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The Nº320S Preamplifier is a direct descendant of
the critically acclaimed Nº32 Reference
Preamplifier. The Nº320S features audio circuits,
controls, architecture, and phono input option
based on the Nº32. In fact, some audio circuits,
such as the proprietary discrete volume attenua-
tors, are identical to those found in the Nº32.
The single-chassis design of the Nº320S achieves
similar separation of audio circuit, control, and
power supply sections as the dual-chassis Nº32.
Inside the Nº320S, these sections are separated
by physical layout as well as a steel shield box
that protects against electrostatic and magnetic
interference. Filtered AC power is routed outside
audio circuit sections, providing audio circuits
with the quiet, shielded environment essential for
superior sound.
Many high-performance audio components rely
on clean, noise-free AC power to deliver
maximum performance. Unfortunately, most AC
power does not meet these standards. Common
household appliances such as refrigerators, televi-
sions, and computers often contaminate AC
power lines with line noise, spikes, and other
irregularities that make it difficult for high-
performance audio circuits to reach their full
potential.
To compensate for this, the Nº320S offers a series
of highly effective noise suppression and isolation
technologies. AC power is filtered for noise as
soon as it enters the chassis. The audio section
and control section have completely independent
power supplies, each with their own low-noise
toroid transformers. The audio power transformer
features a Faraday shield between the AC lineand the low voltage secondaries for improved
isolation. The Nº320S employs two stages of
active voltage regulation for the audio sections. A
high-power stage absorbs line voltage and temper-
ature variations, while a second
high-performance stage provides local, high-
speed, low-noise power for the audio section.
Featuring an advanced dual-mono design, the
Nº320S is endowed with remarkable channel
separation and exceptional sonic imaging. Both
audio channels use independent power supplies,
communication circuits, and audio circuits. In
addition, each channels audio circuits are located
in a separate area of the chassis. This innovative
design isolates each channel from the other,
allowing the Nº320S to produce vividly rich,
three-dimensional sonic images with stunning
precision.
For even greater channel isolation, the Nº320S
deactivates unused inputs to prevent interference
from associated components. When an input is
deactivated, the Nº320S disconnects the input
signal and ground connection, eliminating ground
loop noise between the Nº320S and the associat-
ed component. As a result, input signals pass
through the Nº320S with exceptional freedom
from interference due to other components.
Two Mark Levinson-designed discrete volume
attenuator modules control master volume level
with unparalleled accuracy and sonic neutrality.
Constructed with Arlon 25N circuit boards with
local power supply regulation and bypass capaci-
tors, these modules generate optimal power and
isolation for even the most sensitive adjustments.
Precision surface-mounted resistors accommodate
adjustments in 1.0dB increments up to 23.0dB
and 0.1dB increments above 23.0dB.
Unlike other stereo preamplifiers, the Nº320S is
designed to integrate with multi-channel
surround sound processors -“ minus the drawback
N
o
320S
PREAMPLIFIER
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of competing master volume level controls. A
unique surround sound processor mode allows
the Nº320S to set its master volume level control
to unity gain, passing complete control to the
surround sound processor. With no interference
from the Nº320S, the surround sound processor
can maintain the relative volume level of all chan-
nels without distorting its carefully calibrated
input and output levels.
A modest connector complement includes three
balanced (XLR) and four single-ended (RCA)
input connectors. Single-ended input signals are
converted to balanced signals upon entering the
chassis, and processed as balanced signals there-
after. During this conversion process,
meticulously balanced circuits preserve all input
signal information, passing it to the power ampli-
fier without the limitations of more asymmetrical
single-ended designs.
The rear panel also includes separate main and
record output connectors, as well as two Link
communication ports that make it possible for the
Nº320S to be included in Mark Levinson Link
systems.
A large front panel select knob provides quick
selection of the desired input. When an input is
selected, just press and hold the front panel or
remote control setup button to open the corre-sponding Set Inputs menu, which can be used to
select a custom name, optimize gain levels, set a
master volume level offset, or assign record
output connectors to individual inputs.
Following in the footsteps of the Nº32, the
Nº320S exceeds all reasonable expectations for a
stereo preamplifier. Its flexible design, including
seven configurable inputs, separate main and
record outputs, and full surround sound proces-
sor integration, allow it to accommodate a wide
range of demands. Even more, several advanced
technologies protect audio circuits for a superior
sound sure to complement even the most sophis-
ticated home entertainment systems.
Highlights
-7 configurable inputs
-Separate main and record outputs
-3 balanced (XLR) inputs
-4 single-ended (RCA) inputs
-Complete surround sound processor integration
-Advanced dual-mono design
-Maximum channel isolation
-Independent power supplies for audio circuit
and control sections, each with their own low-
noise toroidal transformer
-Effective noise suppression and isolation tech-
nologies
-AC power filtering
-Two active voltage regulation stages
-Faraday shield to separate AC power from low-
voltage secondaries
-Independent audio circuits, communication
circuits, and power supplies for each channel
-Two proprietary discrete volume attenuator
modules
-Deactivation of unused inputs to eliminate
ground loop noise
-Balanced conversion for single-ended input
signals
-Intuitive Set Inputs menu
-Large front panel display
-Two Mark Levinson Link communication ports
-RS-232 communication port
-Trigger output connector
-IR input connector
-Phono input option
320S shown with the steel
shield box removed.