Specifications

ManualsBrandsShure ManualsAmplifierSR10

CAUTION

covering a wide area, each SR108 should be posi-

tioned 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 ob-

ject is to provide maximum area coverage (audience)

with the available floodlights

(SR108's). At the same

time, care must be taken to avoid illuminating reflec-

tive 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 prob-

lems, 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 con-

sole. 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

Full-Range Direct-Coupled Operation

The

SR108 is designed to accept program material

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 sig-

nals. It should be pointed out that the various speaker

input jack pairs are for paralleling additional speakers

and

not

amplifiers.

CAUTION

Amplifier damage may result if two ampli-

fiers 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 con-

stant-voltage, 70.7-volt line by using a 70-volt trans-

former 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 pro-

duces the desired power level. Connect the high-fre-

quency 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

CONNECT

LOUDSPEAKER

POWER AMPLIFIER

WITH

OUTPUT

POWER

VOLTAGE

RATING

GREATER

THAN

THE

VALUES

INDICATED

BELOW.

SEE

INSTRUCTION

MANUAL

FOR

ADDITIONAL

INFORMATION.

LOUDSPEAKER

CONNECTION

INPUT

HIGH FREO

AMP

FULL RANGE

'OW

FREa

BIAMP

PARALLEL

I_I

CONVENTIONAL FULL-RANGE OPERATION

AMPLIFIER OUTPUT SHOULD NOT EXCEED

100

WATTS

;,"As

16 OHMS

CONTINUOUS

POWER

TO 16 OHMS

PARALLEL

200

WATTS

400

WATTS

LOW FREO SECTION BIAMP OPERATION

HIGH FREO SECTION

CONTINUOUS

POWER

OHMS

BIAMP OPERATION

OHMS

IXlERNAL LOW

P1SS

CROSSOVER NETWORK

EXTERNAL

HIGH

PASS CROS1016. N11WORK

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

400

WATTS

800

WATTS

WARNING

THIS SPEAKER CAN PRODUCE SOUND PRESSURE LEVELS WHICH MAY

CAUSE PERMANENT HEARING DAMAGE AFTER PROLONGED EXPOSURE.

CONTINUOUS

POWER

TO 4 OHMS

FIGURE

SPEAKER INPUTS

VOLTS

RMS

VOLTS

RMS

through the sound system and adjust the high-fre-

quency power tap if a different

high-frequency/low-

frequency balance is desired.

CONTINUOUS

OUTPUT

VOLTAGE

VOLTS

Phasing (Polarity)

The

SR108 is phase-wired for conventional, full-

range 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

HlGH

FREQ/BIAMP OPERATION lnput Jack tips produces

a negative sound pressure. This conforms to the

requirements of the

SR108 internal passive cross-

over network, which provides the proper phase rela-

tionships at the crossover frequency.

When using the

SR108 in biarnplified operation

with an external active electronic crossover network

and separate power amplifiers, the following consid-

erations should be given to phasing: When using a

Shure Model

SR106 Electronic Crossover and identi-

cal power amplifiers (Shure

SR105 or equivalent) to

power an

SR108, the phasing is correct. Dissimilar

high- and low-frequency power amplifiers may be

A102A

POWER

PEAK

"HOT"

-I

02=w

12W

70.7

LlHE

SYSTEM

GROUND

COM

50-6 WATTS

FIGURE

70-VOLT OPERATION