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N
0
52 RefeReNce PReamPlifieR
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Owner’s Manual
sPecial Design featuRes
Thank you for purchasing the N
0
52 Reference Preamplifier,
featuring an innovative dual-chassis design that allows the
audio circuits to deliver unrivaled musical reproduction. The
N
0
52 Preamplifier chassis isolates the audio circuits so that
only audio signals and extremely pure DC power are present.
The power supply and control circuits are combined in the other
chassis, protecting the sensitive audio signals.
Like most high-performance audio components, the N
0
52 relies
on clean, noise-free power to deliver maximum performance.
Unfortunately, most AC power does not meet these standards.
Common household appliances such as refrigerators, TVs and
computers often contaminate AC power lines with line noise,
spikes and other irregularities that make it difficult for audio
circuits to perform up to their full potential.
To protect audio circuits from contamination, the N
0
52
generates its own “secondary” AC power. An independent
power supply is dedicated to each audio channel, generating AC
power for a special power amplifier optimized to reproduce just
one frequency: 200Hz. This 200Hz frequency is rectified, filtered
and regulated again to create extraordinarily clean DC power.
A third cable supplies control signals between the Controller
and Preamplifier chassis’, preventing potentially noisy control
signals from coupling into the power supplies.
An advanced dual-mono design allows the N
0
52 to achieve
exceptional channel separation. Both audio channels use
independent power supplies, communication circuits, and audio
circuits. The Preamplifier chassis provides complete isolation
between the left and right channels, which are physically and
electrically separated by a thick aluminum wall. This innovative
approach isolates each channel, allowing the N
0
52 to produce
vividly detailed, three-dimensional sonic images.
For even greater isolation, the N
0
52 effectively deactivates
unused inputs to prevent interference from other components.
Discrete “T-switch” input switching, special shielding and
optimal circuit board placement allow the N
0
52 to “unplug”
inputs not in use – achieving more than 120dB separation
between even adjacent input connectors. As a result, input
signals pass through the N
0
52 with remarkable freedom from
interference.
The N
0
52 offers seven configurable inputs, each of which is
assigned to one of its three balanced (XLR) or four unbalanced
(RCA) stereo connectors. Unbalanced input signals are converted
to balanced signals upon entering the Preamplifier chassis, and
processed as balanced signals thereafter. During this rigorous
conversion process, meticulously balanced circuits preserve
all input signal information, passing it to the associated power
amplifier without the limitations of asymmetrical designs.
In addition to the above-mentioned inputs, the N
0
52 also offers
a dedicated phono input featuring a proprietary Mark Levinson-
designed RCA connector that provides the same common mode
noise rejection benefits as a balanced XLR connector. The input
gain stage produces a symmetrical pair of opposite polarity
signals, based solely on voltage differences present at the input.
Each balanced signal follows the same signal path, including
identical RIAA equalization. Gain is distributed over two stages,
allowing ample bandwidth and open-loop gain for superior
performance – even at the 60dB input gain required for moving-
coil phono cartridges. Originally introduced with the N
0
38, the
instrumentation amplifier stage resolves tiny electrical signals
from potentially noisy environments. This method offers
high common mode noise rejection without the limitations of
transformer-based designs. And to prevent the introduction of
radiated noise, the phono section is double isolated from the
rest of the preamplifier.
A balanced pair of RIAA equalization circuits follows the input
gain stages. These circuits include a filter constructed with
0.1% non-inductive thin-film resistors and 5% stacked-film
capacitors for uncompromised RIAA curve accuracy.
The Setup menu for the Phono input provides multiple loading
and input gain options that allow compatibility with most phono
cartridges, including moving-coil, moving-magnet, high-output
and low-output designs. The menu also provides a switchable
20Hz high-pass filter and allows compensation for left/right
phono playback device imbalances of up to 3.0dB in 0.1dB
increments.
A Mark Levinson-designed discrete volume attenuator controls
the master volume level with unprecedented accuracy and sonic
neutrality. Constructed from Nelco
®
4000-13SI circuit boards
with local power supply regulation and bypass capacitors,
this volume attenuator generates optimal power and isolation
for even the most sensitive adjustments. Sixty-eight surface-
mounted, precision resistors per channel provide more than
65,000 possible settings between 0dB (maximum attenuation)
and 80dB, accommodating adjustments in 1.0dB increments up
to 23.0dB and in 0.1dB increments above 23.0dB.
The N
0
52 is designed to integrate with multichannel surround-
sound processors without the complications associated with
competing stereo and multichannel volume controls. A unique
surround-sound processor (SSP) mode deactivates N
0
52 volume
controls and sends line-level input signals to the associated
processor. With no interference from the N
0
52, the processor
controls the relative volume level of all channels, maintaining
its carefully calibrated output levels.
sPecial Design featuRes
