Shure 245, 245S, 245G, 245GS User Guide

222

HARTREY AYE.. EVANSTON.

AREACODE312/328.9000 CABLE: SHUREMICRO

l

L.

60204

Unidirectional Ceramic Microphones

Using

A25

Swivel

Mounted on

GENERAL:

oid ceramic microphones employing the Shure "Uniphase"
principle. The cardioid characteristics allow satisfactory op­eration under adverse conditions of background noise and
reverberation, where operation of a conventional micro­phone would be rather limited.

Model "245" contains a diaphragm actuated element,
combined with acoustical networks, which cause cancellation
of sound pressures for sounds incident from the rear. The
transducer element is a lead zirconate titanate ceramic,

usable without damage from 40°C

(+

170°F.) and is not damaged

chrome case is designed for improved acoustical

mance and appearance.

The symmetrical design of the Model "245" series
crophones, coupled with reduced size and weight, makes
them more versatile in use

neck,

or handheld.
a 15 foot (4.6m) single-conductor shielded cab
(equivalent to amphenol MCIF] for attaching the cable to
the microphone. In Models

I

m) single-conductor shielded cables are attached to the

2.

microphone. Models 245 and
Model A25 swivel adapter. The swivel adapter has

-27 thread and may be mounted on the S38B Desk Stand
or any conventional desk or floor stand. The swivel adapter
is not required when the microphone is handheld. The

Models

used with flexible goosenecks having a

customized installation where a concealed cable is desired.

Models 245s and 2456s have a built-in switch to con-

trol the microphone circuit. Models 245 and

no switch.

5388 Desk Stand

Model "245" series microphones are cardi-

(40°F.)

by

humidity. The rich satin

-

desk, stand, mounted goose-

Models

2456 and 2456s are especially designed to be

245 and 245s are

2456 and 24565 the 7 foot

2455 are provided with the

5/8"-27 thread or

to

rovided

I'

e with a plug

2456 have

Mounted on As A

Flexible Gooseneck Handheld Unit

+76"C

perfor-

mi-

a

5/8"

U.S.A.

MODELS 245, 245S, 245G.

SHEET

I

DATA

-55

2

-60

W

5

'65

-70

w

2

-75

2

-80

cr

The frequency response of the Model 245 series is from
50 to 7000
symmetrical about the axis wit the response down
the sides, 15
duced rear response feature permits more volume without
feedback which simplifies microphone and speaker placement

and

phones.

270

greatly

Hz.

(See

db

or more at the rear. (See Figure

and 245GS 'Uniplex"

FREQUENCY

FREQUENCY RESPONSE

Figure

IN

FIGURE

A.

The

HERTZ

A

microphone

I

'ystems using

. . . . . . . .

. .

. .

.

conventional

response

6

db

B.)

This re-

micro-

90°

I

is

at

APPLICATIONS:

for quality public address communications, all types of re-

cording, and similar applications.

The wide range angle unidirectional characteristic of

the "Uniplex" provides an inherent reduction of the feed-

back problem in reverberant locations, facilitates orchestral
placement and provides an effective reduction of unwanted
noises.

Copyright

27A191

1961,

(LD)

Shure Brothers

The Model 245 "Uniplex" is excellent

Inc.

(OVER)

0°

Typical Directional Pattern

FIGURE

B

Printed in

U.S.A.

CONNECTIONS:

lead of the microphone cable to the coupling capacitor
feeding the grid of the first
load resistance of 5 megohms. (See Figure
sistances as low as
higher values are recommended because of the better low
frequency response which will result. The shield or ground
should be connected to the chassis. The shield, chassis, or
amplifier ground should be securely connected to a water
pipe or similar ground to prevent shock hazard during op­eration of the amplifying system.

Added lengths of connecting cable will be accompanied
by a decrease in output level. There is no frequency dis­crimination introduced by the cable, regardless of length.
Most modern high-gain amplifiers have a sufficient margin
of gain to make up for output level decreases due to addi­tional cable lengths.
essary gain, a
main amplifier, is suggested. Pre-amplifiers with low imped­ance output are recommended
has a low impedance transformer or mixer input.
should be of high quality and low capacity.

pre-amplifier at the microphone, or near the

OPERATION:

amic micro hones. Ceramic microphones may be seriously

i

P

damaged
supply outlets carrying

careful1

~ien used near a transmitter, use minimum length of ca­ble consistent with placement requirements. Careful ground­ing of cable shield is advisable.

The normal temperature-humidity precautions associated
with crystal elements do not apply with the "Uniplex" cer­amic element as
+7b°C
providing greater environmen+al range o operation, with no
special precautions, beyond ordinary care, for the efficient
and dependable operation of the "Uniplex" Microphone.

Models

amic microphones have a built-in switch to control the mi-

crophone circuit. The switch has a press-to-talk locking or

non-locking feature, having long-life phosphor-bronze blades
with fine silver contacts. For momentary contact, depress
switch button and release. For locking, depress switch but­ton and slide button upwards. When not depressed the

switch achieves normal nonoperative conditions by shorting
the hot lead of the ceramic element and connecting cable

conductor to shield or ground.

accidental1 connected to loudspeaker or power

.

(+

170°F.) and is not damaged b humi ity, thereby

2455 and 2456s "Uniplex" Unidirectional cer-

Connect the inner conductor or hot

tube in the amplifier across a

I

megohm may be used

FIGURE

CONNECTIONS

If

the amplifier does not have the nec-

No polarizing voltage is required for cer-

Xigh voltage. Check your connections

it

is usable from

C

if

the main amplifier system

40°C

C.)

Input re-

if

necessary, but

AMPLIFIER WITH HIGH
IMPEDANCE

INPUT

-4°F.) to

Cable

d

r

I

I

ACOUSTIC CONSIDERATIONS:

"cardioid type response"
acteristic of the microphone approximates a cardioid of
revolution. (See Figure
angle at the front of the microphone. The rear response
down over a broad range of frequencies and reduces pickup
of random energy by 67%.

The Shure "Uniplex" employs the same type of acous­tic phase shifting network used in the highest cost Shure
microphones. The unidirectional cardioid characteristics of
the "Uniplex" allows satisfactory operation under adverse
conditions of background noise and reverberation where op­eration of a conventional microphone would be rather lim­ited. By directing the rear side of the microphone towards
the audience or other source of interfering sound, pickup
can be concentrated on the desired source. The microphone
can be placed close to reflecting surfaces without
able effects
reflecting surface. This
dios or rooms.

It

ment and orientation in order to secure the greatest benefits
from the unidirectional characteristic.

if

the rear side of the microphone is toward the

is desirable to experiment with microphone place-

simply means that the polar char-

6.) There is a wide, useful pickup

is

particularly valuable in small stu-

-

27

FITS AMPHENOL
MClF PLUG.

The expression

is

obiection-

.NS-2 THREAD

7

(49.6

mm)

FIGURE

OVERALL DIMENSIONS

SPECIFICATIONS

Voltage Sensitivity:

end of
equivalent to 59

EIA Microphone rating
EIA Standard SE-105, August, 1949

7

feet (2.lm) cable across I to 5 megohms. This

db

below I volt per microbar.

GM

Internal Output Impedance:

picofarad condenser.

Recommended Load Impedance:
Weight:

Dimensions:

Guarantee:

use to be free from
for a
retain proof of purchase date. This guarantee includes
all parts and labor.

Net

%

lb.

(170 g), Packaged
See Fig.
This Shure product is guaranteed in normal

eledrical and mechanical defects

~eriod of one year from the date of purchase. Please

Shipping Instructions:

and return
States, return the unit to your dealer or Authorized Shure
Service Center for repair. The unit will be returned to you
prepaid.

it

prepaid to the factory.

D

I.

10 millivolts per microbar at

(sensitivity) - 159

Equivalent to a 935

3/4

db

I

to 5 megohms.

Ib.

340 g).

D.

Carefully repack the unit

If

outside the United

is