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222
HARTREY
AVE.,
EVANSTON,
IL.
60204
U.S.A.
MODEL
702
STAGE MONITOR
AREA CODE 3121866.2200 . CABLE: SHUREMICRO
TWX: 910-231-0048 TELEX: 72-4381
SPEAKER SYSTEM
I
OPERATION AND SERVICE MANUAL
DESCRIPTION
The Shure Model 702 is a high-quality, two-way loud-
speaker system designed for localized sound coverage in
on-stage monitor (foldback) applications. The 702 may be
used with virtually any power amplifier capable of deliv-
ering up to 50 watts to a 16-ohm load. The Speaker may
be placed in either of two slanted positions facing the
performer.
Excellent sound reproduction is achieved through the
use of two
&inch heavy-duty speakers and three piezo-
electric tweeters. The tweeters are arranged in a
cross-
firing configuration, providing uniform horizontal cover-
age. A volume control permits individual adjustment of
702 volume to suit each performer's needs. Nominal
impedance of the Speaker is 16 ohms with the volume
control at 10. Reduction of the volume control setting
reduces the overall volume and increases the Speaker
impedance. At the
0 setting, the Speaker is turned off.
If the 702 is the only Speaker connected to the amplifier,
the 702 volume control should be set to
10 and the
amplifier volume control adjusted as desired.
The 702 is constructed of 15.9 mm
(%
in.) wood and
covered in scuff-resistant black vinyl. The attractive black
sculptured fabric grille is rugged, cleanable, and replace-
able if damaged. A retractile handle and balanced design
contribute to ease of transporting. The corners of the 702
are equipped with steel protectors. Rubber feet on two
surfaces provide protection and offer the option of posi-
tioning at either a
30" or 60" angle to the stage.
A heavy-duty,
15m (50 ft), 18-gauge, rubber-jacketed
connecting cable with phone plugs is available as Shure
Model
RKC4, and a rugged vinyl slip-on protective cover
is available as Model
A702A.
SPECIFICATIONS
Power Rating
........
.Maximum recommended ampli-
fier output: 50 watts
continuous, 28 Vrms, 48V peak
to 16 ohms
Impedance
..........
.16 ohms nominal (volume
control at 10)
Frequency Response
.
,100 Hz
-
20 kHz (see Figure 1)
optimized for natural
wide-
range voice reproduction
TYPICAL FREQUENCY RESPONSE
FIGURE
1
Sound Pressure
........
Level (SPL) .EIA rating: 49.5 dB at 9.2m
(30 ft) from 1 milliwatt;
equivalent to 97 dB at 1.2m
(4 ft) with 1-watt input
Phasing (Polarity)
....
.Positive voltage on phone jack
tip produces positive sound
pressure
High-Frequency
...........
Section .Three piezoelectric tweeters
(cross-firing)
Low-Frequency
...........
Section .Two
8
in. speakers
Horizontal Distribution.
.SO0 (see Figure 2)
LEGEND
...........
8
kHz
TYPICAL POLAR PATTERNS
FIGURE
2
Copyright 1979. Shure Brothers Inc.
27A1352
(SL)
Printed in
U.S.A.
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Vertical Distribution
.
.
.llOO
Directivity Factor
R,
(Q)
. . . . . .
.
.
. . .
.
.8.1 at 1 kHz full octave measure-
ment
Environmental Resistance:
Operating
Temperature.
. . . .
.
-
7" to 43°C (20" to 110°F)
Storage
Temperature
. .
.
. . .
-
29" to 71 "C (-20" to 160°F)
Connectors
.
. . . .
.
. . . .
.Two parallel-wired phone jacks
Overall Dimensions
.
.
.
.395 mm H x 533 mm W x 264 mm
D
(15-9/16 in. x 21 in. x
10-3/8 in.)
Weight
.
. .
. .
. .
. .
.
. . .
.9.1 kg (20 Ib)
Construction
.
.
.
.
.
. .
.
.15.9 mm (5/8 in.) wood, black
vinyl covering, black fabric
grille, retractile handle, steel
corner protectors, rubber feet
Optional Accessories
.
.
RKC4 15m (50 ft) cable with
phone plugs
A702A Protective Cover
INSTALLATION
General
Position the 702 at the front of the stage in front of the
performer's microphone, with the speaker grille aimed
approximately at the back of the microphone. Note that
the 702 may be used at either a 30" or
60" angle to the
horizontal. The angle chosen should be that which pro-
vides the most direct line-of-sight to the performer and
also provides minimal visual interference with the audi-
ence. When only one 702 is used on a separate amplifier,
set the 702 volume control to 10 and adjust the amplifier
or mixer controls as desired. When several 702s are used
on the same amplifier, set at least one 702 volume con-
trol to 10 and adjust the others as necessary. Setting at
least one 702 to 10 will ensure maximum undistorted out-
put from the amplifier.
It is possible to optimize the 702 (maximum gain before
feedback, most natural sound, etc.), for various room con-
ditions with an equalizer such as the Shure Model
SR107
Audio Equalizer. Optimum system sound may be ob-
tained by "tuning" the equalizer with an equalization
analyzer system such as the Shure Model
M615AS.
Direct Amplifier Connection
The Speakers are designed to be used with power am-
plifiers having the following maximum output capabilities:
However, sine-wave signals delivering 50 watts to a
Speaker should be avoided in that they present a much
greater average power than does program material. Con-
sequently, when setting up or adjusting a sound system
with these Speakers, avoid the use of high-level,
continuous-type test signals.
Speaker Wiring
Determine the approximate distance from amplifier to
Speaker and use the proper wire gauge. Recommended
cables for the sizes listed are:
Distance
AWG
Suggested Cable
0-30m (0-100
ft)
18 Gauge Belden #8460, #8461, #9740, Sf8542
30-60m (100-200
ft)
I6 Gauge Belden #8470, #8471, #a472
To avoid the frequency losses, poor coverage, dead
zones, etc., resulting from improper speaker phasing in
multiple Speaker installations, all Speakers must be wired
in proper polarity. The cables listed above are
color-
coded to insure that identical connections are used. Note
that even common 18-gauge lamp cord ("zip cord") is
phase-coded with ribs along the outer jacket of one con-
ductor.
The Shure RKC4 is a
15m (50 ft), 18-gauge, rubber-
jacketed cable with phone plugs on both ends. The
unused phone jack may be used for additional,
parallel-
connected Speakers.
Checking Sound Coverage
When the Speakers, amplifier and other equipment
have been installed and connected, apply a fairly con-
stant level signal to the system (preferably pink noise or
program material) and walk around the stage area. Listen
for a smooth, even output from the Speakers, with mini-
mal differences in volume and tone, and no unclear or
"dead" spots. A dead spot-for audio purposes, an area
where no sound is heard, or where the sound level is
appreciably lower-may mean that the Speakers are not
covering that area, or that the speaker wires are con-
nected out-of-phase. Proper phasing may be readily
determined by checking the connections on each Speak-
er, but inadequate coverage generally requires Speaker
repositioning or adding Speakers.
SERVICE
INSTRUCTIONS
Speaker Servicing
1. Using an ohmmeter, measure the resistance be-
tween the tip and sleeve of a phone plug inserted
in a speaker jack. The dc resistance should be 12
to 16 ohms with the volume control at 10.
2. To gain access to the individual speakers, remove
the Phillips head screws on the grille.
3. Using an ohmmeter, measure the resistance of each
speaker voice coil. A clicking sound will be made
by a "good" speaker when an ohmmeter is con-
nected or disconnected. Note that the resistance
of each
&inch speaker cannot be measured with-
out disconnecting a lead from one of its terminals.
Each 8-inch speaker should measure between 7.5
and 9.5 ohms. The piezoelectric tweeters are capac-
itive and cannot be measured with an ohmmeter;
the capacitive value of each tweeter should be
between
.ll
and .I7 mF.