENOTE:
3.
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