Handbook for Sound Engineers

Sound System Design 1293

will break after the repeated flexing of portable usage.
Shields should be braided wire, not foil, for the same
reason. Cable for permanently installed systems, on the
other hand, can utilize foil shields. In addition, while a
tough, rubberized outer sheath is desirable for portable
cable (like microphone cable), a smooth vinyl-type
sheath will benefit the permanent system installer, since
it pulls through conduit more easily.

34.5.1.4.2 General Notes on Connectors

There are only a few types of connectors in general use
in commercial and professional sound systems, as
shown in Figs. 34-54 and 34-55. The most common of
these are discussed here.

34.5.1.4.3 XLR-Type Connection

The term XLR was first used by the Cannon Company
but has almost become a generic label for these
high-quality audio connectors, now made not only by
Cannon but also by Switchcraft, Neutrik, ADC, and oth-
ers. XLRs are the connector of choice for microphones
and any balanced low-level or line-level audio signal as
well as AES/EBU digital connections.

34.5.1.4.4 Phone Plugs

The term phone comes from the telephone industry,
which normally used a type of phone plug in its early,
nonautomated switchboards. Recording studio and other
patch bays are close relatives of these telephone switch-
boards and often use a three-conductor variety of phone
plug. The most common type of phone plug used in pro
audio has a ¼ inch diameter shank and comes in
two-wire (known as tip/sleeve, or T/S) and three-wire
(known as tip/ring/sleeve, or T/R/S) versions. The
¼ inch phone plugs are commonly used for instrument
amplifiers and hi-Z microphones and sometimes for
portable loudspeaker connectors. Unlike XLRs, which
are almost invariably high quality, the quality of com-
mercially available phone plugs can vary widely.

34.5.1.4.5 RCA-Type Phono Plugs

Note the term phono not phone, indicating that these
plugs got their start on phonographs manufactured by
the original RCA company. Phono plugs, or RCAs, are
used primarily on hi-fi equipment but may be used to
adapt a hi-fi tuner or cassette machine, for example, to
an input of a professional mixer. Phono plugs, however,

are fragile and do not make good general-purpose

pro-audio connectors. Higher-quality phono plugs are

used as the coaxial digital audio connectors on con-

sumer equipment.

34.5.1.4.6 Barrier Block Connectors

Professional audio products continue to get smaller

while simultaneously adding more inputs and outputs.

Manufacturers have responded by adopting miniature

barrier block connectors, often called Phoenix connec-

tors or Euro-Block connectors, for inputs and outputs.

These connectors use a screw to capture individual bare

wires in a small terminal hole.

34.5.1.4.7 CAT 5 Connectors

CAT5 connectors, also known as RJ45 connectors, are

used for Ethernet networking and related digital audio

connectors, Fig. 34-56.

Figure 34-54. Various audio connectors.

A. XLR.

B. Phone plug.

C. RCA (phono).

D. Miniature barrier block or Euroblock.