darTZeel NHB-108 model one
User Manual, version B 1.0
Page
20
of 35
5mm thick bottom plate, in the form of a sandwich.
All cables and wires are routed in this sandwich,
minimizing the influence of electromagnetic fields.
Furthermore, such an arrangement is of extreme
rigidity ensuring exceptionally good mechanical
coupling between the mother plate and heat sinks
modules.
T4.2. Divide to conquer
The inside of the
NHB-108 model one
is divided
into four distinct volumes. The left and right chan-
nels are insulated from each other, as are their re-
spective power supplies. This unprecedented con-
struction allows extremely low crosstalk behavior
across the whole audio frequency range. You are
either true dual mono, or you are not. The
darTZeel
NHB-108 model one
definitely is.
The two front compartments are devoted to the
power supplies, and are themselves divided into a
two-storey structure. The Crowbar elements and the
soft start circuitry are located on the lower level,
while the suspended toroidal transformers are fixed
on the 6mm thick, upper decks.
We insist on the fact that in the final assembly
process, all parts are precisely aligned by means of
cotter pins, like in Swiss precision clockwork
movements, before being tightly screwed together.
This additional precaution adds still more rigidity,
and the entire case then behaves as a single block.
As a free bonus, the case is thus virtually dust
proof.
T4.3. Eliminating vibrations
The fastening of the power supply transformers was
carefully thought out as regards noise reduction and
trouble-free life. A specially developed suspension
ensures that even in case of failure, the transformers
will not fall off.
So, in 40 or 50 years, when the rubber absorbers
have become – perhaps – worn out, they will with-
stand their last trip to the factory for their replace-
ment.
The same is true for the silentblocs used for sus-
pending the lighter audio and monitoring circuits.
These various suspensions, tuned on different reso-
nance frequencies, are coupled quite tightly to the
chassis, absorbing especially the medium and high
frequencies, most important in terms of sound re-
production accuracy.
And while on this subject, have you ever heard an
amplifier
singing
? This can occur when the transis-
tors of the final stages and/or the power transform-
ers are not properly decoupled.
They start to vibrate at the excitation signal fre-
quency – in this case the music – this vibration
interfering with the
electrical
origin of the signal.
You can hear it if the amp is hooked to a dummy
load, since in normal use, loudspeakers fortunately
mask this disconcerting internal “singing”.
No such mechanical singing on the
NHB-108
model one
! The electric signal is transmitted stage
to stage, from input to output, free from any me-
chanical disturbance, internal or external.
The
NHB-108 model one
stands on 3 pads incor-
porating rubber inserts. Oddly enough,
very few
manufacturers rely on 3 legs instead of four. We
can recall that the Lunar Explorer Module (LEM)
also had three legs, but that is another story after
all.
Weighing around 30kg, the
darTZeel
(not the LEM)
needs to have a good stable base. Those three pads
are evenly located around the horizontal center of
gravity of the amplifier, ensuring excellent stability
on virtually any surface.
The absorbing rubber pads dampen the lower fre-
quencies, thus forming the ideal complement to the
suspensions described earlier. In the case where you
would want to use 2, 3, or even 4 stacked
darTZeel
NHB-108 model one
units, we can make on spe-
cial request pads of different diameter to maintain
the very same vibrational absorption behaviour.
These pads are easy to install and can be purchased
separately.
T4.4. Everything is transparent
The
NHB-108 model one
cover is made of 8mm
thick tempered, bronze-smoked glass. It harmonizes
magnificently with the colours of the housing, and
gives an inimitable touch.
The glass is held by a single, central 24k gold
plated screw, and rests on a dedicated, cut-out rub-
ber seal, giving to
NHB-108
its dust proof quality.
Your machine will therefore remain as new for
years to come.
The reason why we did not choose a metal cover is
not so obvious as it might appear. It is true that to
look through the glass of the
darTZeel NHB-108
model one
is a pleasure for the eyes. Look at those
24k gold plated, 5mm thick pure copper Moon-
crescent shaped bar busses, and tell us frankly what
you feel…
There are also a couple of technical advantages that
glass has over metal.
Its crystalline, inert structure, combined with the
rubber foam seal, functions as an internal noise
killer.
And contrary to metal, glass is totally transparent to
magnetic fields, thus avoiding the inherent mag-
netic loop that metal would induce over the power
supply transformers. Last but not least, the internal
housing is much less polluted by magnetic ghosts.
