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Chapter 2: Connections
RA150/300/500 Reference Manual 15
CABLES
Use only high quality cables when interfacing
equipment with the RA150/300/500. These should
be good quality shielded cables with a stranded (not
solid) internal conductor. Although quality cables
cost more, they do make a difference. Route cables
to the RA150/300/500 correctly by observing the
following precautions.
• Do not bundle audio cables with AC power
cords.
• Avoid running audio cables near sources of
electromagnetic interference such as
transformers, monitors, computers, etc.
• Do not place cables where they can be stepped
on. Although stepping on a cable may not cause
immediate damage, it can compress the
insulation between the center conductor and
shield (thus degrading performance) or reduce
the cable’s reliability.
• Avoid twisting the cable or having it make
sharp, right angle turns.
• Never unplug a cable by pulling on the wire
itself. Always unplug by firmly grasping the
body of the plug and pulling directly outward.
If you experience difficulty in removing the
plug, sometimes a slight rotating motion while
unplugging will solve the problem.
• Keep the cable contacts clean at all time.
Oxidation may lead to intermittent contacts,
degraded sound quality, or even distortion. DO
NOT USE AN ABRASIVE TO CLEAN A DIRTY
PLUG. This may remove some of the plug’s
conductive plating. Instead, spray contact
cleaner on a clean, lint-free cloth and vigorously
rub the plug until the oxidation is removed.
• Although Alesis does not endorse any specific
product, chemicals such as Tweek and
Cramolin, when applied to electrical connectors,
are claimed to improve the electrical contact
between connectors.
• NEVER PLUG OR UNPLUG INPUT CABLES
UNLESS THE RA150/300/500 IS TURNED
OFF, UNPLUGGED FROM THE AC LINE, OR
HAS THE CHANNEL 1 AND CHANNEL 2
LEVEL CONTROLS TURNED TO MINIMUM
LEVEL. Failure to observe these precautions
may result in damage to your speakers if the
cable being plugged into the RA150/300/500 is
carrying a signal, and the level is turned up.
CABLE WIRING TIPS
If you decide to wire your own cables, Alesis
recommends that you use three-conductor shielded
cable (even in an installation that uses unbalanced
wiring) with either a braided or foil-type shield.
Connect one conductor to the phone jack tip
connection to carry the hot signal, and the shield
connection to the sleeve. The other conductor
should also connect to the shield since it is not good
practice to depend on the shield wire itself to
complete the signal connection. This is because the
shield wires are more subject to breakage, especially
in portable installations, than the more protected
internal insulated wires. By using a second “safety”
conductor for ground, the worst that could happen
with a broken shield would be a rise in noise or
hum due to the lack of shielding. If the ground
connection were completely lost, there would be
either extremely loud hum or major loss of audio.