Shure M68P Schematic

222

HARTREY

MICROPHONES AN0 ELECTRONIC COMPONENTS

AREACODE312/3289000 CABLE SHUREMICRO

AVE . EVANSTON,

60204 U S

:/ET

MODEL M68P

MICROPHONE MIXER

The Shure Model M68P is a five-channel, completely transistorized, portable microphone mixer for use with sound reinforcement, tape recording and audio-visual systems.

The Mixer features:

A high-impedance (unbalanced) microphone level output.

Four microphone inputs for high-impedance (unbalanced) microphones.

One high-level auxiliary input suitable for tape, tuner, and accessories such as the Preamplifier.

Individual volume controls to balance each of the

five inputs.

A master volume control to simultaneously control level of all inputs.

A low-impedance (balanced or unbalanced) rnicrophone level output. A high-impedance, high-level auxiliary output. A dc power supply jack. This jack supplies 28 volts dc for use with accessories such as the

Model Loc or it may be used as power input in connec-

tion with the Model

(Accessory). A facilitv for connectina two or more mixers together

For example, two mixers connected together will

give a total of eight microphone inputs and one

auxiliary input.

Listing by Underwriters' Laboratories Inc. and

listing by Canadian Standards Association as

certified.

A68P Phono Preamplifier or M62V Level-

io obtain addithnal microphone inputs.

GENERAL

A67B Battery Power Supply

SPECIFICATIONS

Gain

At 1,000

Microphone

Auxiliary

Frequency Response

Flat within +3 dB from 40

Hum and Noise

70 dB below rated output (Aux. Output)

Equivalent lnput Noise

33 kilohm source, 103 dB below 1 volt

Impedance

INPUT

Microphone Unbalanced 10 to 50 60 kilohms Auxiliary 100 ohm to 10

INPUT

mV produces mV produces

DESIGNED

kilohm microphones unbalanced high-level

sources

1972,

Shure Brotherj Inc.

(NG)

OUTPUTS

Mic.

FOR

USE

kilohm 40-70 kilohms*

to 20,000

WITH

Mic.

ACTUAL

A68P Phono

IMPEDANCE

--;

OUTPUT

Low Imp.

Imp. Mic. Unbalanced 10 to 50 30-40 kilohms*

High

Auxiliary Unbalanced high-imped- 2.5-3 kilohms*

Depending upon control settings

Distortion

Less than 1% total harmonic distortion when lowimpedance microphone output is at 20 mV level, high-impedance microphone output is at 200 level, and auxiliary output is at 2.0 volt level.

Phase

All microphone inputs and outputs are in phase. Auxiliary input and output are out of phase with the microphone inputs and outputs.

Clipping Levels, Minimum

Microphone 450 mV

Microphone, High Imp. 850 mV Microphone, Low Imp. 60 rnV Auxiliary

Operating Voltage

108-132 volts, 50160 Hz, 3 watts

D.C. Operation

28 volts dc a20%, 5 mA

Dimensions

See Figure

Net Weight

1.25 kg (2% Ib)

Connection Between Mixer and Components

For balanced-line microphone level output connec-

tion, use two-conductor, low capacity shielded cable.

For unbalanced (high-impedance) microphone level or auxiliary high-level output connection, use single-conductor, low capacity shielded cable.

DESIGNED

Mic.

Balanced or unbalanced 150-300 ohms*

25 to

microphone-level circuits kilohm microphone-level

circuits

ance (10 kilohms or greater) auxiliary circuits

Input Clipping Level

Output Clipping Level

600

FOR

ohm

USE

WITH

ACTUAL

volts

Overall

Dimensions

FIGURE

INSTALLATION

:;;;";,

Printed in U.S.A.

IMPEDANCE

rnV

Grounding

If there should be objectionable hum, connect 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. This is normally accomplished automatically through the ground wire of the power cord.

INPUT CONNECTIONS

Microphones:

A maximum of four high-impedance dynamic, ribbon, or condenser microphones may be connected to the standard

MIC.

MIC. 2, MIC. 3, MIC. 4. The microphone inputs

Y4"

phone jacks marked

may be converted for use with low-impedance microphones by utilizing accessory plug-in transformers Model A95 Series. The unit is not recommended for use with crystal or ceramic microphones.

NOTE:

Some condenser microphones produce very high output signals which may overload the input of a mixer.

Auxiliary:

marked AUX. INPUT will accept output from a

The phono jack on the rear of the panel

highimpedance, high-level source such as a tape recorder, AM-FM tuner, or output from the Model

Preamplifier (accessory). The Model

A68P Phono

A68M Microphone

Preamplifier (accessory) may be connected to this

jack to provide a fifth microphone input.

OUTPUT CONNECTIONS

Low lmpedance Microphone:

The receptacle marked LO IMP. MIC. OUTPUT is a low-impedance microphone level output. This output is the "mixed" output of all the input sources and is designed to work into a 25 to 600-ohm microphone line or into a

low-impedance amplifier or tape recorder microphone input. The receptacle is a professional three-pin audio connector (male).? See Figure B for output receptacle connec-

tions.

SLEEVE

TIP

MIC.

OUTPUT

High lmpedance Microphone:

SHIELD

-----

\-----

HIGH

IMPEDANCE

Microphone Output Connections

FIGURE

MIC.

OUTPUT

._-_--

LOW

IMPEDANCE

(BALANCED

LINE)

The phone jack marked

HI IMP. MIC. OUTPUT is a high-impedance microphone

level output. This output is, also, the "mixed" output

of all sources, designed to work into

high-impedance

amplifier or tape recorder microphone input. See

Figure B for output jack connections.

NOTE:

The high- and low-impedance microphone out-

puts may be used simultaneously.

Auxiliary:

The phono jack marked AUX. OUTPUT is a high-impedance high-level output designed primarily to feed a power amplifier requiring 0.5 to 2 volts or the auxiliary or tuner input to an amplifier or tape recorder. This output will also drive the input of the Model M63 Audio Master.

Accessory 28-volt dc:

This rear panel jack marked ACCESSORY 28 V.D.C. provides 28 volts dc for accessories such as the Model

Model

A68M Microphone Preamplifier or M62V Level-

A68P Phono Preamplifier,

Loc. The jack is also used as the power input when

using the Model

sory) for battery operation of the

Designed to mate with Cannon

(Q.G.)

series or equivalent connector.

(female)].

A67B Battery Power Supply (acces-

M68P Mixer.

series, Switchcraft

[Shure

part

95A548

Power:

Connect the Microphone Mixer power line cord

to the proper ac power outlet. See Operating Voltage

OPERATION

under Specifications. The

cable with

Volume Controls:

three prong plug.

The MASTER gain control and the

M68P has a three-conductor

individual gain controls for each of the five channels

are identified on the front panel.

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 each control and recording that controls position when optimum results have been obtained. The labels are easily removed when their use is no longer required.

CONNECTING TWO UNITS TOGETHER

Two M68P Mixers may be combined to give a total

of eight microphone channels plus an auxiliary input.

A. Connect the AUX. OUTPUT of Unit

to the AUX.

INPUT of Unit 2.

Connect microphones to mixers and set each mi-

crophone input control to

position.

C. Take the output signal for recorder or P.A. amplifier

from the appropriate output jack on Unit

Set MASTER control on Unit 1 to position #4.

Set AUX. control on Unit 2 to position #lo.

F. The MASTER control on Unit 2 is now the MASTER

for all inputs.

Advance MASTER control (Unit 2) to about

po-

sition and adjust individual microphone controls for

proper level. If overall gain is too low or too high

the MASTER control (Unit 2) may be adjusted.

H. If an input to the auxiliary channel is needed, such

as for a tape recorder or tuner, use AUX. INPUT on

Unit

Use AUX. control on Unit 1 for level adjustment of the auxiliary source. The master gain control for the entire system is the MASTER control

on Unit

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

This Shure product is guaranteed in normal use to be free from electrical and mechanical defects for a period of one year from the date of purchase. Please

retain proof of purchase date. This guarantee includes all parts and labor.

SHIPPING INSTRUCTIONS

Carefully repack the unit and return it prepaid to

the factory. If outside the United States, return the unit

to your dealer or Authorized Shure Service Center for

repair. The unit will be returned to you prepaid.

OPTIONAL ACCESSORIES

Battery Power Supply Output Cable Kit Locking Panel Phono Preamp Rack Panel Kit

Stacking Kit

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

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

Interconnecting Cable .Model A68SC

Attache Case

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

Handle/Tilt Stand

Line Matching Transformer Microphone Preamplifier

.........

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

.........

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

.....

.......

.Model A67B

.Model A68C .Model A68L .hlodel A68P .Model A68R .Model A68S

.Model AC60

.Model A67H .Model A95 Series

.Model A68M

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