Shure SR108 User Guide

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222 HARTREY AVE., EVANSTON. IL. 60204 U.S.A.

AREA CODE312/866-2200 CABLE: SHUREMICRO

TWX: 910-231-0048 TELEX: 72.4381

OPERATION AND SERVICE INSTRUCTIONS

FIGURE

SR108 SPEAKER SYSTEM

DESCRIPTION

The Shure Model SR108 Extended Range Speaker System is a rugged, heavy-duty, two-way speaker system designed primarily for high sound-pressure-level reproduction of wide-frequency-range program material in sound reinforcement applications. The can be used with Shure Model SR105 or similar high-

power amplifiers, in either a single-amplifier mode (conventional full-range operation with passive crossover) or, with a Shure Model over, in a biamplification mode of operation. The is also ideal for monitoring applications requiring wide frequency response and high signal level capabilities. When properly installed and connected, the

provide outstanding performance in critical, high-level applications due to its extremely wide frequency response, low distortion and smooth dispersion characteristics. The

ohms and is designed to operate with up to 57 volts

rms input (200 watts continuous program material). In

SR108 has a nominal impedance of 16

SR106 Electronic Cross-

SR108

SR108 will

DATA

SHEET

the biamplification mode, the low-frequency section accepts up to 200 watts and the high-frequency section up to 100 watts of continuous program material. The SR108 can be used either direct-coupled or with a constant-voltage 70-volt line using a Shure Transformer.

The superior sound quality of the through the use of six eight-inch low-frequency speakers, mounted in a linear array in a front-ported, loaded, bass reflex enclosure (fourth-order Butterworth response) plus four high-frequency drivers coupled to a single radial horn. The front-porting bass reflex design of the enclosure provides extreme quency enhancement, and horn-loading optimizes the lower mid-range frequencies. A built-in series-type

passive crossover network is used with single-amplifier inputs, and includes a four-position high-frequency attenuator switch (LOUDSPEAKER OPERATION).

The LOUDSPEAKER OPERATION Switch is also used to select between the single-amplifier, passive crossover input and separate high- and low-frequency inputs for operation in the biamplification mode. The Shure Model the proper low-frequency and high-frequency signal splitting ahead of the power amplifiers for biamplified operation.

The high-frequency section of the tains automatic protection circuitry to avoid driver damage at extremely high input levels. Additional high-frequency driver protection is included in the amplification mode to protect against damage from

low-frequency signals.

The

SR108 is a portable unit, and is primarily designed for easy installation either indoors or in a protected outdoor environment, such as under an open pavilion. The system is supplied with a (50-foot), 18-gauge, rubber-jacketed connecting cable with phone plugs. (A second connecting cable-Shure

RKC4, not supplied-is required for operation in

No. the biamplification mode.) The upper right rear section of the

durable wood, coated with black, scuff-resistant, textured vinyl. All adhesives used in the moisture-resistant, and internal bracing is provided to minimize vibration and maximize structural integrity. The metal grille assembly is finished in durable gold enamel. The radial horn is ruggedly constructed of high-density, structural urethane foam, with fastening hardware selected to provide strength and minimize corrosion and visible wear. The with an integral rear-panel handle and two heavy-duty,

hard-rubber wheels for mobility.

SR108 contains a cable storage compartment.

The

SR108 is constructed of 15.9 mm

SR106 Electronic Crossover provides

MODEL SR108 EXTENDED

RANGE SPEAKER SYSTEM

A102A

SR108 is achieved

horn-

low-fre-

SR108 also con-

bi-

15.2111

(5/8

in.) heavy

SR108 are

SR108 is equipped

27A1355

1977,

(QC)

Shure Brothers

Inc.

Printed

U.S.A.

SPECIFICATIONS

Power Rating

(Program Material) Single Amplifier

Low-Frequency lnput

(Biamplification High-Frequency lnput

(Biamplification

Power Load for

Constant-Voltage Operation

Impedance

Frequency Response

Crossover Frequency Sound Pressure

Level (SPL)

Total Harmonic

Distortion

Phasing (Polarity)

Single Amplifier

Biamplification

High-Frequency

Section

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

Horizontal Distribution

Vertical Distribution Operating Temperature.. Storage Temperature Connectors

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

Overall Dimensions

(see Figure E)

Weight

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

Construction

lnput..200 watts max. Mode)..200 watts max. Mode)..100 watts max.

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

....

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

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

Input-.Positive voltage applied to phone

Mode..Low Frequency: Positive voltage

......

....

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

-64.5 kg (142 Ib) incl. cable

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

39 watts

(25-volt input, 16 ohms)

50 watts

(70.7-volt input, through

optional

A102A Transformer)

36 ohms nominal for both con-

ventional full-range and biamplified operation (see Figure B)

40 Hz - 15 kHz

(see Figure C)

2600 Hz nominal

ElA rating: 54 dB at 9.2m (30

feet) from 1 milliwatt; equivalent to 102 dB at

1.2m (4 feet)

with I-watt input

Less than 2% at 1 kHz and 10

kHz; less than 3% at 100 Hz

1.8m

[measured at

feet) and

106 dB SPL]

plug tip produces positive

sound pressure.

applied to phone plug tip produces positive sound pressure.

High Frequency: Positive voltage

applied to phone plug tip pro-

duces negative sound pressure.

120" radial horn

..140° (see Figure D)

90" (1 kHz -10 dB)

7" to 43°C (20" to 110°F)

29" to 71 "C

20" to 160°F)

Two parallel-wired phone jacks

for each input: conventional full-range, low frequency and

high frequency

1730 mm height x 495 mm width

517 mm depth (68% in.

19% in. x 20% in.)

15.9 mm

in.) wood, black vinyl finish, gold-painted metal grille, anodized aluminum rear panel rails, structural urethane foam horn

Supplied Accessories

Optional Accessories

20 40

100

200 400 600 IK 2K 4K 6K IOK 2OK

IMPEDANCE CURVE

105

/I I

LWDSPEAKER OPERATION

I00

TYPICAL FREQUENCY RESPONSE

I-

TYPICAL HORIZONTAL POLAR PATTERN

....

One 15.2m (50-foot) heavy-duty

cable with phone plugs

....

A102A 70-Volt Transformer A50XC 15.2m (50-foot) Extension

Cable with male and female phone plugs

RKC4

15.2m (50-foot) Heavy-Duty Cable with male phone plugs (for biamplified operation)

FREQUENCY

FIGURE

200

400

FREQUENCY

(HZ)

TO Z"

STERAMAN

SWW

1111l1

WO IK 2K 4K

(HZ)

I lllllll I\U

FIGURE C.

LEGEND

-----

...........

I(::

KHz

FIGURE D.

(RKC4)

IOK

20K

r""::

CONENTICUM

r.~?

(4-

3/8

IN.)

FULL-RANGE

lpUr

PASSIVE

mgmER

FULL RANGE

HIGH-FI1EWENCY

ATTENUATION

FIGURE

OVERALL DIMENSIONS

CIRCUIT DESCRIPTION

In conventional, full-range, single-amplifier opera-

tion, input signals from the power amplifier are con-

nected to the

parallel-wired jacks to a series-type, passive LC crossover network composed of two capacitors and two inductors (see Figure F). The crossover provides

a 6

dB1octave rolloff for the low-frequency speakers and an 18 drivers. The inductance of the low-frequency speaker voice coils provides an additional 6

resulting in a total of 12 dB1octave low-frequency rolloff.

Low-frequency signals are routed from the crossover directly to the six low-frequency speakers through the rear-panel LOUDSPEAKER OPERATION Switch.

The low-frequency speakers are wired in two parallel

sets of three series-connected speakers, providing a total nominal impedance of 16 ohms. High-frequency signals are routed from the crossover through the LOUDSPEAKER OPERATION Switch attenuator network which provides high-frequency level adjustments of -4, -2, 0, and of the switch. From the attenuator network, high-

frequency signals enter a protection circuit designed to prevent damage to the high-frequency drivers by

extremely high signal levels. Signal levels greater than 28 volts rms (approximately 50 watts) for longer than 15 milliseconds are sensed through a diode bridge, causing a relay to engage high-wattage resistors which decrease the high-level signals to the highfrequency drivers by approximately

cuitry automatically resets itself when the quency signals drops below a safe threshold level.

The output of the protection circuitry feeds the four

SR108 through the uppermost set of

dB/octave rolloff for the high-frequency

dB1octave rolloff,

+2 dB in the first four positions

dB. The cir-

high-fre-

BUW

LOI-FREOUENCI

WUT

high-frequency drivers which are wired in seriesparallel and provide a total nominal impedance of

ohms.

Operation in the biamplification mode is accomplished by feeding separate high- and low-frequency signals from an external 2600 Hz electronic crossover, such as the Shure Model

through separate high- and low-frequency power amplifiers, such as the Shure Model

plifier, to the

of the

LOUDSPEAKER OPERATION Switch in the

position, the internal passive crossover of the SR108

is bypassed, and the low-frequency signals are routed

directly to the low-frequency speakers. High-frequency signals also bypass the attenuator network, going di-

rectly from the LOUDSPEAKER OPERATION Switch

through the high-frequency protection circuit and a 12 filter serves to protect the drivers from low-frequency transient signals produced by connecting input cables to the power amplifier, turn-on thumps, or operating errors.

SR108 (see Figure G). With the rear-panel

dB1octave filter to the high-frequency drivers. The

AUDIO CWSOLE ELECTRONIC

8mCn

SR108 BLOCK DIAGRAM

HlGH and LOW FREQUENCY input jacks

CROSSOVER

(2600HZ1

BIAMPLlFlED OPERATION

FULL-RANGE

SHOWN

FIGURE F.

FIGURE G.

FULL

RAW€

WKN

SR106 Electronic Crossover,

SR105 Power Am-

HIGH POWER HIGH-FREQUENCY

AMPLIFIER

r-------1

BlAMP

SRlOB

SPEAKER SYSTEM

DRIVERS

INSTALLATION

General

In planning a sound system using the SR108 Ex-

tended Range Speaker System, care must be taken to observe the horizontal (140") and vertical (90") sound distribution. Maximum coverage for sound reinforcement installations is generally obtained with SR108's on each side of the sound source and as far forward as possible. Assuming a single to either side of the sound source, the SR108's should be positioned so that an imaginary line from the center of each audience area. For "clustered"

SR108 runs to the back row of the

SR108 installations

SR108

covering a wide area, each SR108 should be positioned so that its angle of coverage slightly overlaps that of the

SR108 next to it as their sound output

enters the audience area.

The problem of audience penetration may be likened to illuminating a dark area with a floodlight: the object is to provide maximum area coverage (audience) with the available floodlights

(SR108's). At the same time, care must be taken to avoid illuminating reflective surfaces. A blinding reflection (echo or

"slap-

back") may be more of a problem than inadequate

coverage of the desired area.

Of the remaining common sound installation problems, acoustic feedback can usually be dealt with by judicious placement of

SR108's and microphones, and/or the use of feedback filters on the audio console. Extreme background noise or acoustic absorp-

tion generally requires a greater volume level to maintain an acceptable sound level. However, it must be remembered that excessive sound levels may be intolerable to that part of the audience nearest the

SR108's. In this case, or in those cases where the

architectural design leaves audience areas that are

not reached by the

SR108's, the use of secondary or

auxiliary speaker systems should be considered.

Conventional

The

SR108 is designed to accept program material

Full-Range Direct-Coupled Operation

where the average power level reaches 200 watts on a continuous basis. However, sine-wave or pink or white noise signals of levels approaching 200 watts should be avoided in that their duty cycle is much greater

than that of program material. Consequently, when

setting up or adjusting a sound system with

SR108's, avoid the use of high-level, continuous-type test signals. It should be pointed out that the various speaker input jack pairs are for paralleling additional speakers

not

and

amplifiers.

CAUTION Amplifier damage may result if two amplifiers are plugged into parallel jacks.

To insure safe operation of

SR108's with program

material inputs, do not connect any input jack to an amplifier or amplifiers with output capabilities greater than shown in Figure

70-Volt Operation

The

SR108 Speaker System may be used on a constant-voltage, 70.7-volt line by using a 70-volt transformer such as the Shure Model

A102A. This trans-

former provides power taps of 50, 25, 12, and 6

watts and speaker impedance taps of 8 or 16 ohms

(see Figure J).

In the

biamplification mode, connect A102A trans-

formers using one transformer for the high-frequency

input and one for the low-frequency input. Connect the low-frequency amplifier 70-volt line to the power tap of one

A102A transformer, choosing the tap that produces the desired power level. Connect the high-frequency amplifier 70-volt line to the power tap of the other transfomer offering the most suitable balance of high- to low-frequency sound. First try the

high-

frequency power tap that is one-half the power of

the low-frequency tap.

Listen to program material

NOT

WITH THAN

MANUAL

INPUT

HIGH FREO

AMP

FULL RANGE

'OW

BIAMP

LOW FREO SECTION BIAMP OPERATION

IXlERNAL LOW

CONNECT

OUTPUT

THE

VALUES

FOR

ADDITIONAL

CONTINUOUS

POWER

TO 16 OHMS

100

WATTS

FREa

;,"As

LOUDSPEAKER

CONVENTIONAL FULL-RANGE OPERATION

OHMS

P1SS

REOUlRED (1600HZ bOB/OCTAVE) llOUlRlD i1600HZ I1OB/OCTAVBl

THIS SPEAKER CAN PRODUCE SOUND PRESSURE LEVELS WHICH MAY CAUSE PERMANENT HEARING DAMAGE AFTER PROLONGED EXPOSURE.

CROSSOVER NETWORK

CAUTION

LOUDSPEAKER

POWER

INDICATED

AMPLIFIER OUTPUT SHOULD NOT EXCEED

CONTINUOUS

POWER

TO 8 OHMS

200

WATTS

400

WATTS

PARALLEL

I_I

16 OHMS

WARNING

FIGURE

VOLTAGE

BELOW.

INFORMATION.

CONTINUOUS

POWER

TO 4 OHMS

400

WATTS

800

WATTS

CONNECTION

HIGH FREO SECTION

EXTERNAL

POWER AMPLIFIER

RATING

SEE

INSTRUCTION

CONTINUOUS

OUTPUT

VOLTAGE

VOLTS

RMS

VOLTS

RMS

PARALLEL

BIAMP OPERATION

OHMS

HIGH

PASS CROS1016. N11WORK

GREATER

PEAK

VOLTS

SPEAKER INPUTS

through the sound system and adjust the high-frequency power tap if a different

high-frequency/low-

frequency balance is desired. Phasing (Polarity)

The

SR108 is phase-wired for conventional, fullrange operation as follows: A positive voltage applied to the CONVENTIONAL FULL-RANGE OPERATION lnput Jack tips will produce a positive sound pres-

sure below 2600 Hz and a negative sound pressure

above 2600 Hz. In biamplified operation, a positive

voltage applied to the LOW

FREQ/BIAMP OPERA-

TION lnput Jack tips produces a positive sound pres-

sure, and a positive voltage applied to the

FREQ/BIAMP

OPERATION lnput Jack tips produces

HlGH

a negative sound pressure. This conforms to the

requirements of the

SR108 internal passive crossover network, which provides the proper phase relationships at the crossover frequency.

When using the

SR108 in biarnplified operation with an external active electronic crossover network and separate power amplifiers, the following considerations should be given to phasing: When using a Shure Model cal power amplifiers (Shure

power an

SR106 Electronic Crossover and identi-

SR105 or equivalent) to

SR108, the phasing is correct. Dissimilar

high- and low-frequency power amplifiers may be

A102A

POWER

70.7

"HOT"

GROUND

LlHE

-I

02=w

12W

COM

50-6 WATTS

FIGURE

SYSTEM

70-VOLT OPERATION

used as long as all low-frequency sections are in

phase with one another and all high-frequency sections are in phase with one another. A potential problem exists only when there is a phase reversal between the high- or low-frequency sections of the speaker systems in use. To check for a possible out-of-phase condition, the following listening test should be per-

formed on both high- and low-frequency sections of the

SR108's at a time (using one SR108 as a phase ref-

erence) with the same program material (vocal material, or pink noise). Connect the

plifiers,

Turn on the sound system and adjust for a moderate

level. Disconnect the high-frequency driver input ca-

bles. Stand approximately mid-way between the two

SR108's and listen to the program material while

reversing the "hot" and common leads to one of the low-frequency speaker sections. (This may be accomplished by wire-reversing or by a simple

wired, double-pole, double-throw switch.) Use the connection that gives a localized sound, centered between the tion.

phasing.

disconnect the low-frequency sections. Perform the same test as above. Correct phasing will provide a

localized sound, centered between the correct phasing is indicated by the sound appearing to come predominantly from one

from one around the audience area. NOTE: In a mixed system

(both conventional full range and biamplified) the

high-frequency driver sections are normally out of

high-frequency signals must be reversed to assure

that the high-frequency drivers of all speaker systems

are in phase. This may be accomplished with a Shure A15PR Phase Reverser at the high-frequency amplifier

input or the

SR108's. The test should be made feeding two

SR106, power am-

SR108's, and program input equipment.

CAUTION

Do not interchange high- and low-frequency speaker cables. Damage to high-frequency drivers from high-level, low-frequency signals may result.

cross-

SR108's; this is the correct phase connec-

diffuse, directionless sound indicates improper

AWLlCEI-TO-SPEIKER DISTANCE VEETl

AMPLIFER-TO-SPEAKER DISTANCE IYLTLRSI

RECOMMENDED WIRE GAUGE:

FIGURE

DIRECT-COUPLED AMPLIFIER OUTPUT

Reconnect the high-frequency driver sections and

SR108 to another as the listener moves

phase with one another. Therefore, the biamplified

SR106 high-frequency output.

SR108's; in-

SR108 and to shift

Wiring

The cables used to connect the SR108 should be at least 18-gauge and rubber-jacketed. Determine the approximate distance from the amplifier to the and refer to Figures K or L to find the proper wire gauge for direct or 70-volt amplifier output (with A102A transformer) operation. Recommended cables

for the sizes listed in Figure K and L are:

Gauge

AWG 18

AWG 16

AWG 14 AWG 12 AWG 10

*Cross-section of American Wire Gauge (AWG)

To avoid frequency cancellations, poor coverage,

dead zones, etc., resulting from improper speaker

phasing, the The cables listed above are color-coded to ensure that identical connections are used for each

SR108 cord ("zip cord") is phase-coded with a ribbed outer jacket, color-coded threads, or tinned and untinned

conductors.

supplied with the

operation, connect the right-angle plug to a phone

jack marked CONVENTIONAL FULL-RANGE OPERA-

TION and twist the cable downward behind the locking

bar to prevent accidental disconnection. The other

phone jack may be used for additional, parallel-con-

nected SR108's. When not in use, the cable may be

stored in the compartment at the top right of the rear

a second cable (Shure

input phone jacks. The same wire gauge constraints

to operation in the biamplification mode. Two separate

cables (four wires) should be used for amplifier-to-

SR108 interconnection in biamplified operation. Note

that the

ever, the wire gauge of the common wire should be

one size larger than the gauge indicated in Figure

given to positioning of the cables. While most local

Placement

marily designed for free-standing operation. In posi-

tioning for optimum sound coverage, care must be

taken to locate the

away from areas where the movement of performers,

hookup. Note that even common 18-gauge lamp

When using the 15.2m (50-foot), heavy-duty cable

panel.

When wiring the SR108 for biamplification operation, provide connections to both the listed above for conventional full range operation apply

SR108 high- and low-frequency inputs are

isolated and a three-wire cable could be used; how-

When wiring the electrical codes do not require locating speaker

cables in conduits or raceways, make sure that cable placement minimizes traffic interference and physical abuse to the cable or

The SR108 Extended Range Speaker System is pri-

Belden

8460, 8461,

9720, 8452

y28471,

SR108's must be wired in proper polarity.

8473

8477 3.3

SR108 in conventional full-range

RKC4) must be obtained to

SR108's consideration should

SR108.

SR108's on stable surfaces and

Area (mm2)*

0.8

1.3

2.1

5.3

HIGH and LOW FREQ

SR108

amplifier-

FIGURE

RECOMMENDED WIRE GAUGE: 70-VOLT AMPLIFIER OUTPUT (USING A102A TRANSFORMER)

audience, curtains or stage sets may cause inadvertent movement (tipping or sliding). If potentially hazardous locations cannot be avoided, the secured with rope, cable or strapping to maintain

their physical positions and prevent accidents.

If it becomes necessary to elevate the

proper sound coverage, adequate support for eleva-

tions up to about three feet can usually be obtained

using a sturdy table or bench. It should be established in advance that the surface is capable of supporting the 64.5 kg (142 Ib) weight of the

For elevations greater than three feet, it is important to note that the cable or bracket mounting. A heavy-duty shelf-type mounting capable of supporting the weight of the

SR108 should be devised for wall-mounted locations.

Shelf and supporting materials, hardware and wall

structure must be carefully considered when planning this type of mounting. The building contractor, architect or engineer should be consulted to provide building construction information and verify the safety of the proposed mounting plan. Whenever possible, a backplate should be used on the opposite side of the mounting wall to secure the mounting hardware, and some means of preventing possible sliding off the shelf must be devised.

SR108 is

not

SR108's should be

SR108 for

SR108.

designed for simple chain,

WARNING

Under no circumstances should an SR108 be hung by eyebolts and chains or cables attached to the sides, rear, handle or top. The

SR108 enclosure is not designed to withstand the stresses incurred in this type of mounting.

or cables. As in wall-mounting, careful consideration must be given to the materials, hardware and chain or cable mounting surface. The cable or chains must be located at each corner of the platform, and should be capable of supporting four times the total weight

system, a Shure

connected between each amplifier and

A102A Transformer is used, it should be located as

close to the

of the

mm the

of the

If the

SR108.

SR108

(3Y4

plus

the platform.

SR108 is to be used on a constant-voltage

A102A 70-Volt Transformer must be

SR108. If the

SR108 as possible. If mounted to the rear

SR108, the transformer adds approximately 82

in.) in depth and 2.95 kg (6 Ib) in weight to

Checking Sound Coverage

When the SR108's, amplifiers and other equipment

have been installed and connected, apply a fairly con-

stant level signal to the system (preferably a uniform

level, full frequency range program material) and walk

around the audience area. Listen for a smooth, even output from the volume and tone, and no distortion or "dead spots." A dead spot-for audio purposes, an audience area where no sound is heard, or where the sound level

is appreciably lower than the rest of the audience area-may mean that the

area; or that the SR108 speaker wires are con-

that

nected out-of-phase. Proper phasing (polarity) may be

readily determined by checking the connections to the phone jacks on each are the same; inadequate coverage generally requires

repositioning the

Should a dead area be encountered, it should be carefully examined to determine if the problem can be corrected without resorting to auxiliary speakers.

SR108's with minimal differences in

SR108's are not covering

SR108 to make sure they

SR108's.

BlAMPLlFlCATlON

If suspended mounting, using chains or cables attached to beams or girders, is an absolute necessity, a platform must be devised which will be capable of

both supporting the

SR108 and retaining the chains

The data in this section relates only to the use of

SR108 in the biamplified mode. Some portions of

the

data in preceding sections are repeated here to pro-

vide a comprehensive section on biamplification.

Circuit Description

Biamplified operation is accomplished by feeding

separate high- and low-frequency signals from an

external 2600 Hz active crossover network, such as

the Shure Model

SR106 Electronic Crossover, through separate high- and low-f requency power amplifiers, such as the Shure Model the HlGH and LOW FREQ lnput Jacks of the

SR105 Power Amplifier, to

SR108 (see Figure G). With the rear-panel LOUDSPEAKER OPERATION Switch in the

passive crossover of the

BIAMP position, the internal

SR108 is bypassed, with the

low-frequency signals routed directly to the low-frequency speakers (see Figure F). High-frequency signals also bypass the internal passive crossover and bypass the attenuator network, going directly from the LOUDSPEAKER OPERATION Switch through the high-frequency protection circuit to the high-frequency drivers. In the biamplified mode, the high-frequency protection circuit includes an overvoltage attenuator network, and a capacitor-inductor, low-frequency

rolloff network which protects the high-frequency drivers from low-frequency transient signals produced by connecting input cables to the power amplifier, turn-on thumps, or operating errors.

Direct-Coupled Operation

To avoid damage to speakers or drivers when set-

ting up or adjusting a sound system using the

SR108, avoid the use of high-level, continuous-type test signals. Program-type material up to 200 watts may be

used without special precautions.

For optimum safe operation in the biamplified mode,

do not connect the HlGH or LOW FREQ lnput Jacks

of the

SR108 to amplifiers with output capabilities

exceeding those shown in Figure H.

CAUTION

Do not interchange the high- and low-frequency speaker cables. Damage to the highfrequency drivers due to high-level, lowfrequency signals may result.

70-Volt Operation

For biamplified operation from a constant-voltage, 70-volt line, connect Shure between the power amplifiers and

A102A 70-Volt Transformers

SR108 as follows:

1. For low-frequency input power levels from 6 to 50 watts connect the "hot" side of the 70-volt line to the appropriate tap on the

A102A Transformer (50-6W) (Figure J). Connect the ground side of the 70-volt line to the COM power tap of

A102A, and the COM impedance tap of the

the A102A to the negative (phone plug sleeve) terminal of the nect the 16-ohm impedance tap of the

SR108 LOW FREQ lnput Jack. Con-

A102A to the positive (phone plug tip) terminal of the SR108 LOW FREQ lnput Jack.

2. For the high-frequency 70-volt input (any power level up to 50 watts), connect the

"hot" side of the 70-volt line to the power tap of a second A102A Transformer offering the most suitable balance of high- to low-frequency sound. First

try the high-frequency power tap that is

onehalf the power of the low-frequency tap. Connect the ground side of the 70-volt line to the

A102A COM power tap. Connect the A102A 16-

ohm impedance tap to the positive (phone plug tip) terminal ot the Jack, and the

A102A COM impedance tap to the

SR108 HlGH FREQ lnput

negative (phone plug sleeve) terminal of the SR108 HlGH FREQ lnput Jack. Listen to program material through the sound system and adjust the high-frequency power tap if a different

high-frequency/low-frequency

balance is

desired.

Phasing (Polarity)

The

SR108 is phase-wired for biamplified operation as follows: A positive voltage applied to a LOW FREQ lnput Jack tip produces a positive sound pres-

sure, and a positive voltage applied to a HlGH FREQ lnput Jack tip produces a negative sound pressure. This conforms to the requirements of the internal

passive crossover network, and to the design of most

two-way speaker systems.

When using the

SR108 with an external active

electronic crossover network and separate power am-

plifiers, the following considerations should be given to phasing: When a Shure Model

SR106 Electronic

Crossover and identical high- and low-frequency power

amplifiers (Shure Model

SR105 or equivalent) are used, the phasing is correct. A different crossover network or dissimilar high- and low-frequency power amplifiers may be used as long as all low-frequency sections are in phase with one another and all high-frequency sections are in phase with one another. A potential problem exists only when there is a phase reversal between the high- or low-frequency sections of the speaker systems in use. To check for possible

outof-phase condition, the following listening test should be performed on both high- and low-frequency sections of the ing two

SR108's. The test should be made feed-

SR108's at a time (using one SR108 as a phase

reference) with the same program material (vocal material, or pink noise). After connecting the equipment, turn on the sound system and adjust for a moderate level. Disconnect the high-frequency driver input ca-, bles. Stand approximately mid-way between the two SR108's and listen to the program material while reversing the "hot" and common leads to one of the low-frequency speaker sections. (This may be accom-

plished by wire-reversing or by

simple cross-wired, double-pole, double-throw switch.) Use the connection that gives a localized sound, centered between the SR108's; this is the correct phase connection. A diffuse, directionless sound indicates improper phasing.

Reconnect the high-frequency driver sections, disconnect the low-frequency sections, and perform the same test as above. Correct phasing will provide a

localized sound, centered between the

SR108's; incorrect phasing is indicated by the sound appearing to come predominantly from one from one

SR108 to another as the listener moves

SR108, and to shift

around the audience area. NOTE: In a mixed system

(both conventional full range and biamplified) the highfrequency driver sections are normally out of phase with one another. Therefore, the biamplified

high-fre-

quency signals must be reversed to assure that the

high-frequency drivers of all

SR108's are in phase.

Wiring

For biamplified operation, a second cable must be obtained (Shure RKC4 or equivalent). When using other cables, or when using extension cables, the

wire gauge constraints shown in Figures K and L

apply. As in conventional full-range operation, the

second

used for additional, parallel-connected SR108's.

HIGH and LOW FREQ lnput Jacks may be

biamplified

BASIC OPERATING HINTS

Should any difficulty be encountered in SR108 ope-

ration, the problem may often be traced to some

simple source such as an

The following is offered as a basic guide to problems

of this sort. Symptom:

Check: 1. Check inputs and outputs of all equip-

Symptom: Poor or no high-frequency output (normal Check:

Symptom: Poor or no low-frequency output (normal

Check: 1. If symptom appears only when LOUD-

SERVICE

Speaker Servicing

1. To measure dc resistance of high-frequency

SR108 is "dead" (no output)

ment driving

2. Check interconnecting cables and connectors.

3. Check to see that LOUDSPEAKER OPERATION Switch position corresponds to desired operating mode.

low-frequency output)

1. Check setting of LOUDSPEAKER OPERATION Switch.

2. If symptom appears only when LOUDSPEAKER OPERATION Switch is in AMP position, check output of equipment

driving high-frequency drivers.

Check high-frequency response of program material.

high-frequency output)

SPEAKER OPERATION Switch is in AMP position, check output of equipment driving low-frequency speakers.

2. Check low-frequency response of program material.

INSTRUCTIONS

driver assembly (LOUDSPEAKER SWITCH in any position), first remove speaker cables. Remove

10 Phillips head screws securing upper rear panel to enclosure. Remove panel and disconnect wiring harness on printed circuit board (see Figure solder high-frequency driver leads from inductor L2 and measure dc resistance of high-frequency

driver assembly ance of assembly should be between 12.5 and

14.5 ohms.

To measure dc resistance of each high-frequency driver curing high-frequency driver assembly support

bracket used) and remove bracket. Do not permit

frequency driver assembly to drop when bracket is removed. Carefully withdraw high-frequency

driver assembly (drivers and throat adapter as-

sembly) from compartment. Disconnect one lead between the four high-frequency drivers. Measure resistance of each high-frequency driver

voice coil. Each driver should measure between

12.5 and 14.5 ohms. Replace any defective drivers as described in High-Frequency Driver

Replacement.

(LS7-LSlO), remove five bolts se-

(318" and 9/16" socket wrench may be

er.ror in interconnection.

SR108.

BI-

(PI) from its socket (J7)

(LS7-LS10). Total dc resist-

M).

Un-

high-

2. If above tests do not locate defective high-frequency driver, check for voice coil rubbing or

binding by driving each driver with a test signal

(4V

max.) from a sweep oscillator and amplifier covering the frequency range from 2600 to 10,000

Hz.

WARNING

Sound pressure levels generated by this test may be damaging to your hearing. Aim drivers away from listeners and toward sound-absorbent material (curtains, blanket, etc.). Carefully adjust test signal amplitude to avoid unnecessarily high sound pressure

levels for prolonged periods.

Sound from high-f requency drivers should be

clean and free from buzzes or rattles which may

indicate driver failure. Replace any defective drivers as described in High-Frequency Driver Replacement.

To measure dc resistance of low-frequency speakers, connect an ohmmeter between tip and sleeve connections of FULL-RANGE Jacks J1 or J2 (LOUDSPEAKER OPERATION Switch in -4, -2, tween tip and sleeve connections of LOW BlAMP SPEAKER OPERATION Switch in BlAMP position). The FULL-RANGE resistance reading should be between 11.25 and 13.35 ohms, and the BlAMP reading should be between 11.25 and 12.75 ohms. Readings outside these limits indicate possible low-frequency speaker failure. To measure dc resistance of each low-frequency speaker screws securing lower rear panel to enclosure. Remove rear panel and rest it on floor, taking care not to stress input jack wiring. Using ohmmeter, measure resistance of each low-frequency speaker coil. A clicking sound will be made by a "good" speaker when ohmmeter is connected

or disconnected. Each low-frequency speaker should measure between 7.5 and 8.5 ohms with speaker leads disconnected. Replace any speak-

ers found defective.

If above tests do not locate defective low-fre-

quency speaker, check for voice coil rubbing or

binding by first disconnecting lead between two top low-frequency speakers. Set sweep oscilla-

tor and amplifier to produce test signal (8V max.)

and sweep each speaker over the frequency

range of 50 to 2600 Hz.

OPERATION lnput Jacks J3 or J4 (LOUD-

(LS1-LSG), remove 26 Phillips head

0 or +2 position), or be-

lnput

FREQ/

WARNING

Sound pressure levels generated by this

test may be damaging to your hearing. Aim drivers away from listeners and toward sound-absorbent material (curtains, blanket, etc.). Carefully adjust test signal to avoid unnecessarily high sound pressure

levels for prolonged periods.

amp1 itude

Sound from low-frequency speakers should be clean and free from buzzes or rattles which may indicate speaker failure. Replace any speakers found defective. Be sure to

resolder discon-

nected leads and fasten all hardware securely

to avoid rattles.

High-Frequency Driver Replacement

To replace a high-frequency driver, follow these steps:

1. Disassemble the high-frequency driver assembly as described in Speaker Servicing.

2. Unsolder leads from driver terminals.

3. Remove three 6-32

in. screws securing

high-frequency drivers to gasket and mounting

plate of throat adapter assembly.

Replace driver diaphragm and voice coil assem-

bly as described in High-Frequency Driver Dia-

phragm and Coil Assembly Replacement.

Carefully place repaired or new high-frequency driver in position over gasket and mounting

plate, taking care to line up holes in driver

over holes in gasket and mounting plate. Be sure that driver terminals are in same position

as when removed.

6. Replace three 6-32

1 % in. screws, and tighten high-frequency driver assembly in upper enclosure compartment.

Resolder removed driver leads.

8. Reassemble upper rear panel to enclosure and fasten securely to avoid rattles.

High-Frequency Driver Diaphragm and

Coil Assembly Replacement

The high-frequency driver is attached to the mount-

ing plate with three 6-32

Figure

for further identification of driver components.

1% in. screws. Refer to

Replace the diaphragm and coil assembly in the

high-frequency driver as follows:

1. Disassemble high-frequency driver assembly from enclosure as described in Speaker Servicing above.

2. Unsolder leads connected to driver terminals.

3. Remove screws securing driver to mounting plate.

CAUTION

Do not allow driver to drop when removed.

Prepare clean work area, free of drafts and metallic dust and chips. Cover work area with clean kraft paper or newspaper.

Place driver on work surface. With three 6-32

1% in. screws securing driver to mounting

plate previously removed, remove'phasing plug.

6. Remove diaphragm and coil assembly by lifting upward. This is a snug fit and a gentle prying force may be required.

Clean voice-coil gap in magnetic structure as follows: Insert strip of masking tape into

voicecoil gap with adhesive side outward. Draw tape around gap several times to provide good

wiping action. Repeat process with new piece

of tape with adhesive side facing inward.

MOUNTING PLATE

ADAPTER ASSEMBLY

DIAPHRAGM AND COlL ASSEMBLY

VOICE-COIL GAP

STRUCTURE

GASKET-

MAGNETIC

CLEARANCE HOLES

161*

LOCATOR

CLEARANCE HOLES 131

PINS 131

FIGURE N.

DIAPHRAGM AND

COlL ASSEMBLY REPLACEMENT

CAUTION

The diaphragm and coil assembly is a delicate part. Do not touch voice coil and bobbin, or allow it to come in contact with work surface, tools, etc. If assembly is placed on work surface, rest it on diaphragm with voice coil upward.

8. Assemble new diaphragm and coil assembly to to magnetic structure with coil facing magnetic structure. Locate three small holes in diaphragm and coil assembly over locator pins in magnetic structure. Three large holes in diaphragm and coil assembly will line up with holes in magnetic structure.

Assemble driver and phasing plug to mounting

plate. Position mounting holes so that solder

terminals are outward and do not interfere with

adjacent drivers.

10. Replace three screws and tighten them securely but do not over-tighten.

Reassemble the high-frequency driver into the

Resolder driver leads.

highfrequency driver assembly and replace assembly in speaker enclosure.

Overvoltage Attenuator Network Threshold Adjustment

The protection circuitry of the SR108 high-frequency

driver array contains a 2000-ohm rheostat

(R10) which may under certain conditions (component replacement, extreme shock, etc.) require readjustment. This may be accomplished as follows.

1. Turn rear-panel LOUDSPEAKER OPERATION Switch

(Sl) to BlAMP position.

2. Remove upper rear panel as described in Speaker Servicing above.

3. Unsolder high-frequency driver assembly leads (black and green) from inductor assembly L2, and place a dummy load (16 ohms, 50 watts

minimum) across L2.

4. Connect an ac voltmeter

(Simpson 260 or equi-

valent) across dummy load.

5. Apply a across one

kHz ac voltage from a power amplifier

HlGH FREQ/BIAMP OPERATION Input Jack (J5 or J6). Slowly increase voltage until 28

Vac is reached. Relay K1 should open,

as indicated by ac voltmeter reading suddenly

dropping to approximately 13 not, adjust rheostat

R10 until relay K1 operates

as input voltage reaches 28

Vac. If it does

Vac. Remove input

voltage to release relay.

6. Remove ac voltage, disconnect dummy load and voltmeter, and

resolder high-frequency driver leads. Replace rear panel and tighten all screws securely to avoid rattles.

Radial Horn Replacement

To replace the

follow these

Remove 10 #8 Phillips head screws securing

SR108 high-frequency radial horn,

stem:

horn to front of enclosure.

2. Lift horn outward from front of enclosure, insert new horn, and replace 10 Phillips head screws.

3. Replace foam screen in horn throat, apply BOND (or equivalent) cement around edges to

hold it in place. Make sure all hardware is tightly fastened to avoid rattles.

Grille Assembly Replacement

To remove and replace the

SR108 front-panel grille

assembly, follow these steps:

1. With

SR108 lying flat on a firm surface, use a

short length of wood (2 in.

4 in. is recom-

mended) to apply firm, steady pressure at center of grille approximately one-third distance from top.

2. As grille is pushed back, edges will appear in left and right slots. Use a screwdriver or knife

to gently pry edges of grille up over edge of

slot on either left or right side.

3. Begin removing grille assembly from top, taking care not to scratch enclosure with edge of grille.

PLIO-

Wheel Assembly Replacement

To replace a wheel or other parts of the

SR108

wheel assembly, follow these steps (see Figure R):

Place SR108 face downward on flat surface and remove lower rear panel as described in Speaker Servicing.

3/4

2. While holding wrench, insert a

assembly

capscrew and unscrew capscrew from

in. locknut with a socket

in. Allen wrench in wheel

the assembly.

3. With locknut, flat washer and

capscrew removed,

wheel and bushings may now be removed.

When reassembling wheel assembly, be sure to replace flat washer before tightening locknut.

Tighten

capscrew and locknut firmly.

5. Install back panel and tighten securely to avoid

rattles.

Model

RKC149 Crossover Assembly

A complete crossover assembly may be obtained

from Shure Brothers Inc. as Model

RKC149. This as-

sembly provides complete facilities for high- and

low-frequency signal separation, and overvoltage protection. A general description of the crossover assembly is included in the CIRCUIT DESCRIPTION section, and biamplified operation is described in the BlAMPLlFlCATlON section.

The Model

in Table 1 (refer to Figures

RKC149 consists of the components listed

and P, and the Replace-

ment Parts List).

The LOUDSPEAKER OPERATION switch

(Sl) con-

tains the following settings:

Position 1 (full CCW): Position 2: Position 3: FULL RANGE Position 4: FULL RANGE

Position

(full CW):

FULL RANGE -4 dB FULL RANGE -2 dB

0 dB

BlAMPLlFlED

Connector PI is a nine-pin connector in which eight

pins are connected as follows (see Figures M and P):

Pin 1: FULL RANGE common input

LOW FREQ common input

Low-frequency speaker common output Pin 2: LOW FREQ "hot" input Pin 3: Pin

HlGH FREQ "hot" input

HIGH FREQ common input Pin 5: Low-frequency speaker "hot" output Pin 6: FULL RANGE "hot" input

High-frequency driver common output Pin 8: High-frequency driver "hot" output

WARNING

Grille assembly is under tension and effectively presents a spring-loaded rough edge as it is removed. Take care not to handle assembly at edges during removal.

4. As grille edge near top comes free, move hand applying pressure and screwdriver edge downward to free remainder of grille.

Replace new grille assembly by centering it in enclosure, and applying pressure at center until grille assembly "pops" into slots.

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 in-

cludes all parts and labor. SHIPPING INSTRUCTIONS

Carefully remove the defective part without damag-

ing the unit, repack it, and return it prepaid to the

factory. If outside the United States, return the part

your Authorized Shure Service Center for repair.

The part will be returned to you prepaid.

For service or instructions on the complete speaker

system or enclosure, contact your Authorized Shure

Service Center or the Shure Factory.

CROSSOVER

\SPEAKER

CABINET

ASSEMBLY

SWITCH S1

Item

Qty.

2 2

INDUCTOR

ASSEMBLY

Shure Part No.

90A2451

90A2112

90A2070

30A1002B

30H1035A

30A775

Table

FIGURE P. RKC149 COMPONENTS

Crossover

Component

Crossover Assembly (Al, S1)

Inductor Assembly (L2 with terminal board)

Connector Assembly leads

Carriage Bolt, Aluminum, 2" Screw, Round Head, Type A,

No. 10 Hex Nut, No. 10-24NC-2

Assembly

(PI with

CONNECTOR ASSEMBLY

Components

Use

Separates high and low frequencies, and provides overvoltage protection

With C2, provides high-frequency driver protection

Connects input connectors and speakers to

Secures A1 and L2 to speaker cabinet

Secures A1 to speaker cabinet

Secures

A1 and L2 to speaker cabinet

9 10 11

2 1

2 5

30A964A

30A136 30A960A 31A1199 80A255

Hex Locknut, No.

32NEF-2B Lockwasher, Lockwasher, Spacer, Aluminum, 1" Cable Tie, Nylon

34-

Y2"

Secures

Secures Secures Secures Secures leads of

S1 to speaker cabinet

A1 and L2 to speaker cabinet S1 to speaker cabinet A1 to speaker cabinet

PI wiring harness

REPLACEMENT PARTS LIST

(See

Figures

and

Reference

Designation

A1 A2

Dl -D4 J1-J6

K1 L1,

LS1 -LS6

LS7-LS10

M PI

MP2

M P3 M P4 MP5 M P6 M P7

MP8

MP10

Replacement

No.*

Kit

RKC132

RKC21

RKC68

RKC136

Q~Y.

4 1

Part No.

90A2063 90A2068

90A2064

90E1375

94A1182

50A71

50871

86 K630

86A404 95B446

90A2074 80A280 95A640 80A276

80A278 80A275

60A57

90A2196 48E35A 39A422 90A2062 11A141 53A1335 60A58 39A387 53A1376A

Replacement Kit Consists

Description

Crossover Network Assembly High-Frequency Driver Assembly

(LS7-LS10, A3) High-Frequency Driver Throat Assembly

(without drivers)

Jack Panel Assembly

(including connectors)

High-Frequen~y Driver Diaphragm

and Coil Assembly

Capacitor, Metallized Mylar, Non-polarized,

,F,

4.7 Capacitor, Metallized Mylar, Non-polarized,

2.2 Capacitor, Electrolytic, 50 ,F,

100 WVdc Silicon Rectifier, 100V, Y2A Connector, Phone Jack, 2-Conductor,

Open Circuit (Switchcraft 11)

Socket Assembly, 9-Contact

Relay, SPDT, 24 Vdc Inductor, 1 8-Inch Loudspeaker

(interchangeable parts) High-Frequency Driver (see A5 for

replacement diaphragm and coil assembly)

Speaker System Enclosure Assembly (with Lower Rear Panel; without Upper Rear Panel, Horn, Grille Assembly, Crossover Assembly, High-Frequency Driver Assembly, Switch Panel Assembly, Wheel Assemblies, Low-Frequency Speakers, Jack Panel Assemblies, Fiber Glass, Caution Plate, and Rear Panel Trim, and Hardware)

Radial Horn Assembly Front-Panel Rail Nameplate

Grille Assembly Fiber Glass (Sound Absorber)

Rotary Switch Panel (without Switch)

Upper Rear Panel Caution Plate Support Bracket, High-Frequency

Driver Assembly

250 WVdc**

,F,

250 WVdc**

mH, 0.6 Ohms

Of:

Front-

*Parts listed as

Any orders received for piece parts where

"Selected for low dissipation factor.

RKC

Kits

should be ordered by that number.

RKC

Kit number is shown will be shipped in

RKC

quantities.

REPLACEMENT PARTS LIST

(Continued)

Reference

Designation

MPl1 MP12

MP13 MP14 MP15

MP16

MP17

MP18

MP19

MP20

MP21

MP22

P1 R1 R2 R3 R6 R7

R8,

R9 R10 S1

Replacement

Kit No.*

RKC4

Qty.

Part No.

95A638 95A641

48A47A 36A336 30C806C

30D832D

30H832D

30A1007A

30A1008A

31 A1 224A

53A1334A

90A2155A

90A2070 45HC758C 45HC508C 45HC408D 45HC750D 45CC470B

45EC400G 45A40 55A106

9081373

Replacement Kit Consists

Description

Wheel

Cable Compartment Strap and Socket

Assembly

Rail Foam Screen Phillips Finishing Head

Cutting Screw, Black, #8, 1 in. (Horn, Upper and Lower Rear Panels

to Enclosure)

Phillips Flat Head Wood Screw, #6,

in. (Front-Panel Rail to

Enclosure)

Phillips Flat Head Wood Screw, #6,

in. (Rear-Panel Rails to

Lower Rear Panel)

Capscrew, 13UN-3A Thread, 39'2 in. long (Wheel Assembly)

Locknut, in. (Wheel Assembly)

Wheel Bushing, Steel, 38.1 mm OD (Wheel Assembly)

Washer, Steel, 34.9 mm (1

(Wheel Assembly) Front Bracket Assembly,

High-Frequency Driver Assembly Plug Assembly, 9-Pin

Power Resistor, 7.5 Ohms, 7W, 10% Power Resistor, 5 Ohms, 7W, 10% Power Resistor, 4 Ohms,

Power Resistor, 75 Ohms,

Resistor, Carbon Composition, 47

Ohms,

Power Resistor, 40 Ohms,

Rheostat, 2k, 3W Switch, Rotary, 6-Pole, 5-Position,

LOUDSPEAKER OPERATION

15.2m (50-foot) Cable Assembly

with Male Phone Plugs

Y2W, 10%

in., Black,

Y2-13UN-2B Thread,

Of:

Thread-

V'z-

in.) OD

low,

22W, 10%

(1% in.)

10%

'Parts listed as RKC Kits should be ordered by that number.

Any orders received for piece parts where RKC Kit number is shown will be shipped in RKC quantities.

FIGURE

PRINTED CIRCUIT BOARD PARTS LOCATION

2063-6/595-5

ARCHITECTS' AND ENGINEERS' SPECIFICATIONS

The Speaker System shall be an extended range, two-way speaker system designed for high sure-level reproduction of wide frequency range program material in sound reinforcement applications. The Speaker System shall utilize six 8-inch cone-type speakers with a total speaker cone area of 1097 cm2

(170 in2) and four high-frequency drivers. Pressure

sensitivity of the Speaker System shall be an EIA

rating of 54 dB at

valent to 102 dB at

The sound power distribution shall be nominally

uniform over a 140" angle in the horizontal plane and a 90" angle in the vertical plane. The Speaker System enclosure shall be a bass reflex design to provide extreme low-frequency enhancement, with quency speakers column-mounted in a horn-loaded, front-ported enclosure, and high-frequency drivers

coupled to a single radial horn.

The frequency response of the Speaker System shall be uniform and peak-free from 40 Hz to 15,000 Hz when driven by a constant-voltage amplifier and radiating into an acoustical half-space.

In conventional, full-range, single-amplifier operation, the continuous power rating of the Speaker System shall be 200 watts maximum (57-volt source)

and the nominal impedance shall be 16 ohms. In biamplified operation, the low-frequency section shall accept up to 200 watts of program material and the high-frequency section up to 100 watts.

The six low-frequency speakers shall be wired in

a series-parallel configuration and mounted in a

column configuration against the front baffle of the Speaker System. The four high-frequency drivers shall be wired in a series-parallel configuration at the top and coupled to a throat adapter assembly

9.2m (30 feet) from 1 milliwatt (equi-

1.2m--4 feet-with a I-watt input).

sound-pres-

low-fre-

connected to a single radial horn. The high-frequency drivers shall be wired through an integral passive crossover network with a crossover frequency of 2600 Hz. A rear-panel LOUDSPEAKER OPERATION Switch shall provide four selectable high-frequency

level positions of -4,

tional full-range operation, and a

biamplified operation. The inputs shall consist of a

pair of parallel-wired phone jacks for (1) conventional full-range operation, (2) low-frequency biamplified operation, and (3) high-frequency biamplified operation.

The Speaker System enclosure shall be 15.9

in.) wood construction covered with black, textured, scuff-resistant vinyl, and have anodized, solid aluminum rear-panel rails. The enclosure shall have an

integral rear-panel handle and two heavy-duty hard

rubber wheels for mobility, and shall contain a cable storage compartment at the top rear. The radial horn shall be of high-density, structural urethane foam. A

plug-in The Speaker System shall measure 1730 mm in height, 495 19Y2 in. X 20% in.). The weight, including the sup-

plied cable, shall be 64.5 kg (142 Ib).

System shall be -7°C to 43°C (20°F to 110°F). The storage temperature range shall be -29°C to 71°C (-20°F to 160°F). The Speaker System shall meet all specifications when operated within the operating

temperature limits.

specifications, or having a sealed cabinet which prevents internal inspection and servicing, shall be

deemed unacceptable under this specification. The

Speaker System shall be

15.2111 (50-foot) speaker cable shall be supplied. in width, and 517 mm in depth (68% in.

The operating temperature range of the Speaker

Any Speaker System not meeting all of the above

2, 0 and +2 dB for conven-

Shure Model SR108.

BlAMP position for

Shure SR108 User Guide

Specifications and Main Features

Frequently Asked Questions

User Manual