Obstructions - PSB the CustomSound Series Installation Manual

Increasingly, different source signals may be provided to different
rooms/zones/speakers—at the same time. Increasingly, control systems allow
adjustments from locations different/remote from the signal sources, switching, tone
control, and amplification. Some rectangular models include a knockout in the baffle
into which an infrared signal remote receiver can be installed. With increasing levels
of multi-zone and remote control sophistication, it is increasingly desirable to have a
simple volume control local to speakers distant from the main equipment. This
control—for volume up and down and off and on—may be in a small, freestanding
box or flush-mounted in a wall.
Overall, a musical source—audio or video—is fed first through a preamplifier with
switching and tone controls—and then through a power amplifier and onwards to
each speaker. The preamplifier provides a level of tone controls—bass, treble, and
balance left to right. Surround processors, operating between the preamplifier and
amplifier stages, can provide surround decoding and another level of channel
balancing—front left, right, and center; surround left and right; and subwoofer. An
equalizer before the amplifier can provide some adjustment to smooth response for
field conditions and preferences. Multiple amplifiers may be used for multiple zones
and speaker loads.
D. Obstructions
With tentative speaker locations determined, potential obstructions must be
explored and the conflicts resolved: Structural; Mechanical—Electrical, Plumbing,
and HVAC; and Furnishings.
Temporarily mark and view tentative speaker locations and the existing construction
carefully to determine the existing structure and mechanical installations and
potential obstructions. Adjust the speaker layout, the furnishings, the mechanical,
and/or the structural to resolve the conflicts. Layout, review, and resolution on
building plans can be a very efficient process. However, some conflicts will inevitably
appear and need to be resolved as actual conditions are reviewed and as
installation proceeds.
Most typically and very basically, residential walls are constructed of wooden
studs—nominally 2" x 4", but measuring 1½" x 3½" (sometimes, particularly on
exterior walls 2" x 6", measuring 1½" x 5½") and normally located on 16"
centers—with 14½" between studs. This stud pattern usually begins from one,
exterior corner and results in a smaller than normal spacing at the other corner. The
full height "common" studs extend from a flat "sole" plate on the floor to a "top" plate
(often doubled) at the top of the wall. Top headers of doubled 2" x 4"s (or larger) are
placed on edge spanning over doorways and windows, and doubled sill headers run
under window openings. "Trimmer/jack" partial studs run under the ends of all
headers, doubled against full studs against the ends of all headers. Shorter partial
"cripple" studs run over headers to the top plate and under sills to the bottom
plate—at nominal spacing. Blocking may be between studs about mid-wall, behind
cabinets and other fixtures mounted to the wall, and over and under ductwork
through the stud cavity. Electrical receptacles and switches are mounted in electrical
boxes, usually mounted to a stud. Removing electrical cover plates in finished walls
is a good initial step to determine where studs are located.
Floors typically are constructed of wooden joists—nominally 2" x 8" or deeper, but
measuring 1½" x 7¼" or deeper and normally located on 16" centers (but not
uncommonly on 12" centers). Roofs typically are constructed of wooden
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