E6
NAC 252
7 NAC 252 Introduction and Installation
The NAC 252 preamplifier does not incorporate an internal power supply and can be used
only in conjunction with a SuperCap power supply. Diagram 8.2 illustrates connection of the
NAC 252 to a SuperCap power supply.
The preamplifier and power supply should be installed on a dedicated equipment stand
intended for the purpose. Do not stand either directly on top of another item of equipment.
Care should be taken to ensure that the preamplifier is level.
The preamplifier and power supply should be installed in their final locations before
connecting cables or switching on. Ensure that power amplifiers are switched off and the
preamplifier volume is turned down before the power supply is switched on. The power
button is located on the power supply front panel.
The power supply is heavy and care should be taken when lifting or moving it. Make sure that
the surface on which it is to be placed can support its weight.
The following paragraphs describe installation features and functions specific to the NAC 252.
Operational features common to all preamplifiers are described in Section 14.
7.1 Source Inputs and Record Outputs
The input selection buttons arranged along the upper bank
select the source signal to be routed to the power amplifier
and the loudspeakers. Below them, in the lower bank, are a
corresponding array of buttons which select the signal to be
routed to the preamplifier’s record outputs.
These separate source and record sections enable one source
(a CD player, for example) to be listened to whilst the output
from another (say, the tuner) is simultaneously selected for
recording.
Note:
It is possible to lock the record controls and prevent
accidental de-selection during recording. Record-lock is
switched on or off by pressing the source mon button four times
within six seconds.
7.2 Input Socket Assignment
The NAC 252 has six DIN input sockets and two alternative
pairs of RCA Phono sockets. The RCA Phono sockets can be
assigned individually to the
cd
and
aux 2
input buttons in place
of the DIN sockets.
Input assignment setup is accessed through the NAC 252
program mode. To switch into (or exit from) program mode
press and hold the
prog key
on the remote handset (in
preamplifier mode). Program mode is indicated by a flashing
indicator on the front panel volume control and the record
selection indicators extinguishing.
Note:
If no function is operated within five minutes of entering
program mode the NAC 252 will return to normal mode
automatically.
Once in program mode press and hold the remote handset
1
key to select or de-select the RCA Phono socket input for
cd
, and the remote handset
6
key to select or de-select the
RCA Phono socket input for
aux 2
. The corresponding front
panel input buttons can similarly be used to select or de-select
the RCA Phono socket inputs. The appropriate input button
indicator will flash three times on selection of the RCA Phono
option and once on selection of the DIN option.
To exit from program mode press and hold the
prog
key on the
handset until the record select indicators are restored and the
volume indicator stops flashing.
7.3 Record Mute
At times when the NAC 252 record outputs are not required
it is good practice to mute them in order to minimise power
consumption and maximise sound quality.
To engage the NAC 252 record mute simply press the record
(lower) bank front panel
mute
button.
7.4 NAC 252 Signal Outputs
To ensure correct continuity of system earth connections
the NAC 252 signal output is routed via the SuperCap power
supply. The SuperCap is fitted with multiple DIN signal output
sockets that enable the downstream connection of a stereo
power amplifier, a dual mono power amplifier or two separate
mono power amplifiers.
7.5 Auxiliary Power Output
The NAC 252 Aux 2 input (In 6) is provided with primary and
alternative DIN sockets. The lower, alternative, socket, fitted
at manufacture with a removable cover, is intended for use
with a Naim Audio StageLine or SuperLine phono stage and
incorporates an appropriate DC power supply. The primary and
alternative sockets must not be used simultaneously.
Operational features
common to all
preamplifiers are
described in Section 14