Specifications

ManualsBrandsShure ManualsAmplifierSR10

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. The test should be made feeding two

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

erence) with the same program material (vocal ma-

terial, or pink noise). Connect the

SR106, power am-

plifiers,

SR108's, and program input equipment.

Wiring

The cables used to connect the SR108 should be at

least 18-gauge and rubber-jacketed. Determine the ap-

proximate distance from the amplifier to the

SR108

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:

CAUTION

Do not interchange high- and low-frequency

speaker cables. Damage to high-frequency

drivers from high-level, low-frequency sig-

nals may result.

Gauge

AWG 18

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

cross-

wired, double-pole, double-throw switch.) Use the

connection that gives a localized sound, centered be-

tween the

SR108's; this is the correct phase connec-

tion.

diffuse, directionless sound indicates improper

phasing.

AWLlCEI-TO-SPEIKER DISTANCE VEETl

AMPLIFER-TO-SPEAKER DISTANCE IYLTLRSI

FIGURE

RECOMMENDED WIRE GAUGE:

DIRECT-COUPLED AMPLIFIER OUTPUT

Belden

8460, 8461,

9720, 8452

Reconnect the high-frequency driver sections and

disconnect the low-frequency sections. Perform the

same test as above. Correct phasing will provide a

localized sound, centered between the

SR108's; in-

correct phasing is indicated by the sound appearing

to come predominantly from one

SR108 and to shift

from one

SR108 to another as the listener moves

around the audience area. NOTE: In a mixed system

(both conventional full range and biamplified) the

high-frequency driver sections are normally out of

phase with one another. Therefore, the biamplified

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

SR106 high-frequency output.

Area (mm2)*

0.8

AWG 16

y28471,

1.3

AWG 14

8473

2.1

AWG 12

8477 3.3

To avoid frequency cancellations, poor coverage,

dead zones, etc., resulting from improper speaker

phasing, the

SR108's must be wired in proper polarity.

The cables listed above are color-coded to ensure

that identical connections are used for each

amplifier-

SR108 hookup. Note that even common 18-gauge lamp

cord ("zip cord") is phase-coded with a ribbed outer

jacket, color-coded threads, or tinned and untinned

conductors.

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

supplied with the

SR108 in conventional full-range

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

panel.

AWG 10

When wiring the SR108 for biamplification operation,

a second cable (Shure

RKC4) must be obtained to

provide connections to both the

HIGH and LOW FREQ

input phone jacks. The same wire gauge constraints

listed above for conventional full range operation apply

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

SR108 high- and low-frequency inputs are

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

ever, the wire gauge of the common wire should be

one size larger than the gauge indicated in Figure

5.3

When wiring the

SR108's consideration should

given to positioning of the cables. While most local

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

SR108.

*Cross-section of American Wire Gauge (AWG)

Placement

The SR108 Extended Range Speaker System is pri-

marily designed for free-standing operation. In posi-

tioning for optimum sound coverage, care must be

taken to locate the

SR108's on stable surfaces and

away from areas where the movement of performers,