NAD 218 THX, Owner'S Manual

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A NOTE ON INSTALLATION
This unit may be installed on any level surface that
is strong enough to support its weight. Since its
power transformer generates a significant magnetic
hum field, a turntable (especially one with a moving-
coil pickup cartridge) should not be located adjacent
to the amplifier nor directly above it.
The heat-sink fins make it awkward to lift the 218
THX by grasping the left and right sides. You may
find it more practical to place your hands under the
front and rear panels. Much of the amplifier’s weight
is near the front panel.
CAUTION: The amplifier’s weight must always rest
on its bottom feet. Never put the amp down on its
rear panel, with its front panel facing up. Doing so
risks damage to the input/output connectors.
The amplifier generates a moderate amount of
heat, requiring internal ventilation. Do not permit the
air outlet grille on the top cover to be obstructed by
papers or articles of clothing. If you want to locate
the amplifier on a carpeted floor, place a board under
the amp in order to prevent it from sinking into the
carpet, blocking the air inlets on its bottom.
CAUTION: To prevent a fire or shock hazard, do
not permit liquid or moisture to enter the amplifier. If
liquid is accidentally spilled on it, immediately shut off
the power and unplug the AC power cord. Allow time
for complete evaporation to occur before operating
the amplifier again. (If the liquid is anything but water
and/or alcohol, the amplifier should be examined by a
service technician before power is applied to it.)
Do not open the amplifier, or attempt to modify or
repair it yourself. Refer all servicing to a qualified
technician.
REAR PANEL CONNECTIONS
1. AC POWER CORD
Plug the AC power cord into a live wall socket. If
you must use an extension cord, select a heavy-duty
cord of the type used for large electrical appliances.
Do not connect the amplifier’s power cord to the
accessory AC outlets on a preamplifier. Such conve-
nience outlets are not designed to supply the high
power levels, up to 800 watts, that the 218 THX
requires. If you wish to switch your entire audio sys-
tem on and off at once, plug both the 218 THX and
your preamp into a “power strip” containing several
grounded AC outlets and a high-current on/off switch.
Voltage conversion. A notice printed on the rear
indicates the AC power-line voltage that the amplifier
requires. However every Model 218 THX amplifier
has a “universal” power supply that can be modified
easily for operation in other countries. If you wish to
transport your 218 THX to a nation that employs a dif-
ferent power-line voltage, an authorised NAD dealer
or service agency can convert it for such use.
2. SPEAKERS
This amplifier is equipped with special high-current
binding-post speaker terminals to handle the highest
peak power levels that may occur in the “bridged”
mode or with low-impedance speakers. At moments
when the amplifier is producing maximum power,
voltages of nearly 100V may be present on the
speaker terminals, so the terminals are protected by
hinged plastic safety covers.
To connect loudspeaker cables, first switch off the
amplifier’s power. If you are connecting a pair of
speakers for normal stereo operation, be sure that
the Bridging switch is set to OFF (STEREO). Raise
the plastic cover to gain access to the
SPEAKERSterminals.
For best stereo imaging, the left and right speakers
should be located at equal distances from your chair.
To minimize the effect of speaker cables on the
sound, locate the amplifier near the speakers and use
short cables to connect the speakers. If your pream-
plifier is located at the opposite end of the room near
your chair, you will need a long cable to connect it to
the power amplifier. All NAD preamplifiers have the
low output impedance required to drive long connect-
ing cables.
Connect the wires from your left-channel speaker
to the (L+) and (L-) terminals in the SPEAKERS
group, and connect the wires from the right-channel
speaker to the (R+) and (R-) terminals. In each chan-
nel the red terminal is the positive (+) output, and the
black terminal is the negative (-) or “ground” terminal.
Use heavy-duty (16-gauge or thicker) stranded
wire, especially with 4-ohm loudspeakers. Bare wires
can be connected directly to the binding-post termi-
nals. For a longer-lasting and more corrosion-resis-
tant connection you may purchase speaker cables
with nickel or gold-plated connectors (pin connectors,
spade lugsfor 230V versions, or banana plugs for
120V versions), or you can install such connectors on
the wires yourself. Connections to each binding post
may be made in several ways, as follows.
(1) Pin connectors. A pin connector is a slim metal
shaft that is crimped or soldered onto the end of a
wire. The threaded shaft of each binding post con-
tains an opening that accepts pin connectors up to
3mm in diameter. Unscrew the red or black plastic
bushing on each terminal to expose the hole in the
metal shaft. Insert the pin connector through the
hole, and turn the bushing clockwise until it is tight.
(2) Spade lugs. Unscrew the colored bushing,
insert the U-shaped spade lug behind the bushing,
and tighten the bushing down on it.
(3) Bare wires [See Figure 1]. Separate the two
conductors of the cord, and strip off a half-inch (1 cm)
of insulation from each. In each conductor, twist
together the exposed wire strands. Unscrew the red
or black bushing, insert the bare wire through the
hole in the metal shaft, and tighten the plastic bush-
ing until it grasps the wire securely. Check to be sure
that no loose strand of wire is touching the chassis or
an adjacent terminal. (Loose strands can be prevent-
ed by “tinning” the bare wire with melted solder
before you connect it to the amplifier.)
CAUTION: Safety organizations recommend that
the speaker terminals of a very powerful amplifier
should be covered. Potentially dangerous voltages
NAD
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NAD 218 THX POWER AMPLIFIER