Shure A68L, AC68, A68C, A68SC, A68P User Manual

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OPTIONAL ACCESSORIES

Battery Power Supply Output Cable Kit Locking Panel Phono Preamp Rack Panel Kit Stacking Kit Interconnecting Cable Attach6 Case

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Model A68B Model A68C Model A68L Model A68P Model A68R Model A68S Model A68SC Model AC68

SPECIFICATIONS

Gain: At 1,000

Input Mic.

Low Imp. Mic.

.5 mv produces 1.4 mv 22 mv 500 mv

High Imp. Mic. -13 db

5 mv produces 1.1 mv 18 mv 400 mv

AUX. -35 db -11 db f16 db

50 mv produces

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Frequency Response: The frequency response is flat &f:b from to 20,000 Hz. (cps)

Hum-Noise:

Equivalent Input Noise: 150 ohm source, 123 db below 1 volt. Input Impedance: Microphone inputs suitable for high

and ribbon microphones. Auxiliary-50,000 ohms.

Recommended Load Impedance:

Low Impedance Microphone High Impedance Microphone Auxiliary High Impedance

Distortion: Less than 1 phone output is at 20 mv level, high impedance microphone output is at 200 mv

level, and Output Clipping Level:

Operating Voltage

Models M68-2 and M68-2E: 105-130 volts 50/60 cycle or 210-240 volts 50/60

Aus.

output Min. Clipping Level Mic. Low Impd. Mic. High Impd. .85 volts Aux. High Impd.

Model M68: 105-130 volts 50/60 cycle

cycle. Case: Painted Metal. Dimensions: See Figure B. Net Weight: 4 pounds.

27A477

1-67)

1967,

Hz.

(cps).

Low Imp.

db +33 db +60 db

0.9

mv 14 mv 320 mv

db below rated output.

high impedance output is at 2.0 volt level.

Shure

Brothers,

--$32

aPPnoxU

5mm)

OVER

ALL

DIMENSIONS

.................................................

................................................

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total Harmonic Distortion when low impedance micro-

4.0

volts

Inc.

outputs

High Imp. High Imp.

Mic. Aux.

fll

db 4-38 db

ii3f8

12889mml-I

FIGURE

low impedance dynamic

25 to 600 ohms 20,000 ohms or greater 50,000 ohms or greater

,30

Hz. (cps)

fLO

222

MODELS

M68,

M68-2,

HARTREY

AREA CODE

AM)

M68-2E MICROPHONE MIXERS

AVE

EVANSTON,

312/328-9000 ' CABLE SHUREMICRO

ILL.

(60204)

U.S.A.

General: The Shure Models M68, M68-2, and M68-2E are five channel, completely transistorized, portable microphone mixers for use with public address systems and tape recorders.

The Mixers Feature:

Four microphone inputs with individual slide switches mounted on rear panel for selection of low impedance (balanced or unbalanced) or high impedance

(unbalanced).

One high level auxiliary input suitable for tape, tuner, and accessories.

Individual volume control to balance each of the five inputs.

A master volume control to simultaneously control level

A high (unbalanced) level output. Impedance selected with slide switch to match the microphone input of associated amplifier.

A high impedance auxiliary output.

low impedance (balanced or unbalanced) microphone

all inputs.

A DC power supply jack. This jack supplies 28 volts DC for use with accessories such

in connection with the Model A68B Battery Power Supply (Accessory).

the Model A68P Phono Preamplifier

A facility microphone inputs.

for

connecting two or more mixers together to obtain additional

For

example, two mixers connected together will give a total

it may be used

power input

of eight microphone inputs and one auxiliary input.

U.S.

Underwriters Laboratory approval for use in commercial applications.

(Applies to Model M68 and M68-2).

INSTALLATION

CONNECTION BETWEEN COMPONENTS

For balanced-line connection use two conductor, shielded, low capacity cable connections. For unbalanced (high impedance), use single conductor, shielded, low capacity cable for connections.

for

*'?

GROUNDING

If there should be objectional hum, ground the metal chassis of the mixer to a

good ground such as a metal frame of a wall outlet or a water or steam pipe.

INPUT CONNECTIONS

Microphones: A maximum of four low or high impedance dynamic or ribbon microphones may be connected to receptacles marked MIC.

MIC. 2, MIC.

MIC

The inputs are designed for low impedance microphones with 25 to 250 ohms impedance or high impedance microphones. Both low impedance and high impedance microphones may be used simultaneously with the M68. The unit is

not

recommended for use with crystal or ceramic microphones. The impedance is selected by a slide switch above the input receptacle. The input receptacle is a male Cannon

XLR-3-14 type (uses XLR-3-11C mate, Shure Part 95A-3176).

low and high impedance connections to receptacle.

Auxiliary: output from a high impedance, high level source such as a tape recorder, AM-FM

The jack on

the rear of the panel marked AUX. INPUT will accept

See Figure “A” for

tuner, or output from the Model A68P Phono Cartridge Preamplifier (Accessory).

OUTPUT CONNECTIONS

Microphone: The receptacle marked MIC. OUTPUT is a dual impedance out-

put selected by the switch above the receptacle. This output is the “Mixed”

output of all the input sources and is designed to work into

to 600-ohm line or input, or into a high impedance amplifier or tape recorder microphone input. The receptacle

“A”

for output receptacle connections.

a male three-pin Cannon XLR-3-14 type connector.

See Figure

Auxiliary: The phono jack marked AUX. HIGH LEVEL OUTPUT is a high impedance high level output designed primarily to feed a power amplifier requiring

2 volts or the auxiliary or tuner input to an amplifier or tape recorder.

28-volt

Accessory

DC: This rear panel jack provides 28 volts DC for accessories such as the Model A68P Phono Cartridge Preamplifier. The jack is also used as a power input when using the Model A68B Battery Power Supply (Accessory).

OPERATION

Power:

outlet. See Operating Voltage under Specifications. (All Mixers except the M68-2E

come with a standard two-conductor AC plug attached). The Model M68-2E is supplied with a three-conductor power line cord, but no plug.

The power line cord

black

terminals. The

the ground or earth terminal of the plug.

should be installed by qualified service personnel.

In the Models M68-2 and M68-2E, either operating voltage is selected by a switch on the back panel. A switch lock plate is provided to prevent accidental switching to the 105-130-volt position. These microphone mixers are shipped with operating voltage selector switch locked in the 210-240-volt position. The lock plate can be removed from the locking position by loosening (do not remove) the screw holding

the lock plate, rotating the lock plate ON-OFF switch is

CAUTION:

Volume Controls: The Master Gain Control and the individual gain controls for each of the five channels are identified

Connect the Microphone Mixer power line cord to the proper A.C. power

plug

should be installed by a qualified person. The

leads of the power line cord should be connected to the “hot” or line voltage

green

lead is the grounding conductor and should be connected to

different power line cord

the front panel.

Not Plug Power Line Cord of Models M68-2 or M68-2E into

plug

is required on the Model M68-2 Mixer, this plug

go”,

and re-tightening the screw. The power

210-240 volts when switched to 105-130 volts.

the front panel.

red

and

The individual gain controls should generally be set near maximum (fully clockwise) and the master gain control adjusted to required output. Individual channel gain controls not being used should be kept at minimum gain (fully counterclockwise).

Identifying Controls

Pressure sensitive adhesive labels are supplied with the Mixers as a means of identifying the control and recording the control position when optimum results have been obtained. The labels are easily removed when their

longer required.

CONNECTING

TWO

UNITS TOGETHER

use

Two M68 Mixers may be combined to give a total of eight microphone channels

plus an auxiliary input. A. Connect the AUX. HIGH LEVEL OUTPUT of UNIT

to the AUX. INPUT

OF UNIT 2.

Connect microphones

position.

Take the output signal for recorder or P.A. amplifier from the appropriate

to mixers and set each microphone input control to

output jack on UNIT 2.

Set Master Control UNIT 1 to position

#lo.

E. Set AUX. Control on UNIT 2 to position #4.

The Master Control on UNIT 2 is now the Master for all inputs.

Advance Master Control (UNIT 2) to about #5 position and adjust individual microphone controls for proper level. Master Control (UNIT

an input to the auxiliary channel is needed, such as for a tape recorder

or tuner,

use

AUX. input on UNIT 1. Use AUX. Control

may be adjusted.

overall gain is too low or too high the

UNIT 1 for level adjustment of the AUX. source. The master gain control for the entire system is the Master Control

UNIT 2.

The Model A68S Stacking Kit includes stacking brackets for attaching the two

mixers firmly together plus the required inter-connecting cable. The cable only, is

available separately under the Model A68SC.

Guarantee: The Shure Model M68 Mixer 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 daamge, it is essential that you carefully repack the unit and return it to the factory or, if outside

the United States,

your dealer or authorized Shure Service Center for repair. Our guarantee is voided if the basic assembly has been opened or subjected to unreasonably rough handling.

SHIELD

MICROPHONE

-____-

[BALANCED LOW IMPEDANCE LINE1

MIC. OUTPUT MIC. OUTPUT

MICROPHONE OUTPUT PLUG CONNECTIONS

MICROPHONE

MIXER INPUT MICROPHONE MIXER INPUT

MICROPHONE INPUT CONNECTIONS

HIGH IMPEDANCE

CONNECTIONS - FIGURE

HIGH IMPEDANCE

-_____

LOW IMPEDANCE

(BALANCED LINE1