preamplifier
A new approach to preamplification
The darTZeel NHB-18 NS is the logical partner to the
now acclaimed NHB-108 model one power amplifier.
In keeping with the very same philosophy, darTZeel
uses dedicated circuits reduced to their most basic
form. Here again, there is no application of any overall
negative feedback. The delicate, small audio signal
amplified by the NHB-18 NS only passes through 8 silicon junctions from input to output, including the 13dB
Leading-edge audio electronics
At this level of performance, every detail is of prime
importance.
The delicate, small signal delivered by the sources is
amplified by discrete devices, or by means of matched
transistors embedded in dedicated integrated
circuits.
No operational
amplifier is used
in the entire signal path. As for
the NHB-108, all
components used
in the NHB-18 NS
preamplifier, with no exception whatsoever, are based
on the finest products being produced by leading-edge
industries at the present moment.
The first aim of the NHB-18 NS is to provide sound reproduction quality Never Heard Before.
Instead of offering a preamplifier based on the same
approach as that of our competitors, we at darTZeel
chose to think differently, offering for the first time in
the world what previously seemed impossible:
• No contact or switches or relay of any kind for the
selection of the sources. This revolutionary feature
brings a new level of transparency. Instead of routing
the signal through a selector box, each input has its
own dedicated gain stage, which is enabled or disabled
according to the user’s choice. The signal is then directly routed to the volume control module.
NHB - 18 NS preamplifier zero contact signal path
NHB-18 NS
full discrete gain stage. For the phono stage, we o nly
add 3 junctions, for a maximum additional boost of 60
dB (72 dB in total).
The advantages of these new circuits, whose designs
are patent pending, are in the same league as the
NHB-108 power amplifier: an extreme, pure sound
quality never achieved before
• A whole new volume control module, which com-
pletely avoids the use of any potentiometer, stepped
attenuator or analog switch array in the signal path.
The sound signal is attenuated in a fully passive way,
within a continuous range of close to 90 dB, in full
nal. As mentioned above, this new design is patent
pending. As soon as the patents are confirmed,
darTZeel will be pleased to describe in detail how such
signal treatment is possible.
The NHB-18 NS is not only new in these aspects. We
have also included all the features already implemented in our now famous NHB-108 model one, as follows:
• Only small local negative feedback at the inputs.
• One small, symmetrical, local negative feedback in
the voltage gain stages.
• Open loop, free of all negative feedbac k for the out-
put stages.
.
analog mode,
without the use
of any VCA or
other active component.
Both of these
breakthroughs
constitute a big
step in the right
direction: no
harm to the sig-
In addition, the NHB-18 NS features full modular possibilities, including future use of multi-amping by using
darT to Zeel 50-ohm links. Some key features are (per
channel):
• 5 inputs, whether phono, RCA/BNC or balanced XLR.
As standard, the NHB-18 NS is delivered with 2 full
floating XLR inputs and 3 RCA/BNC 50 ohm Zeel inputs.
• 2 XLR full floating outputs.
Power supply
The darTZeel NHB-18 NS is an authentic dual mono preamplifier, from input to output, with separate grounds
for left and right channels.
Each channel is battery powered by its own battery
bank, offering 10 to 12 hours of listening pleasure before a charge is
needed.
A very sophisticated,
regulated and dedicated supply for
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every input and
PUSH
output is provided,
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• 3 BNC 50 ohm darT outputs, ready for tri-amping,
with optional built-in passive filters.
• 1 RCA output.
• 1 RCA record output (fixed level).
• 1 dedicated headphones output, with its own amplifi-
cation circuit.
Other configurations are optional upon request.
ensuring the lowest power supply impedance possible.
A smart automatic function is provided as standard,
allowing full battery operation when listening, and
charging mode being activated when the preamp is
switched off. Hum
is gone forever,
and there is no
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need to worry about
knowing if batteries need to be
charged or not.
Technical Specifications
Output voltage : 4 volts RMS for RCA and XLR outputs, 2 volts RMS@ 50 ohms (darT outputs)
Line gain : 13 dB
Input impedance : Line RCA > 100 kohms, from 5 Hz to 200 kHz
Line XLR > 30 kohms, from 20Hz to 40 kHz
BNC 50 ± 1 ohms
Output impedance : 50 ohms
Bandwidth : 5 Hz to 500 kHz, +0, -1 dB
Rise time < 500 ns
Slew rate: > 24 V/µs, peak-peak
THD: < 1% from 10 Hz to 100 kHz
Temporal distortion : None
S/N: > 100 dB (A) @ 2 volts RMS output for line inputs. Phono figures not available yet.
Pwr consumption : 50 watts for 5 hours (batteries fully empty) when charging, then 5 watts.
Dimensions : 440 (W) x 150 (H) x 335 (D) millimeters. Figures not confirmed yet.
Weight : Not known yet.
Audio SA. All rights reserved.
2, ch. Louis-Hubert, Geneva, Switzerland.
Email: info@dartzeel.com
Web: www.dartzeel.com