Specifications

FIGURE L.
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
SR108's should be
secured with rope, cable or strapping to maintain
their physical positions and prevent accidents.
If it becomes necessary to elevate the
SR108 for
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
SR108.
For elevations greater than three feet, it is important
to note that the
SR108 is not designed for simple chain,
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, archi-
tect or engineer should be consulted to provide build-
ing 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.
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
of the
SR108 plus the platform.
If the
SR108 is to be used on a constant-voltage
system, a Shure
A102A 70-Volt Transformer must be
connected between each amplifier and
SR108. If the
A102A Transformer is used, it should be located as
close to the
SR108 as possible. If mounted to the rear
of the
SR108, the transformer adds approximately 82
mm
(3Y4 in.) in depth and 2.95 kg (6 Ib) in weight to
the
SR108.
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
SR108's with minimal differences in
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
SR108's are not covering
that
area; or that the SR108 speaker wires are con-
nected out-of-phase. Proper phasing (polarity) may be
readily determined by checking the connections to
the phone jacks on each
SR108 to make sure they
are the same; inadequate coverage generally requires
repositioning the
SR108's.
Should a dead area be encountered, it should be
carefully examined to determine if the problem can
be corrected without resorting to auxiliary speakers.
BlAMPLlFlCATlON
If suspended mounting, using chains or cables at-
The data in this section relates only to the use of
tached to beams or girders, is an absolute necessity,
the
SR108 in the biamplified mode. Some portions of
a platform must be devised which will be capable of
data in preceding sections are repeated here to pro-
both supporting the
SR108 and retaining the chains
vide a comprehensive section on biamplification.
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