darTZeel NHB-108 Model One-Mk2 Owners manual
NHB-108 model one
User Manual
Version B
darTZeel NHB-108 model one User Manual, version B 1.0 Page 2 of 35
Table of contents
First Section, User Manual
1. Introduction .......................................................................................................5
2. Brief description................................................................................................5
3. The NHB-108 in details......................................................................................6
3.1. Front Panel..................................................................................................................................... 6
3.2. Rear Panel ...................................................................................................................................... 6
3.3. Top View ........................................................................................................................................ 7
4. Who am I? ..........................................................................................................8
5. Connecting and setup.......................................................................................8
5.1. Important prior notice .................................................................................................................... 8
5.2. Location ......................................................................................................................................... 8
5.3. Speaker impedance ........................................................................................................................ 8
5.4. Choice of the input......................................................................................................................... 9
5.5. Powering ON ................................................................................................................................. 9
6. Using the darTZeel ............................................................................................9
6.1 Power cycle.................................................................................................................................... 9
6.2. darTZeel's Eyes.............................................................................................................................. 9
6.3. User parameters ........................................................................................................................... 10
6.4. Jumper settings............................................................................................................................. 11
7. Maintenance.....................................................................................................11
7.1. Fuse(s) replacement ..................................................................................................................... 11
7.2. DC voltage drift ........................................................................................................................... 13
7.3. Cleaning and upkeep.................................................................................................................... 13
8. Some advice and tips......................................................................................13
8.1. What not to do.............................................................................................................................. 13
8.2. Troubleshooting ........................................................................................................................... 14
8.2.1. Eyes Closed.................................................................................................................................. 14
8.2.2. Blinking Eyes............................................................................................................................... 14
8.2.3. Amplifier ON, no sound............................................................................................................... 14
8.2.4. Warped sound .............................................................................................................................. 14
8.2.4. Sensitive fuses.............................................................................................................................. 14
8.2.5. Sound too quiet ............................................................................................................................ 15
8.2.7. Melting Fuse(s) at power ON....................................................................................................... 15
8.2.8. RAS (Regular And Satisfactory).................................................................................................. 15
9. Conditions of warranty ...................................................................................15
9.1. Breakdowns or faulty parts .......................................................................................................... 15
9.2. Conditions of use ......................................................................................................................... 16
10. Assistance .......................................................................................................16
11. Technical data..................................................................................................17
darTZeel NHB-108 model one User Manual, version B 1.0 Page 3 of 35
Technical Section
T1. Introduction .....................................................................................................18
T2. Genesis of NHB-108 ........................................................................................18
T3. Criteria..............................................................................................................19
T4. Structural aspects ...........................................................................................19
T4.1. The case modules......................................................................................................................... 19
T4.2. Divide to conquer......................................................................................................................... 20
T4.3. Eliminating vibrations.................................................................................................................. 20
T4.4. Everything is transparent..................................................................................... 20
T4.5. TIO, Totally Identified Object ..................................................................................................... 21
T5. The audio electronics......................................................................................21
T5.1. What is distortion? ....................................................................................................................... 21
T5.1.1. Keeping in harmony..................................................................................................................... 21
T5.1.2. Inter Modulation Distortion ......................................................................................................... 22
T5.1.3. Temporal Distortion..................................................................................................................... 22
T5.2. What application field? ................................................................................................................ 23
T5.2.1. IGBTs........................................................................................................................................... 23
T5.2.2. FETs............................................................................................................................................. 24
T5.2.3. Bipolars........................................................................................................................................ 24
T5.3. The circuit of darTZeel ................................................................................................................ 24
T5.3.1. Criteria of choice.......................................................................................................................... 24
T5.3.2. darTZeel schematics .................................................................................................................... 25
T5.3.3. Component layout........................................................................................................................ 25
T5.4. Symmetrically balanced? ............................................................................................................. 26
T5.4.1. From the microphone… ............................................................................................................... 26
T5.4.2. To the loudspeakers… ................................................................................................................. 26
T5.4.3. And into the air… ........................................................................................................................ 26
T5.4.4. Via the darTZeel .......................................................................................................................... 27
T5.5. darT to Zeel 50Ω .......................................................................................................................... 28
T6. Onboard safety ................................................................................................29
T6.1. Crowbar circuit ............................................................................................................................ 29
T6.1.1. Crowbar activation....................................................................................................................... 29
T6.1.2. Crowbar cycle .............................................................................................................................. 29
T6.2. Supervision system ...................................................................................................................... 30
T6.2.1. Current sensing ............................................................................................................................ 30
T6.2.2. For its eyes only ........................................................................................................................... 30
T7. Power supplies ................................................................................................30
T7.1. From mains to loudspeakers......................................................................................................... 30
T7.2. Voltage or current?....................................................................................................................... 31
T7.3. Received idea............................................................................................................................... 32
T8. The sound of darTZeel ....................................................................................32
T9. Reliability .........................................................................................................32
T9.1. Quantified longevity .................................................................................................................... 32
T9.2. Long term availability.................................................................................................................. 33
T9.2.1. Spare parts.................................................................................................................................... 33
T10. The next darTZeel............................................................................................34
T11. Keeping an open door.....................................................................................34
T12. Special adjustments........................................................................................35
T12.1. Output DC voltage drift ............................................................................................................... 35
T12.2. Monitoring circuit ........................................................................................................................ 35
darTZeel NHB-108 model one User Manual, version B 1.0 Page 4 of 35
darTZeel NHB-108 model one
Version B
User Manual
1. Introduction
Congratulations for purchasing a darTZeel NHB108 model one.
Our machines are designed and hand built for very
long lasting use and musical pleasure.
The darTZeel NHB-108 model one is a highly
unusual power amplifier, and requires special care.
We strongly recommend you read this manual in its
entirety, in order not to miss any reason for enjoy-
ing your machine at its very best!
When opening the crate, you certainly noticed the
three separate information sheets. They are of primary importance and you must read them without
fail before continuing.
These documents are:
- The warning notice, printed in red.
- The “3-step-to-go” commissioning leaflet,
printed in blue.
- The packing/unpacking notice, printed in green
While humor is truly part of our philosophy, please
keep in mind that all our warnings must be taken
into account, for the sake of your own safety.
If you carefully follow all the instructions herein,
you will be rewarded by very long, joyful listening
sessions, for years and years to come.
Please carefully keep all documentation and packing material in a safe place, especially the crate, in
case you have to move house one day.
2. Brief description
The darTZeel NHB-108 model one is the pinna-
cle of more than 16 years of research & development, with the first goal in mind being sound reproduction, nothing but sound reproduction.
Every basic element of the darTZeel NHB-108
model one was chosen for its high intrinsic sound
qualities. No compromise about the cost price was
even contemplated.
The result is what you can see, touch and hear…
right now.
One of the secrets of the darTZeel NHB-108 model
one can be found in two words:
Passion and Love… The passion for sound, of
course, and love of music, needless to say…
As for the rest, we just put in few electronics, a wee
bit of mechanics, and an awful lot of working
hours.
If you want to know more about the technical side
of the darTZeel NHB-108 model one, we invite
you to read the dedicated section at the end of this
manual, in which you should find much of interest.
darTZeel NHB-108 model one User Manual, version B 1.0 Page 5 of 35
3. The NHB-108 in details
3.1. FRONT PANEL
1. Identification Plate
2. The Eyes
3. The Power Nose
3.2. REAR PANEL
4. 50Ω BNC Zeel Inputs
5. RCA Inputs
6. Speakers Terminals
7. XLR Inputs
8. IEC Power Socket
9. Input Impedance Selector
darTZeel NHB-108 model one User Manual, version B 1.0 Page 6 of 35
3.3. TOP VIEW
10. DC Offset Trimmer
11. Jumpers
12. Speaker Impedance Switch
13. Fuse Holder
14. Operating Voltage Selector
darTZeel NHB-108 model one User Manual, version B 1.0 Page 7 of 35
4. Who am I?
Your darTZeel NHB-108 model one bears, on its
front panel, its Identification Plate (1). On this 24k
gold plated brass plate are engraved your name, and
the serial number. Do not unscrew the plate since it
is the identity card of your machine!
The serial number can be read as follows:
TZ-XY1081.dcbZ
X = Century of making
Y = Batch number
dcb = Identity in the batch number
Z = Version (A or B)
Example:
The sample bearing the serial number
TZ-UC1081.001B
Is the first machine of the third batch, made in the
st
21
century, and of version B. This numbering is
thus valid until the end of the 26
From the second batch, we chose to manufacture
only the darTZeel NHB-108s in version B. Actu-
ally this version even offers some slight improvement over the version A. If you want to know how
the version A differs, please visit our website at
www.darTZeel.com, where you can download the
previous manuals.
It is vital to bear in mind all the following notes
and remarks concerning the use of your
darTZeel NHB-108 model one.
Thank you.
th
century.
5. Connecting and setup
5.1. Important prior notice
In order to protect the loudspeakers, your darTZeel
NHB-108 model one features a special monitor-
ing circuit. If any abnormal situation is detected,
this circuit will intentionally melt the power fuse(s).
This behaviour is not be interpreted as a failure.
The NHB-108 has been designed to behave this
way, in line with our philosophy of not spoiling the
sound by adding any protection circuit in the signal
path. If you want to know more about this specific
circuit, also called Crowbar, please refer to the
technical section, in chapter T6.
5.2. Location
Before making the first connection, you should
think carefully about the location where you are
going to put your gear. If you planned to fit your
darTZeel NHB-108 model one into furniture,
please bear in mind that you must allow at least one
inch of free space all around the unit, for proper
cooling.
If you do not respect this, the darTZeel NHB-108
model one may stop playing if it becomes too hot.
The heat sinks shutdown point is at around 70°C,
and the power supply starts up again when the temperature has dropped to 55 °C.
Please also note that permanent excessive temperature will reduce the life span of your machine. Read
the technical section at the end of this manual if you
want to learn more about this topic.
Anyway, if possible, always leave enough space
around your darTZeel NHB-108 model one, allow-
ing you to gain easy access to it when making connections.
5.3. Speaker impedance
The darTZeel NHB-108 model one can drive virtu-
ally any loudspeaker, provided its nominal impedance is between 1.5 and 8 ohms. Above 8 ohms,
maximum available power output will be slightly
reduced, but without any sound quality loss.
Nominal standardized impedance can vary by ±
20%, and can thus reach the following critical
minimum values:
6.4Ω in the case of 8Ω speakers
3.2Ω in the case of 4Ω speakers
1.6Ω in the case of 2Ω speakers
If your loudspeakers are between 3Ω and 8Ω,
which is nearly always the case, you can directly
hook them to the Speaker Terminals (6).
Black terminal (upper) = Ground.
Red terminal (lower) = Live signal.
If your loudspeakers impedance is less than this, or
if you want to parallel 2 pairs of 4Ω speakers, you
must go to chapter 6.3. "User parameters" before
you consider going further.
If you do not respect the above, you may encounter
some blown fuses when playing music at loud levels.
CAUTION: You must connect your loudspeakers to
the Speaker Terminals (6) before powering ON
the darTZeel NHB-108 model one!
darTZeel NHB-108 model one User Manual, version B 1.0 Page 8 of 35
5.4. Choice of the input
Only one input can be used at a time. All inputs are
paralleled, so you cannot select them separately.
If you do not own a darTZeel NHB-18NS pream-
plifier yet, we suggest you use either RCA (5) or
XLR (7) inputs, with the Input Impedance Selector (9)
switched on "RCA Hi Z" (mid position, physically
speaking), or "XLR Bal". (lower position), respectively.
The XLR inputs are truly balanced on the version
B, through floating transformers:
Pin 1 = Ground
Pin 2 = Hot leg
Pin 3 = Cold leg.
If you have already paid us the honour of purchasing
a darTZeel NHB-18NS preamplifier, we strongly
recommend using the 50Ω BNC Zeel Inputs (4),
with the Input Impedance Selector (9) switched on
"Zeel 50Ω"(upper position, physically speaking).
The Zeel input is definitely the one that will bring
you the purest sound ever achievable. Read the
technical section at the end of this manual if you
want to know more about this topic.
5.5. Powering ON
Please do not forget that the darTZeel NHB-108
must have loudspeakers connected before you
power ON.
Your machine has already been factory set in order
to adapt to your mains supply, as confirmed by the
3-Step-To-Go commissioning leaflet. In case of
doubt, please contact us.
Connect the supplied power cable into the IEC
socket (8) and plug the other end into the mains
wall outlet.
You can then power ON the darTZeel NHB-108
model one by pushing the Power Nose (3) button.
If a source is already connected, you should immediately hear the music.
When powering the amplifier OFF by pressing the
Power Nose (3) button, you can still hear the music
for 10 to 30 seconds before the level goes down
dramatically and stabilizes. This behavior is perfectly normal, and it is not a failure at all. If you
need more details about this, please refer to the
technical section.
6. Using the darTZeel
6.1 Power cycle
The darTZeel NHB-108 model one has been de-
signed to deliver more than 90% of its magical
sound at cold start.
After 5 minutes, you are very close to the best the
machine can offer. The increasing quality you may
hear as time goes by will be mostly the reflection of
your growing musical pleasure…
No need then to leave your machine powered ON
all the time, except of course if you like paying
bigger electricity bills…
If your present preamplifier produces some clicks
and/or bumps when powering on/off, we suggest
you observe the following sequence:
Powering ON: first the Preamp, then the darTZeel
NHB-108 model one.
Powering OFF: first the darTZeel NHB-108 model
one, then the preamplifier.
If this procedure is not respected, you may encounter some blown fuses due to Crowbar triggering.
If you still hear some thumping at powering OFF,
you will have to wait around 10 seconds before
switching the preamplifier OFF. This noise, however, will be inconsequential and harmless.
6.2. darTZeel's Eyes
The 2 giant orange LEDs, called Eyes (2) for obvious reasons, are fully featured function indicators.
Five different illumination states, for each individual channel, are described hereunder:
1) Eyes shut (light off). This is of course the
status when the darTZeel NHB-108 model one
is either powered off or not plugged in. If one
Eye only is shut, it means that there is a power
fault or a blown fuse in the channel in question.
In the latter case, please go to chapter
7.1."Fuse(s) replacement".
2) Idle state. 45 to 55 seconds after powering ON,
and with no input signal, the Eyes go into this
barely illuminated state.
3) Signal presence. When an input signal, corre-
sponding to over 10 mW at 8Ω is detected, the
Eyes illuminate fully. You are in "musical
cruise mode". When the input signal disappears
for more than 45 to 55 seconds, the Eyes go
back to idle state. While listening at very low
levels, Eyes could toggle between states 2 and
3; this is normal behaviour.
4) Clipping. When approaching maximum output
power, the corresponding Eye flashes brightly
for about half a second, and then goes back to
the "musical cruise mode".
5) Blinking. Please refer to chapter 8.2.2. "Blinking
Eyes".
darTZeel NHB-108 model one User Manual, version B 1.0 Page 9 of 35
6.3. User parameters
The darTZeel NHB-108 model one must be cor-
rectly set, accordingly to the loudspeakers' nominal
impedance. Your machine is already factory set for
speakers having nominal impedance from 3Ω to
8Ω, as is usually the case.
If your loudspeakers' nominal impedance is between 1.5Ω and 2.5Ω, or if you connect two paral-
leled 4Ω speakers, you must adapt your NHB-108
to that load. If you want to know more about this
special mode, please refer to the technical section.
The procedure for the adaptation of the output impedance is described hereunder:
Power the machine OFF.
!!! UNPLUG THE AC CORD FROM THE WALL,
and please wait for 5 minutes !!!
Disconnect all links you may have installed by
removing all cables from inputs (4), (5) or (7), and
from Speakers Terminals (6). Unscrew the single
central cover screw, and remove the smoked glass
using the supplied suction grips, as shown in fig.1
Gently wet them in order to get firm vacuum.
Please be very careful when removing the cover,
since it is real tempered glass, not Plexiglas
Fig.1 – Suction grips
tm
.
The speaker's impedance switch is located at the
upper left of the transformer (upper right for the
right channel),
Fig.2 – Speaker's impedance switch
as shown in Fig.2
When the switch is pointing towards the front plate,
you are in Lo mode, suitable for 1.5Ω to 2.5Ω
speakers. In this mode, you can also parallel 2 pairs
of 4Ω speakers.
By flicking the switch towards the rear panel direction, you set the Hi, default mode, for speakers of
3Ω or more. This is the most often used configuration.
The darTZeel NHB-108 model one being a true
dual mono design, you can also use it to biamplify
hybrid loudspeakers (having different technology
and impedance drivers, i.e. an 8Ω woofer and a 2Ω
tweeter) by switching one channel to Hi and the
other one to Lo, respectively.
Please bear in mind that in this case, you will need
two NHB-108 model one, one for each loudspeaker.
Once you have chosen your configuration, you can
carefully put the glass cover back, and screw it on
again as follows:
Freely hand screw until you feel the thread-end
resistance. Then use the supplied screwdriver and
turn an extra 1/8 turn approximately. The screw
must be sufficiently tightened to prevent the possibility of the glass rotating around the screw axis.
Then reconnect all the wires and cables, paying
special attention to the loudspeaker cables. They
must be hooked to the Speaker Terminals (6) before powering the amplifier ON.
Now just sit back and relax, and immerse yourself
in pure musical pleasure!
darTZeel NHB-108 model one User Manual, version B 1.0 Page 10 of 35
6.4. Jumper settings
Before making any change in the jumper settings, power off the amplifier, REMOVE the AC
cord, and wait for 5 minutes before removing
the glass cover.
On the inside rear panel (see chapter 3.3. "Top
View", no. 11), where the input circuit boards are
located, you will see 3 jumpers per channel:
Fig.3 – Jumpers
2 jumpers are labeled Ground LIFT and XLR pin
1 FLOAT. They can be changed over in the event
of a hum problem when an XLR input is used, depending on the circuit design of the associated preamplifier. In a lesser extend, these jumpers may
also affect RCA inputs. Their factory default position is the most commonly used in order to obtain
best results.
The third jumper, labeled DC Offset COMP is the
most important one since it does affect the sound of
the amplifier.
This jumper is set to ON at the factory, preventing
any problem of DC offset due to AC voltage variation or too great an ambient temperature change.
If your AC mains voltage is stable, and your listening room is at standard temperature, we recommend
removing the compensation by putting the jumper
to off.
In doing so, you will fully benefit from the very
philosophy of the NHB-108 model one, which is
to refuse any compensation or global negative feedback which could impair the sound. Most users
have reported to us that this setting has the best
sound. Depending on your own audio system, this
result may vary, however, so experiment for yourself.
7. Maintenance
7.1. Fuse(s) replacement
The following procedure concerns the left channel.
For the right channel, the procedure is the same but
that the fuse is in a mirror image configuration.
If one – or both – fuse(s) has/have blown, first try
to determine the cause.
The Crowbar circuit installed in the darTZeel
NHB-108 model one causes fuses to melt when an
abnormal situation is detected. This is normal behaviour.
For more information about this topic, please refer
to the technical section, chapter T6.
If a newly replaced fuse immediately melts when
you power on your NHB-108 model one, even
though your speakers are correctly connected to the
Speakers Terminals (6), unplug the AC mains and
contact us directly:
troubles@dartzeel.com
Hereunder is the procedure:
In order to change a fuse, power off your NHB-108
model one by pressing the Power Nose (3) button.
!!! UNPLUG THE AC CORD FROM MAINS, and
Remove all the input and output connections.
Remove the single central screw located on the top
smoked glass cover. Take the two supplied suction
grips, slightly wet them in order to provide strong
vacuum, and firmly apply them on the cover glass,
as indicated in Fig.1
Please be careful when removing the top cover,
since it is of real glass, not Plexiglas
Put the amplifier on a carpeted surface, and gently
(but firmly, as it is a heavy, 30kg electronic creature) pivot it vertically onto its front handles. Use a
protective cloth as indicated in fig.4 in order to
avoid scratching the inside aluminum parts
wait for 5 minutes !!!
Fig.4 – Soft cloth
TM
.
darTZeel NHB-108 model one User Manual, version B 1.0 Page 11 of 35
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