NAD T 765 - Manual (Page 7)

DEALING WITH HUM AND NOISE
Hum and noise may sometimes prove a challenge in complex, multi-channel audio systems. Note
these considerations to help prevent hum and noise problems:
• Power all your system's audio component from AC outlets originating from the same circuit of your
house wiring. As far as possible, power all audio components from the same outlet, or adjacent
outlets on the same circuit. It may be useful to power video displays (and computers!) from outlets
on another circuit, especially if that circuit is supplied from the other "leg" of the house wiring.
• Do not bundle analog audio cables with AC power cables, or with coaxial digital-audio cables. It is
best if they cross at right angles if they must be in close proximity.
• Employ high-quality, well-shielded audio cable throughout, and ensure that all connections are
secure.
• A pencil-eraser can be used to burnish copper- and gold-plated contacts to ensure good, low-
resistance contact; specialized contact-cleaners can also be useful. Avoid unnecessary unplugging
and re-plugging since the gold (or copper) contact plating of typical cable connectors, even very
high-quality ones, is very thin and easily worn.
Track down hum/noise problems one component at a time, working backwards from the A/V Receiver.
That is
a. Connect the speakers to the A/V Receiver only, and check for hum.
b. Then connect one component only (a CD player, for example) alone, with no other
components connected and check for hum.
c. Connect additional components, one at a time, to the A/V Receiver and check for hum.
At each stage, if hum/noise appears, examine the audio cabling and AC-power routing of the new
component. In some cases, moving the new component's AC cord to a different outlet, or installing a
ground-lift (3-to-2-prong adapter) on its power cord, will eliminate the hum.
INTRODUCTION
GETTING STARTED
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