darTZeel NHB-458 User manual

NHB-458 Monoblock Amplifier
User Manual

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Table of contents
1. Preliminary notes _______________________________________________________ 5
2. Introduction ___________________________________________________________ 5
3. Brief description________________________________________________________ 5
4. Warranty______________________________________________________________ 6
5. Installation ____________________________________________________________ 6
5.1. Unpacking_______________________________________________________________________6
5.2. Location ________________________________________________________________________7
5.3. Connections______________________________________________________________________7
6. The NHB-458 in detail___________________________________________________ 8
6.1. Front panel ______________________________________________________________________8
6.2. Rear panel _______________________________________________________________________8
6.2.1 Fuse and voltage settings__________________________________________________________9
6.3. Remote control ___________________________________________________________________9
7. Activation key procedure ________________________________________________ 10
8. User parameters _______________________________________________________ 10
8.1. Main features____________________________________________________________________10
9. How to set everything___________________________________________________ 10
9.1. Power-on sequence _______________________________________________________________11
10. Full configuration and settings ___________________________________________ 11
11. Some advice and tips ___________________________________________________ 18
11.1. Cleaning and upkeep____________________________________________________________18
11.2. What not to do_________________________________________________________________18
12. Assistance ____________________________________________________________ 18
13. Technical data ________________________________________________________ 19

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darTZeel NHB-458 monoblock amplifiers
User Manual
1. Preliminary notes
The NHB-458 cannot be user switched from a
different voltage setting than the one set at factory.
This is an operation that only your authorized dealer
can perform. Any attempt in changing voltage
setting will void the warranty.
Be sure that your AC wall voltage corresponds with
NHB-458s’ factory settings.
Your NHB-458 pair comes with a USB activation
key to provide the required identification data to
your NHB-458‘s internal CPU.
Usually, both monoblocks come already activated to
your name. If it would not be the case, you could use
the provided USB keys in order to program en
eventually unlock them. In such a case please
contact your authorized dealer.
Please refer to chapter 7, “Activation key
procedure” (page 9), for how to obtain your USB
activation-key data file.
Please read this user manual in its entirety.
As it is the darTZeel rule, we did our best to avoid
making you fall asleep. We hope to be successful in
that regard…
While already being pretty impressive out of the
box, your NHB-458 will require about 170 hours of
playing time before it approaches its full potential.
2. Introduction
Congratulations on your purchase of a darTZeel
NHB-458 monoblock pair.
The darTZeel NHB-458 is the most advanced
analogue monoblock amplifier yet designed.
Grace, Delicacy and Power are the words which
describe these musical machines the best.
The NHB-458 is the culmination, in terms of power
amplification, of more than 30 years of true love and
dedication to music reproduction.
Not only NHB-458s do joyfully distillate the
slightest “pianissimi” with unbelievable realism,
they also transport you into the heart of the musical
event, effortlessly reproducing the loudest
“fortissimo” without any kind of limitation but your
hearing threshold of pain.
Designed for uncompromising musical and
emotional performance, the NHB-458 will
nevertheless give its best when paired with the
darTZeel NHB-18NS, the only preamplifier in the
world using true 50-ohm matched impedance links
as well as the unique and ultimate analog optical
“zero contact” volume control signal path.
With its fluorescent display, you will have an easy
and comprehensive access to the various operational
menus.
With its very conservative ratings, the NHB-458 is
comparable to a never ending energy reservoir.
Bench tested at half a kilowatt under 8 ohms in
continuous mode, it can deliver twice this power
when playing music, and even much more than this
when using 4-ohm speakers.
So, please be careful when you will start to tame
these beasts. A single vinyl crackle can peaks at
more than 300-400 watts because of the
unprecedented speed and dynamics available.
Otorhinolaryngology medical consultation is not
included in the purchase price, so allow for your
hearing some time to adapt.
3. Brief description
Your NHB-458s are the result of all the research
and development we have brought to the audio
industry over the past decades.
Our passion and love for music and its reproduction
have been embodied in the NHB-458s.
The challenging goals we set for ourselves were to
design and then build a power amplifier with no
sound either built quality compromises.
You are among the very few owning a very unique
design, and we at darTZeel are very proud to share
this experience with you.
The entirely newly-developed audio circuits will
drive any real-world load in a breeze, transforming
your loudspeakers into a new window open to the
music, anyhow they previously sounded so far.
With the NHB-458s’ more than 450 watts RMS into
8 ohms, and 750 watts RMS into 4 ohms, even low-

darTZeel NHB-458 User Manual, version 1.0 Page 6 of 19
sensitivity speakers will put out plenty of volume
during your most demanding – dynamically
speaking – listening sessions. When it comes to
music reproduction, power is not needed in a
sustained way; then enters the phenomenal dynamic
power reserve.
Thanks to the huge 750 joules of energy available
from the enormous capacitor reservoir, short but
repetitive peaks in excess of 1 kW – yes, more than
1,000 watts – are delivered in a very clean way, and
much faster than the time of an eye blink – here we
mean a standard, human eye…
From the technical point of view, there is no doubt
that the NHB-458 is a very special machine. Every
single part was carefully selected, from the first
resistor to the last power output transistor.
Adding to the beauty, in those “green” days, we are
proud to say the NHB-458 actually runs very cool,
saving on your electrical bill.
Needless to say those extraordinary performances
deserve an equivalent outstanding dressing. We use
our own aluminum alloy, made from custom made
extrusion forms, and then both finishing and
anodizing are performed by real artwork craftsmen.
When assembly time comes, our dedicated crew
lovely assembles every module day after day until
final completion; then our assembly chief engineer
carefully looks for irreproachable making before
bringing the NHB-458 onto the final 3-days bench
test.
This is why you waited so long in getting your
darTZeel NHB-458 monoblock power amplifiers.
Not that we like to make our esteemed customers
waiting for months but simply because love is also
lot of pain and efforts to cope with, needing time to
smooth everything down.
We are indeed very proud to say that our “Never
Heard Before” motto plenty takes place when one
talks about NHB-458monoblock power amplifiers.
As for the most important thing you can ask for, and
we obviously mean the music, you will simply find
them… Enthralling.
4. Warranty
Your NHB-458s are guaranteed for one full year (parts
and labor), against any breakdown or component
failure, as is the tradition in Switzerland for such
equipment.
As we view it, any electrical component with no
moving parts either will fail within days, or will last
virtually “forever.”
This is the reason all our machines are thoroughly
tested and broken in, before being lovingly packed
and sent on to you.
We are nonetheless aware that no component is
always flawless, and that a problem could arise after
the expiration of the warranty period.
In such a case, we will carefully examine all the
circumstances, with the aim of reducing the likely
repair costs to minimum levels.
You can always trust us for customer care, as you
already trusted us when purchasing your NHB-458s.
The warranty is valid in the original country of
purchase only.
The warranty is transferable to a single second-hand
user within the first year, but only in the original
country of purchase.
5. Installation
5.1. Unpacking
Your NHB-458s are delivered in an industrial
wooden crate. We understand this is the less
appealing part of the package; however it is the only
way we found to safely ship your 70 kg/each
emotional music reproducers.
Hopefully you will not have to bother unpacking the
darTZeel NHB-458 monoblock power amplifiers;
your authorized dealer will be very happy doing this
for you, taking a chance to admire them while
installing. A separate sheet is nevertheless provided
in order to explain how to proceed, in case you
would secretly want to install your machines by
yourself, during a dark, moonless night.
Please note that in case of future shipping, the
original crate must be used if you want to avoid any
possible damage.
Do no forget securing the power supply suspension
screws before shipping. Any shipping damage will
not be covered by the warranty if blocking screws
are not installed.
The wooden crates should contain:
•Two NHB-458 monoblocks amplifiers
•Two USB keys
•Eight golden plated screws
•Eight suspension securing screws
•Two AC power cables
•This user manual

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5.2. Location
There is one “Left” and one “Right” machine.
You can check this on rear panel, looking to the
RCA input: Left amplifier has its RCA outer ring
WHITE colored, and the Right amplifier has its
RCA outer ring RED colored.
Technically there is no difference between Left and
Right machines, but as you will connect them from a
stereo preamplifier which well has left and right
outputs, why not following the rule until the end, for
once…?
Left and Right identification is also displayed when
hitting the NAME key from the front panel. But as
this function is only available when you will power
your darTZeel NHB-458 monoblock amplifiers,
knowing this when locating them may help you.
Anyway if would have reversed them, you could
always claim to your friends that you chose L and R
as if you were on the stage.
Do NOT remove blocking suspension screws until
your machines will be definitively located. Moving
the NHB-458 will induce some power supply
oscillation; in case of mechanical shock, internal
anodized parts could be damaged.
Before making any connection, you should carefully
plan the location where you will install your gear.
Best place is just next to each loudspeaker. Doing so
will help to minimize speaker cable length; when
connecting your NHB-458s to a darTZeel NHB-18NS
preamplifier, we strongly recommend using our
darT to Zeel 50-ohm links which will not only
allow for ultimate performance level but also having
the preamplifier – and the rest of the installation –
located as far as needed, without any sound quality
loss.
We do NOT recommend installing the NHB-458s in
any furniture, unless you are healthy enough to play
with 70 kg at arm’s length.
Therefore, please be forewarned that the NHB-458
will stop playing if it becomes too hot. This is not a
situation which should ever occur under normal
listening operation, though.
Thermal protection will shut down your NHB-458s
at approximately 70°C (158°F). The power supply
will start up again when the operating temperature
will have dropped to 60°C (140°F).
It is also advisable, where possible, to leave enough
space around your NHB-458 to allow easy access
when making or changing connections.
5.3. Connections
Be sure that your AC wall voltage corresponds with
NHB-458s’ factory settings.
CAUTION!
Never, ever proceed to ANY connection /
disconnection before NHB-458s have been
powered off by at least 2 minutes!
Internal capacitor bank stores a lot of energy, and
any wrong manipulation and / or short could
possibly lead in a catastrophic failure by avalanche
breakdown.
Be sure that there is no short between speaker wires!
Warranty will be void if the above is not respected.
As internal supplies are ± 100 volts DC, we anyway
strongly recommend not playing with the rear panel
when the machine is ON. Those are lethal voltages,
so better not risking a shock – even if non-lethal in
most of cases – by playing with wires when the
NHB-458s are not switched OFF.
Apart from these – we hope so – scaring enough
indications, we want to reassure you in the way that
once your amplifiers will be properly connected, you
will have ones of the safest machines ever designed
in front of you.
Take your time when making all connections, check
them twice if needed. Here again, we think that
asking your authorized dealer for proceeding will be
a good idea.
Speaker binding posts are from CardasTM . We chose
this kind of binding posts because they allow for
very big spades, greatly help in avoiding – most of
cases – unwanted shorts, and they are the only ones
which can be well tightened up without being lose
over time. Thank you CardasTM!
When properly tightened, these connectors are
pretty reliable and well keep the pressure on spades.
Never use pliers to tighten, only do it by hand, the
provided external rubber is very helpful to just
tighten as firmly as needed without going mad.
In the case you would prefer banana plugs – which
also have our favor – ask your authorized dealer for
supplying a Spade-to-Banana adapter. We did not
chose 5-way/Banana binding posts for the NHB-458
because of quite high current and voltage involved.
As soon as the NHB-458 is plugged into the AC
wall outlet, its operation-status LED will turn red.
There is no master hardware (physical) on/off
switch. We hope you nevertheless will sleep well,
knowing that the NHB-458’s electrical-power
consumption in standby mode is less than 5 watts for
the pair.

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6. The NHB-458 in detail
6.1. Front panel
Hereunder functions are for direct keying.
Full key operational functions using the Menu Control
Panel are described in chapter 10.
1. Power Switch
When powered OFF (Stand By):
LStatus Led is RED.
When powered ON:
LStatus Led is AMBER.
2. Menu Key
This key gives access to all user parameters
described later in chapter 10
3. Upper Display Reading
When depressed twice and more, upper reading will
change from RMS, Peak, PeakHOLD, etc.
4. Lower Display Reading
When depressed twice and more, upper reading will
change from RMS, Peak, PeakHOLD, etc.
5. Name
When depressed twice, owner name with serial
number is displayed for about 10 seconds; another
hit will display the owner name continuously.
Depressing once again will display the darTZeel
logo continuously. A last pressing and the display
will resume to standard readings.
6. Display Illumination
When hit twice, AUTO DIM will be activated, meaning that after a predefined time, the display will shut off.
Depressing twice again and the AUTO DIM will be disabled.
The defined time after the display shuts off can be set via the Menu Control Panel; see chapter 10.
7. Menu Related Key
This key has no operational function when hit but only activates the direct key access display, as it is the case
for all other 3 to 6 keys.

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6.2. Rear panel
We think the rear panel labeling speaks for itself.
Nevertheless, we will try to keep you awake, by providing
some general information… .
Please note that only one input can be used at the
same time. All inputs are connected in parallel, so
connecting more than one input at a time will
dramatically reduce sound performance.
As you will see, 2 “Power on triggers” are provided.
They are intended for remotely power the amplifiers
ON when using a darTZeel NHB-18NS preamplifier.
These triggers are NOT standard 3.5mm audio jacks,
but signal oriented, professional Neutrik sockets.
Please ask your dealer if you want to use this feature.
As mentioned earlier, your darTZeel NHB-458
monoblocks amplifiers should already be programmed
for you, and activation would not be needed; Anyway,
you will note that we provide one USB port on the
lower left corner. This is the one into which you will
insert your USB key if further registering will be
required, or when a firmware update becomes available.
For whatever reason, if your machines would not have
been factory activated, please immediately ask your
dealer in order to obtain your registration key.
When you register your NHB-458, you will need to
insert your USB key into the rear panel’s USB port.
Please carefully read the chapter 7, “Activation key
procedure”, next page.
!!! YOUR MACHINE WILL OPERATE
FOR ONLY 15 MINUTES IF NOT PROPERLY
ACTIVATED !!!
6.2.1 Fuse and voltage settings
The voltage of your NHB-458s has been factory set.
Be sure that your AC wall voltage corresponds with
NHB-458s’ factory settings.
From 100 to 125 volts AC, the rear breaker is
indicated 16A.
From 200 to 250 volts AC, the rear breaker is
indicated 8A.
There is no any fuse to replace. The thermal breaker
is only intended to protect the machine and your
installation against catastrophic failure. No Fuse,
Better Sound!
Operating voltage cannot be user altered for
technical and obvious safety reasons – remember the
± 100 volts DC internal supplies and the huge
energy provided by the capacitor bank. No any
“switch” could handle those high current/voltage.
So, if you move to another country, you may have to
change the voltage setting. Please contact your dealer.
In this case, a new activation code will be required.
!!! Warning !!!
Any attempt to alter voltage setting will void the
warranty. Always ask your dealer for such an
eventual change.

darTZeel NHB-458 User Manual, version 1.0 Page 10 of 19
7. Activation key procedure
In case your darTZeel NHB-458 monoblock
amplifiers would not have been factory activated,
they will operate only for the 15 minutes following
each new powering on.
Please contact your dealer for remediate to this very
deploring situation in order to quickly activate your
machines.
Registration procedure:
We provide a USB activation key with each of your
NHB-458s. This keys are blank when you receive
them.
Ask your dealer to send you your activation-key data
files.
Please note that you will need both a “Left” and a
“Right” activation keys. You can know if which
machine is “Left” or “Right” by depressing the
“Name” key from the front panel, The serial number
ends either with an “L” or a “R”. Activation keys are
not interchangeable from Left to Right.
You will receive those by email in the form of a
zipped (data-compressed) folder containing a file
with a “dtz” name extension. If possible, use a PC
WindowsTM based computer when unzipping the
files; sometimes MACTM based computers could
corrupt the files and activation will not work.
How to proceed:
1. Unzip (decompress) the key-activation
software from the zip folder. Directly copy
the “dtz” file onto the USB key, using your
home computer. DO NOT ALTER THE
FILE NAME!
2. Insert the “loaded” USB key into the USB
port located in the rear panel of your
NHB-458.
3. From the front panel, sequentially press the
following: Menu ► Diag ► DTZ.
4. The file will be uploaded.
5. Remove the USB key.
At registration-inquiry time, please note that your
owner name cannot exceed 14 characters
maximum in length. So, please use “J.D. Smith”
instead of “Jonathan Donald Smith”… .
8. User parameters
The section starting at chapter 10 is the most
important part of this user manual.
Thanks to the intuitive menus, you will be able to
access all parameters directly from the front panel.
8.1. Main features
From the Menu Control Panel, you can, from other
things, adjust the following:
•Input ► RCA OR ZEEL OR XLR. Factory
setting is ZEEL. Remember you cannot
connect multiple inputs at the same time.
•Output gain ► 26dB or 32dB. Factory
setting is 32 dB.
•Power ON mode ► Music, Trigger, or
Manual (trigger OFF)
•Display intensity ► 25%, 50%, 75% or
100%. Factory setting is 25%. Please note
that using 100% all the time will reduce the
display span life.
9. How to set everything
The following pages show how to fully set up your
NHB-458s, by mean of schematic flow charts.
We reproduce most of display screens and explain
how to proceed, as if you were in front of your
machine.
Important note
In all Menu levels, depressing the “OK” key will
confirm the level you are in, and then you will be
able to alter settings. When not pressing “OK” first,
using arrows will make you navigate into another
Menu at same folder level.
Maybe trivial for your skill but nevertheless useful
to know… See chapter 10 for full explanations.

darTZeel NHB-458 User Manual, version 1.0 Page 11 of 19
9.1. Power on sequence
Here is what you will see on the display screen when powering the darTZeel NHB-458 on:
9.2. Direct Key Access
When hitting any key from 3 to 7, the display will show the hereunder direct access keys:
1. Power Switch
L. Status LED
2. Menu Key
3 4 5 6 7
By pressing DIM key the display will dim off after 2 to 15 seconds (see chapter 10.1.). Pressing again will cancel the
auto dimming function.
If you press D1, upper readings will change as follows at each pressing:
If you press D2, lower readings will change the same way D1did.
Explanation: WRMS means Root Mean Square, corresponding to the actual power dissipated in a pure resistor.
WPEAK is the peak power value; usually it corresponds to twice the sinus figure. However here we
prefer displaying the “Instantaneous RMS power”, which better corresponds to human hearing
perceived loudness.
WPEAK is the “Peak & Hold” value; here the reading keeps the highest value measured as long as
another mode is chosen. This is a practical way to measure the loudest part of a music song.
If you press NAME, readings will display the followings after each pressing:
If pressed once, lasts for about 10 seconds
If pressed twice, name display freezes Pressing name a third time
darTZeel NHB-458
This machine, number
TZ-UA1458.001L
Was built for
User Manual
0 Wrms
0 Wpeak
0 Wrms
0 Wpeak
D1 D2 NAME DIM
○○○○○
○○○
0 Wrms
0 Wpeak
D1 D2 NAME DIM
0 Wpeak
0 Wpeak
D1 D2 NAME DIM
0 Wpeak
0 Wpeak
D1 D2 NAME DIM
H
H
0 Wrms
0 Wpeak
D1 D2 NAME DIM
darTZeel
NHB-458
This machine, number
TZ-UA1458.001L
Was built for
NHB-458

darTZeel NHB-458 User Manual, version 1.0 Page 12 of 19
10. Full configuration and settings
Press the Menu key “2”, (chapter 6.1, page 8) on the front panel, and then play with the charts…
How to proceed:
•Press key 1-5 to select the desired parameter
•Once in the desired submenu, navigation works as is:
oUse arrows to navigate between the different available choices, then press OK to enter into the
desired parameter settings.
oThen navigate again into this new second level submenu using the arrows or "+" and "-" keys for
setting the desired parameter, then press OK to confirm the new setting.
•Pressing X key will go up to the upper sub menu level. Pressing X again will go to main Menu.
•Pressing RST will restore factory parameters in the corresponding sub menu level / settings.
10.1. Menu Display
►►
◄◄
You can choose the illumination
brightness. Press OK to confirm
brightness setting, and then use the "+"
and/or "-" keys to choose between 25,
50, 75 or 100%. Press OK again to
memorize the brightness level.
Press X to return into upper navigation
level.
Suggested setting: 25% in order to save
display life time. Press X once again to
return to main Menu.
Here you can choose display Auto-off
time, provided you previously selected
this function via the direct access key
(see cahpter 9.2).
Press OK to enter into the Auto-off
time sub menu, then press "+" and/or "-
" keys to select the desired time, and
then confirm with OK.
Press X to return into upper navigation
level. Press X once again to return to
main Menu.
If power indicators do not display "0
Watts" when music is not played, you
can recalibrate the power measurement
circuit by just pressing OK key.
From this particular sub-menu you do
not have to press X but left of right
arrow to navigate back. Pressing X will
return to main Menu.
MENU
1 Display 4 Trigger
2 Input 5 Diag
3 Output
1 2 3 4 5
DISPLAY
◄ Brightness ►
100 %
◄►RST OK X
DISPLAY
◄ Auto-off time ►
10 sec
◄►RST OK X
DISPLAY
◄ Calibration ►
of power meters
Press OK
◄►RST OK X

darTZeel NHB-458 User Manual, version 1.0 Page 13 of 19
10.2. Menu Input
Important note:
Only one input can connected at a time. Simultaneous inputs connected can lead to lower performance, and can
eventually damage the NHB-458.
▲▼
►►
◄◄
This BNC 50-ohm input is the preferred
darTZeel mode of transmitting the
audio signal. When used in conjunction
with the NHB-18NS preamplifier, the
line is fully impedance matched and all
possible echoes are eliminated, bringing
an unprecedented level of transparency.
As the input impedance will be 50 ohms
only specifically designed preamplifier
can drive it.
Press OK to confirm the input selection.
Press X to return to input selection
mode.
Press X once again to return to main
Menu.
This input is single ended, 30 kohms
impedance. It is paralleled to the BNC
input but the 50 ohms resistor is lifted.
If your preamplifier has single ended
RCA outputs, please give this input the
preference choice because of the
simplified signal path.
Press OK to confirm the input selection.
Press X to return to input selection
mode.
Press X once again to return to main
Menu.
This input is truly and actively
balanced, using a translator balanced to
unbalanced dedicated circuit.
If your preamplifier is only fitted with
XLR outputs, use it.
Ultimate performance will be slightly
reduced because of the additional
junctions present in the signal. However
the loss will be extremely small
considering the care taken during design
process.
Press OK to confirm the input selection.
Press X to return to input selection
mode.
Press X once again to return to main
Menu.
10.3. Menu Output
Here you can change the overall
amplification gain.
Press OK to confirm or use the arrows
to select the desired gain, and press OK
again for confirming the new setting.
Factory default is 32 dB.
Press X to exit the Output menu.
►
◄
MENU
1 Display 4 Trigger
2 Input 5 Diag
3 Output
1 2 3 4 5
INPUT
◄ Select ►
ZEEL
◄►RST OK X
INPUT
◄ Select ►
RCA
◄►RST OK X
INPUT
◄ Select ►
XLR
◄►RST OK X
INPUT
◄ XLR Pin 1 ►
Chassis
◄►RST OK X
MENU
1 Display 4 Trigger
2 Input 5 Diag
3 Output
1 2 3 4 5
OUTPUT
◄ Amplifier Gain ►
+32 dB
◄►RST OK X
OUTPUT
◄ Amplifier Gain ►
+26 dB
◄►RST OK X

darTZeel NHB-458 User Manual, version 1.0 Page 14 of 19
10.4. Menu Trigger
This menu allows for automatically power the NHB-458 ON, either when using the NHB-18NS preamplifier, or
when music is played. It also allows for daisy chain several NHB-458 for powering them ON in sequence.
END OF PRELIMINARY
MANUAL
You can choose the illumination brightness.
Press OK to confirm brightness setting, and
then use the "+" and/or "-" keys to choose
between 25, 50, 75 or 100%. Press OK again
to memorize the brightness level.
Press X to return to the upper level, allowing
for choosing another parameter.
Suggested setting: 25% in order to save
display life time.
Here you can choose display Auto-
off time, provided you previously
selected this function via the direct
access key (see cahpter 9.2).
Press OK to enter into the Auto-off
time sub menu, then press "+"
and/or "-" keys to select the
desired time, and then confirm
with OK.
Press X to return into navigation
level stage.
After selecting “Rename” from the
above PARAMETERS menu, the
default input source displayed is the
one you have selected for listening.
MENU
1 Display 4 Trigger
2 Input 5 Diag
3 Output
1 2 3 4 5
TRIGGER SETTINGS
◄ Trigger IN ►
OFF
◄►RST OK X
TRIGGER SETTINGS
◄ Select ►
RCA
◄►RST OK X
TRIGGER SETTINGS
◄ Select ►
XLR
◄►RST OK X
INPUT
◄ XLR Pin 1 ►
Chassis
◄►RST OK X

darTZeel NHB-458 User Manual, version 1.0 Page 15 of 19
Press ▲ or ▼ in order to change the source
to be renamed.
Press ◄ or ► to select the character
(alphanumeric key) to be changed.
Press + or – in order to browse from A-Z
and 0-9. Space (blank) is just before “A”.
Press OK to confirm the new name.
Press RST and OK in order to return to the
factory default name.
After selecting “Settings” from the above
PARAMETERS menu, the default input
source displayed is the one you have
selected for listening.
Press ▲ or ▼ to select another source.
Press + or – in order to adjust the input
level.
The range is from -10dB to +10dB.
Press OK to memorize the level.
Press RST to return to 0dB.
Press ► to set Input balance, hereunder.
Altering the default balance for a source can
be helpful when a particular source, such as
a phono cartridge, exhibits a channel
unbalance.
Press + or – in order to adjust the input
balance.
The range is from 9.5dB Left to 9.5dB
Right.
Press OK to memorize the balance setting.
Press ▲ or ▼ to select another source.
Press RST to return to 0dB.
Press ► to set Input mode, hereunder.
Altering the input mode for a source can
be helpful for a monophonic source such
as an old AM tuner, or a mono or 78-rpm
phono cartridge.
Press + or – in order to toggle between
Stereo and Mono.
Press OK to memorize the input mode.
Press ▲ or ▼ to select another source.
Press RST to return to Stereo.
Press ► to set Input bypass, right after.
The “USER INFORMATION”
screen indicates the serial number
of your NHB-458, as well as your
registered name.
Please be sure the registered name
corresponds to yours.
If the registered name is not correct,
immediately contact your dealer.
An improper registered name will
void access to warranty rights.
Used for Home Theatre systems.
The gain of the bypassed source is 0dB.
WARNING
Pleasure Control will be bypassed!!!
Press + or – in order to toggle
between bypass On and Off.
Press OK to memorize.
P
ress ▲ or ▼ to select another
source.
Press RST to return bypass to Off.
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darTZeel NHB-458 User Manual, version 1.0 Page 16 of 19
This is the maximum level at which your
NHB-458 will power on.
In the above example, if - and only if - you
listened at more than -26dB, the output level
will resume to this value at the next start.
Press + or – to set the desired level.
Press OK to store this value.
Press RST to restore the factory default.
Press ► to set the source.
The NHB-458 will always start with a
preferred source, that is, whichever source
was selected during last powering off.
“No change” means the NHB-458 will start
with same selected source as played during
previous music session.
Press + or – to choose a source to be played
at power on.
Press OK to save this setting.
Press RST to restore the factory default.
Press ► to set the internal power amp.
When using the NHB-458 as a stand-alone
preamplifier, the power-amplifier section
will be shut off, improving both electricity
consumption and signal-to-noise ratio.
Press + or – to enable or disable the internal
power amplifier.
Press OK to confirm.
The NHB-458 will shut down and restart.
Allows for 3 different types of attenuation.
This can be useful when you just want to
decrease the level instead of cutting it off
completely.
Press + or – to set the Mute level:
∞ → -20dB → -40dB
Press OK to memorize this setting.
Press ► to set the Volume limit.
Enables/disables a maximum output level.
Very useful for not overloading low power
rated speakers, or simply allowing your kids
to play with your system without shaking
neighbors’ walls!
When left to Off, pressing ◄ or ► will go
back to above “Mute level” screen.
Press + or – to set to On.
Press ► to set the new value in the next,
hereunder screen.
In the sample screen above, the maximum
output level has been set to -2.5dB.
Press + or – to set the desired value.
Press OK to store it.
Press RST to return to +12dB default.
When max volume has been set, there is no
need to reset the value when you do not
want to use a limit, you simply enable or
disable it.
Go to previous page Clock & Diag
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darTZeel NHB-458 User Manual, version 1.0 Page 17 of 19
If you have to set both the time and the date,
it will be easier first to set the date, and then
the time.
Press + or - to set the correct hour.
Press ► to jump to the minute figures.
Press + or – to set the correct minute.
Press OK to save.
The time clock will synchronize at the
moment you press OK. Until you press OK,
the internal time clock will not be changed.
Press ▲ or ▼ in order to display the next
screen, for date setting.
The date format is DD.MM.YYYY.
This rubric cannot be changed. Sorry if you
are used to another format, but this is the
most universal one.
Press + or - to set the correct day.
Press ► to jump to the month figures.
Press + or – to set the correct month.
Press ► to jump to the year figures.
Press + or – to set the correct year.
If the time has not been set yet:
Press ▲ or ▼ to return to “Set time”, and
adjust the time.
The date settings will be kept correct, saving
you from entering the “Set Clock” menu
twice.
Press OK to save.
When “Auto start” is set to On, your NHB-458
will power itself on at the time programmed
on the next screen shown below.
When “Auto start” is left to Off, your NHB-
458 will not start automatically.
Press + or – to set “Auto start” to On or Off.
Press ▲ or ▼ to go to the next menu, to set
the start time.
Press + or - to set the correct hour.
Press ► to jump to the minute figures.
Press + or – to set the correct minute.
Press OK to save.
The STOP TIME procedure is exactly the
same as START TIME.
Press “Stop time” from the main CLOCK
menu in order to proceed.
This screen indicates the software
version and the registration status.
DTZ: When your machine is new,
you will need to register it.
Insert your USB key into the
rear panel port, and press DTZ.
BKP: This feature allows copying
internal NHB-458 parameters
onto the USB key, for factory
diagnosis.
Insert your USB key into the
rear panel port, and press BKP.
UPD: Used for updating the internal
NHB-458 firmware.
Insert your USB key into the
rear panel port, and press UPD.
Your USB key must contain the
appropriate file in order to operate
properly.
Further details about key activation
procedure are described in chapter 7.
Go to
Page 11
See Start time

darTZeel NHB-458 User Manual, version 1.0 Page 18 of 19
11. Some advice and tips
11.1. Cleaning and upkeep
The darTZeel NHB-458 has not only been designed to
provide you intense moments of musical pleasure; it
also has been designed to withstand the rigors of
time – assuming that you take proper care.
The entire Swedish-steel case functions as a heat
exchanger, while the two internal lateral heat sinks
regulate and maintain the correct temperature. The
vent slots provide heat dissipation, but they do not
communicate with the inside of the machine.
Therefore, the NHB-458 is virtually dust-proof.
It is not recommended to clean internal parts.
Actually, we do not recommend ever removing the
top cover!
As for the external parts of your machine, a soft cloth or
even a dust brush will be completely adequate.
In case of fingerprints, a gentle rub with a cloth
soaked in isopropyl alcohol should be sufficient.
Just bear in mind, however, that the simplest things are,
more often than not, the most efficient.
We personally find that a spot of mild soap on a wet
soft cloth is the best method most of the time. Try
for yourself!
As you have certainly guessed, we confirm that it is
strongly recommended to never use acid to clean
your gear. Acid is very corrosive and could react
with the front plate’s anodized coating.
Furthermore, acid is very corrosive for the skin, too…
If you follow these few elementary rules, you will
be assured of having a very nice-looking machine
for years to come.
11.2. What not to do
Our advice and recommendations have been
intentionally placed close to the end of this user’s
manual. That does not mean that they are of only
minor importance – quite the contrary.
We just thought that the following points are not
directly involved in the everyday use of your
amplifier.
However, operating the darTZeel NHB-458 calls for
certain precautions.
The few but important warnings are the following:
•Never, ever attempt to short-circuit the Speaker
Binding Posts.
•Repeated short circuits will lead to permanent damage
to the corresponding output stage.
•When bi- or tri-cabling, be especially careful when
connecting the cables. If you inadvertently cross
the polarity of one run regarding the other(s),
you will make a perfect short circuit. This can
easily destroy the corresponding output stage!
The warranty will be partially or totally void
in the event of non-compliance with the
above!
•Never forget to power off your darTZeel NHB-458
before connecting or disconnecting any source or
loudspeakers.
•Never use a “contact enhancer” such as silver
paste on the input terminals or speaker binding
posts, as this may cause a short circuit and
catastrophic failure.
12. Assistance
If you need any commercial or technical information
about the darTZeel NHB-458, or if you have any
difficulties or enquiries, please contact us by email
at
[email protected]
You can of course write us at the following address:
darTZeel Audio SA
2, chemin Louis-Hubert
CH-1213 Petit-Lancy
Geneva/Switzerland
We also invite you to visit our website at
www.darTZeel.com
We wish you countless hours of musical delight
with your NHB-458.We hope that you will have no
further need to read this manual, except for the
pleasure…
Your darTZeel team

darTZeel NHB-458 User Manual, version 1.0 Page 19 of 19
13. Technical data
darTZeel NHB-458
Nominal output power : 200 watts RMS (230 watts peak) @ 8 ohms.
330 watts RMS (360 watts peak) @ 4 ohms.
330 watts RMS (400 watts peak) @ 2 ohms (software limited).
Line Gain : 12 dB nominal, up to 22dB.
Power Stage Gain : 26 dB @ 8 ohms.
Input impedances : Phono MM*= 47 kohms. Neumann RIAA 4th pole included.
Phono MC*= 1 kohms. Neumann RIAA 4th pole included.
RCA: > 30 kohms.
Zeel BNC: 50 ±1 ohm.
XLR: > 15 kohms between Pin 1 and 2.
> 15 kohms between Pin 1 and 3.
Line output impedances : RCA = 75 ohms, darT BNC = 50 ohms
Speaker output impedance : < 0.33 ohms, from 20 Hz to 20 kHz (measured under 8 ohms).
Frequency response : 3 Hz to 300 kHz, +0, -6 dB.
20 Hz to 20 kHz, +0, -0.5 dB.
20 Hz to 50 kHz, ±0.5 dB.
Rise time : < 0.8 µs.
Slew rate : > 88 V/µs, peak-peak.
DC output voltage : < ±15 mV max.
Total Harmonic
Distortion (THD) : < 1 % from 7 Hz to 77 kHz
Temporal Distortion : None, at any level and load, as specified above.
Crosstalk : < -90 dB from 20Hz to 20kHz.
Signal to noise ratio : > 115 dB (A) @ nominal power.
Power consumption : 3 watts Standby, 40 watts @ idle, 1000 watts @ maximum output power.
Size in mm : 440 x 335 x 170 (WxDxH). Total deep with handles: 415 mm.
Net weight : 28 kg.
* Phono inputs are optional and are not installed in standard delivery.
darTZeel amplifiers are made to last forever by
darTZeel Audio SA, in Geneva Switzerland.
darTZeel Audio SA www.dartzeel.com
2, chemin Louis-Hubert
CH-1213 Petit-Lancy / Genève [e-mail]
Suisse