NAD S200 Manuel D'installation page 5

CAUTION: Safety organisations recommend that the speaker
terminals of a very powerful amplifier should be covered. Potentially
dangerous voltages are present on these terminals when the
amplifier is producing maximum power. For your protection and in
order to comply with these regulations, we have chosen speaker
terminals of the very highest quality for the NAD S200. These
terminals are covered by plastic bushings which prevent the touching
of metal parts.
PHASING
Stereo speakers must operate "in phase" with each other to produce
a focused stereo image and to reinforce rather than cancel each
other's output at low frequencies. An in-phase connection is assured
if the red (positive) terminal on the amplifier is connected to the red
(positive) terminal on the loudspeaker in each channel.
If your speakers are easily moved, their phasing can easily be checked.
Make the connections to both speakers, place the speakers face-to-
face only a few inches apart, play some music, and listen. Then swap
the connection of the two wires at the back of ONE of the speakers,
and listen again. The connection which produces the fullest, boomiest
bass output is the correct one. Connect the wires securely to the
speaker terminals, being careful not to leave any loose strands of wire
that might touch the wrong terminal and create a partial short-circuit
then move the speakers to their intended locations.
If the speakers cannot easily be set face-to-face, then phasing must
rely on the "polarity" of the connecting wires. The speaker terminals
on the amplifier are identified as red (+) and black (-) in each
channel. The terminals at the rear of the speakers are also marked
for polarity, either via red and black connectors or by labels: "+",
"1", or "8 ohms" for positive, "-", "0", or "G" for negative. The
red (+) terminal on the amplifier should be connected to the red
(positive) terminal of the speaker in each channel.
To facilitate this, the two conductors comprising the speaker wire in
each channel are different, either in the colour of the wire itself
(copper vs. silver) or in the presence of a small ridge or rib pattern on
the insulation of one conductor. Use this pattern to establish
consistent wiring to both speakers of a stereo pair. Thus if you
connect the copper coloured wire (or ribbed insulation) to the (+)
amplifier terminal in the Left channel, do the same in the Right
channel. At the other end of the wire, if you connect the copper
coloured wire (or the ribbed insulation) to the red or positive terminal
on the left channel speaker, do the same at the right channel speaker.
3. LEFT CHANNEL INPUTS
(BALANCED/UNBALANCED)
Before making or changing input connections to the amplifier, make
certain that the Power is Off.
The S200 amplifier is equipped with two input connectors for each
channel. The RCA phono jack is a conventional "unbalanced" input.
The three-hole XLR socket is a professional "balanced" input. You
may use either type of input, but not both.
If your preamplifier has only conventional outputs with RCA phono
jacks, connect an audio connecting cable from the left channel
output of the preamplifier to the left channel UNBALANCED input of
the S200. Set the BALANCE switch to UNBAL.
If your preamplifier has balanced XLR outputs, connect a three-
conductor cable from your left channel preamplifier output to the
left-channel XLR input on the S200, and set the BALANCE switch to
BAL. If your audio dealer does not have the appropriate cables,
purchase balanced "microphone" cables from a shop that sells
professional recording equipment. The end of the cable that has a
"male" XLR plug (with three metal pins) should be connected to the
S200 amplifier. The end of the cable that has a "female" XLR socket
(with three holes) should be connected to your preamplifier.
An XLR plug is "keyed" so that it fits into the socket only one way. If
there is a set-screw in the barrel of the plug, align it with the top of
the connector. Push the plug fully into the XLR socket until it latches
in place.
The three pins of an XLR type ("Cannon") connector are numbered.
Pin 2 is the signal "hot" connection in the S200, Pin 2 is connected
directly to the center pin of the unbalanced RCA phono jack. Pin 3 is
the signal return (signal ground) connection. Pin 1 is the chassis earth
(ground), to which the shield of a balanced-wire cable is connected.
UNPLUGGING
The XLR socket has a latching feature that prevents the connector
from being pulled out by accident. Before disconnecting an input
cable, turn off the Power. Use one hand to press the latching tab
above the XLR socket while using the other hand to pull the XLR
plug out.
4. RIGHT CHANNEL INPUTS
(BALANCED/UNBALANCED)
Make connections to the right channel input in the same way that
you did for the left channel.
5. INPUT SELECT (BALANCED/UNBALANCED)
Set this switch to match your selection of input connector. Set to
UNBAL if you have connected a cable from your preamplifier to the
RCA phono input jacks. Set the switch to BAL if you are making
connections to the balanced XLR inputs.
Normally the choice of input connector is determined by the output
connectors on your preamplifier. If your preamplifier has balanced
outputs, use three-conductor cables equipped with XLR connectors.
If your preamplifier has only "unbalanced" connections with RCA
phono jacks, use the corresponding inputs on the S200.
GB
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