Shure 548 User manual

222 HARTREY AVE.. EVANSTON. IL. 60204 U.S.A.
8
MODELS 548,548SD, and 548SH
1 :K~T
UNIDYNEmIV
AREA CODE 3121866-2200 CABLE: SHUREMICRO
TWX: 910-231-0048 TELEX: 72-4381
SERIES
I
8
I
UAIA
AREA CODE 3121866.2200 CABLE: SHUREMICRO
SHEET
, and 548SH
UNIDYNE~ IV
SERIES I
UNIDIRECTIONAL DYNAMIC MICROPHONES
GENERAL
The UNIDYNEB IV Models 548,548SD, and 548SH are
dual-impedance unidirectional dynamic microphones
shipped connected for low-impedance operation. The
units provide wide range reproduction of music and
voice and can be effectively used outdoors and indoors.
The UNIDYNE IV is ideal for use by professional
entertainers in high quality theater-stage sound sys-
tems and recording, as well as in critical public-address
systems such as those used in political conventions
and legislatures, convention halls, hotels, public audi-
toriums, stadiums, cathedrals and churches.
Microphone Features:
.Unusually effective cardioid (unidirectional) pickup
pattern reduces feedback (annoying loudspeaker
"squeals") and prevents echoing (boominess) that
sometimes occurs in partially filled halls. Can also
be used closer to loudspeakers than usual without
creating feedback problems
Response especially effective for announcing, nar-
ration, vocal and instrumental music
Shock-mounted cartridge for quiet operation
Convenient selection of either high or low imped-
ance
The UNIDYNE IV has an exceptionally uniform uni-
directional pickup pattern that provides an effective .Built-in long-life On-Off switch (548SH, 548SD, and
solution to feedback problems in reverberant locations, 548SD-CN)
permits best utilization of space in small studios,
facilitates orchestral placement, and excludes un-
. Rugged professi~nalthree-pin audio connector on
wanted background noise. the microphone
The UNIDYNE IV features an extremely rugged all
. Strong, detachable cable especially selected for
effective shielding from hum pickup
metal case and a shock-mounted cartridge, insensitive
to handling noise or mechanical vibration.
. Supplied with an .050" wrench and a 4-40 socket
setscrew (see Figure 4) to securely lock the micro-
Models 548 and 548SD can be used as hand-held phone to the cable connector (548, 548SD, and
microphones or they can be stand-mounted with the 548SD-CN)
supplied A25B slip-in swivel adapter. Model 548 is
designed for applications -where a switch is not re-
. Versatile-for use in the hand or on a stand-
quired; Model 548SD is equipped with a magnetic reed indoors or outdoors
On-Off switch. Model 548SH has an On-Off switch on
the attached swivel assembly for stand-mounting.
.
Rugged and dependable under all operating con-
ditions
VARIATION Available in four versions: without switch (548),
with magnetic reed On-Off switch (548SD), with
Model 548SD-CN: Same as Model 548SD, except magnetic reed On-Off switch and three-pin pro-
supplied with professional three-pin male audio con- fessional audio-connector on equipment end of
nector on equipment end of cable. (See Specifications cable (548SD-CN), and with On-Off switch mounted
for details on cable.) on attached swivel assembly (548SH).
Copyright 1980, Shure Brothers Inc.
27A1559 (TC)
U.S. Patents 3,132,713, and 3,240,883
Printed in U.S.A.

SPECIFICATIONS
TYpe
Dynamic
Frequency Response
40 to 15,000 Hz (see Figure 1)
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TYPICAL FREQUENCY RESPONSE
FIGURE 1
Polar Pattern
Cardioid (unidirectional)-uniform with frequency,
symmetrical about axis (see Figure 2)
POLAR PATTERN
FIGURE 2
Impedance
Dual. Microphone rating impedance is 150 ohms
(240 ohms actual) for connection to microphone
inputs rated at 19 to 300 ohms and "High" for con-
nection to high-impedance microphone inputs. Wired
for low impedance as shipped.
Output Level (at 1,000 Hz) IMPEDANCE
Low
-
High
-
Open Circuit Voltage* .....-76.0 dB -54.0 dB
(.I58 mV) (2.0 mV)
Power Level** .
. . .... . . . . . -56.0 dB
*O dB = 1volt per microbar
**0dB = 1 milliwatt per 10 microbars
Switch
548SD and 548SD-CN: Built-in magnetic reed On-
Off switch with lockplate. To lock switch in On
position, remove screw on lockplate and turn lock-
plate 180". Reassemble and tighten screw.
548SH: Built-in slide-to-talk, positive detent On-Off
switch mounted on attached swivel assembly; sup-
plied with accessory lockplate.
Cartridge Shock Mount
Internal rubber vibration-isolator
Swivel
548SH: Positive action, permits tilting microphone
through 135", suitable for mounting on stand with
Ti"-27 thread
Swivel Adapter
548, 548SD, and 548SD-CN: Positive action, adjust-
able through 90" from vertical to horizontal, permits
easy removal for hand-held use, suitable for mount-
ing on stand with %"-27 thread
Case
Black and satin-chrome finished all-metal case and
grille with stainless steel screen
Cable
548, 548SD, 548SH-4.6m (15 ft) two-conductor
shielded (rubber-jacketed) with a professional three-
pin female audio connectort on the microphone end
548SD-CN-6.lm (20 ft) two-conductor shielded
(rubber-jacketed) with a professional three-pin fe-
male audio connectort on the microphone end and
a professional three-pin male audio connectort on
the equipment end
t Designed to mate with Cannon XL series, Switchcraft
A3 (Q.G.) series or equivalent connector.
Dimensions
See Figure 3
MODELS 548, 548SD AND 548SD-CN
OVERALL DIMENSIONS
I,
(1-116 IN I
5fV-27 THD
(L5f16 IN.) 41 1 mm
(I-Sf8 IN I
MODEL 548SH - OVERALL DIMENSIONS
FIGURE 3
Weight Net Combined
(less cable) Net Packaged
548SH 4609 7339 9449
(16 oz) (28% oz) (37 oz)
548
& 548SD 311g 7239 8429
(1102) (25% 02) (33 oz)
548SD-CN 311
g 7789 9759
(1102) (30% oz) (38% oz)
OPERATION
Models 548, 548SD, 548SD-CN, and 548SH are dual-
impedance microphones for connection to a 19 to 300
ohm rated input or to a high-impedance input. The mi-
crophones are shipped from the factory connected for
low-impedance operation.
The low-impedance connection (as shipped) is
recommended where long cable lengths are required
or under conditions of severe hum disturbance. The
permissible cable length is practically unlimited since
neither response nor level is appreciably affected by
long cables. Shure Model A95 Series Line Matching
Transformers are available for use when a low-imped-
ance microphone line is desirable but the associated
amplifier has a high-impedance input. These trans-
formers provide a proper impedance match between a
19 to 300 ohm microphone line and a high-impedance
input and are available with various input and output
connectors. IMPEDANCE SELECTION
Models 548, 548SD, and 548SD-CN are shipped con-
nected for low-impedance operation. To change to
high impedance (see Figures 4 and 5), proceed as
follows:
1. Remove plug element at receptacle end of mi-
crophone by turning slotted setscrew in (counter-
clockwise) and carefully withdrawing plug ele-
ment from case.
2. Disconnect 2-terminal impedance selection sock-
et from rear of plug element.

SLOTTED SET SCREW
r PLUG ELEMENT 7
EDANCE SELECTION
SOCKET
MODELS 548, 548SD AND 548SD-CN
IMPEDANCE SELECTION - RECEPTACLE END OF MICROPHONE
FIGURE 4
REED
SWITCH
CARTRIDGE TRANSFORM3 PROFESSIONAL THREE-PIN
CABLE
GROUND AUDIO CONNECTORS
TERMINAL-, rTERMINAL C0DED"A"
..LCE
BLACK I SOCKET (SHOWN IN LOW
:CASE GROUND IMPEDANCE POSITIONI
POSITIVE PRESSURE PRODUCES POSITIVE VOLTAGE ON PIN 2,
LOW IMPEDANCE; ON PIN I. HlGH IMPEDANCE.
MODELS 548SD AND 548SD-CN
INTERNAL CONNECTIONS
CARTRKXjE TRbNSFORMER PROFESSIONAL THREE-PIN CABLE
GROUND TERMIN,#&
TERMINAL-\ [CODED A
AUDIO CONNECTORS
UAl F FFUAl F
... - ...........
,BLACK ~TI!
YELLOW
ICASE GROUND
'-IMPEDANCE SELECTION
POSITIVE PRESSURE PRODUCES POSITIVE VOLTAGE 'OCKET IN
ON PIN 2, LOW IMPEDANCE; ON PIN I, HlGH IMPEDANCE. IMPEDANCE PoSITION)
MODEL 548 - INTERNAL CONNECTIONS
FIGURE 5
3. Reconnect 2-terminal impedance selection sock-
et in reverse position so that pin 3 of plug ele-
ment is inserted in socket terminal "H".
4. Reassemble plug element into microphone and
seat setscrew securely by turning out (clock-
wise).
Model 548SH is shipped connected for low-imped-
ance operation. To change to high impedance (see
Figure 6), proceed as follows:
1. Remove the two No. 2-56 screws holding the
switch to connector and switch housing.
2. Remove the nameplate and take the switch out
of the switch housing.
3. Proceed as described in steps 2 and 3 above.
4. Re-assemble switch and nameplate to switch
housing. Tighten screws securely.
CARTRIDGE TRANSFORMER SWITCH THREE-PIN PROFESSIONAL CABLE
WDlO CONNECTORS
MALE FEMPLE
bT
SHIELD I I
1 i;'o"g~4$
MODEL 548SH - INTERNAL CONNECTIONS
FIGURE 6
CONNECTIONS
When using the microphone in low impedance, the
BLACK and WHITE cable leads are the "hot" conduct-
ors for balanced line connections to a low-impedance
amplifier input; the shield is connected to the chassis
or amplifier ground.
When using the microphone in high impedance, the
WHITE cable lead is the "hot" conductor for connec-
tion to a high-impedance amplifier input; the shield
is connected to the chassis or amplifier ground. The
BLACK cable lead should be insulated at the equip-
ment end when not used.
PHASING
To test two microphones and/or their cables for
proper phasing, connect them to an amplifier and
talk or sing into them while holding them three or
four inches apart. The sound from the speakers should
be the same when talking into either microphone or
directly between them if they are in phase with each
other. If the sound drops drastically, or if a dead spot
is found when talking between the two microphones,
either the microphones or their cables (low impedance
only) are out of phase. All cables and microphones
should be tested in this manner to insure that they
are in phase with each other.
To change the phase of a low-impedance microphone
cable, either use a Shure A15PRS Phase Reverser
or interchange the wires connected to pins 2 and 3
of the connector. To change the phase of a micro-
phone, the microphone cartridge leads must be inter-
changed (see Figures 5 and 6). This should be per-
formed by your dealer, the Shure Factory Service
Department, or other qualified service personnel.
FURNISHED ACCESSORIES
......
Swivel Adapter (548, 548SD, 548SD-CN) .A25B
Connector Locking Kit (548, 548SD,
548SD-CN) ........................... 90CK1371
Lockplate (548SH) ..................... .90NR1371
OPTIONAL ACCESSORIES
Line Matching Transformer ............. .A95 Series
Windscreen
............................... A61WS
Quick Disconnect Adapter
(548, 548SD, 548SD-CN)
.............. .A45, A45B
(548SH) ................................... A47
Desk Stand
.................... .S37A, S39A, S40A
REPLACEMENT PARTS
Cartridge (all models) ......................... R48
Cable (548, 548SH, 548SD)
................... .C59
(548SD-CN) ......................... C50CN
Screen and Grille Assembly (all models) ..... .RK38G
Plug Element (all models) ................ .RK169P
On-Off Switch (548SD, 548SD-CN) .......... RKIO6S
(548SH) .................... RK32S
ARCHITECTS' SPECIFICATIONS
The microphone shall be a moving coil (dynamic)
type with a frequency response of 40 to 15,000 Hz. The
unit shall have a cardioid polar characteristic. The
cancellation at the sides shall be approximately 6 dB,
and the cancellation at the rear shall be 15 to 20 dB.
The microphone shall be dual impedance with a rated
impedance of 150 ohms for connection to microphone
inputs rated at 19 to 300 ohms and "High" for connec-
tion to high-impedance microphone inputs. (Imped-
ance change shall be solderless at the microphone
connector.)

The microphone output shall be:
Low Impedance
. . . . .. . . .. . . . ...-56.0 dB
0 dB = 1 milliwatt per 10microbars
High Impedance . . . . .... . . . . . . ..-54.0 dB
0 dB = 1volt per microbar
Models 548SD, 548SD-CN, and 548SH shall be
equipped with a built-in On-Off switch.
Models 548, 548SD, and 548SD-CN shall be provided
with a swivel adapter, adjustable through 90" from
vertical ta horizontal, and suitable for mounting on a
stand having a %"-27 thread.
Model 548SH shall be equipped with a swivel, ad-
justable through 135", and suitable for mounting on
a stand having a %"-27 thread.
Models 548, 548SD, and 548SH shall be provided
with a detachable 4.6m (15 ft) two-conductor shielded
cable with a professional three-pin audio connector*
(female) on the microphone end.
Model 548SD-CN shall be provided with a detachable
6.lm (20 ft) two-conductor shielded cable with profes-
sional three-pin audio connectors* (male and female)
on the equipment and microphone ends.
The overall dimensions of Models 548, 548SD, and
548SD-CN shall be 157 mm (6-3/16
in.) in length and
40 mm (1-9116 in.) in diameter.
The overall dimensions of Model 548SH shall be 120
mm (4-23/32 in.) in height, 148 mm (5-27132 in.) in
depth, and 39.7 mm (1-9/16 in.) in width.
The microphone shall be the Shure Model 548,
548SD, 548SD-CN, 548SH, or equivalent.
*Designed to mate with Cannon XL series, Switchcraft A3
(Q.G.) series or equivalent connector.
GUARANTEE
This Shure product is guaranteed in normal use to
be free from electrical and mechanical defects for a
period of one year from date of purchase. Please
retain proof of purchase date. This guarantee includes
all parts and labor. This guarantee is in lieu of any and
all other guarantees or warranties, express or implied,
and there shall be no recovery for any consequential
or incidental damages.
SHIPPING INSTRUCTIONS
Carefully repack the unit and return it prepaid to:
Shure Brothers Incorporated
Attention: Service Department
1501 West Shure Drive
Arlington Heights, Illinois 60004
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.