User Manual

darTZeel NHB-108 model one Audiophile's technical manual Page 23 of 28
8. The sound of darTZeel
It is always hard to define objectively
what we perceive subjectively, isn't it?
How to enjoy an excellent glass of wine,
if not sharing it with friends?
We could say that the darTZeel NHB-108
model one offers an outstanding temporal
linearity, allowing true three-dimensional
re-creation.
We also could say that the bass is
deeper than the Mariana Trench, with
every nuance incredibly rendered.
We could add that voices are so sweet
and timbres so accurate that you will
turn your head, believing that someone
has just entered the room.
We could even conclude that no cymbals
can be better reproduced than through
our machine.
Instead, we will just invite you to take a
seat and listen to some good music…
After all, if you read this manual, you
certainly already own a darTZeel NHB-108
model one, and you know better than
anyone what we are talking about. So
why do we need to produce any further
advertising? In fa ct, just for the fun of it.
And music is fun too, isn't it?
9. Reliability
9.1. Quantified longevity
"How long does a darTZeel NHB-108 model
one last? Before first failure?"
Well, let’s us try to see a bit more
clearly, and seek a better understanding
of the different causes of failure…
Assuming that the first possible failure
will be due to the weakest component,
we could be tempted to install only the
longest lasting components.
Is the first criterion, "Purity", compatible
with "Reliability"? If a component lasts
twice as long as another, but sounds
twice as bad, what would be the lesser
evil?
Before giving a firm answer, it is inter-
esting to ask ourselves what are the
most influential parameters affecting the
life span of a given component. Several
studies show that one key factor is heat.
This might seem obvious, and we have
all experienced once in our life the con-
sequence of leaving our beloved CDs –
or cassettes for the most experienced of
us – under our car’s rear window on a
hot summer’s day…
What is far less known is the mathemat i-
cal relationship between expected life-
span and high temperature exposure.
Many studies have shown that for each
5°C increase, lifespan is halved! Sorry
about not converting into Fahrenheit -
the law doesn’t work out so easily.
Sometimes the metric system is not so
bad, especially when one wants to
launch a probe to Mars… But that’s an-
other story.
Back to our story. If a component life-
time is given for 10 years at 20°C, it will
only last one day if permanently exposed
to 80°C! This very same component will
last for 40 years if ambient temperature
is only 10°C…
This law does not take all parameters
into account, but it is close enough to
reality to rely on it when designing elec-
tronic circuits.
We see then that while it is very impor-
tant to chose components designed to
resist high temperatures, it is always
preferable to stop the problem at source,
by simply ensuring that components do
not overheat.
In continuous round the clock domestic
use – but is this still domestic use? –
provided you respect the location advice
mentioned in the Owner's manual, the
darTZeel NHB-108 model one stabilizes at
around 50°C on its heat sinks. As bipolar
transistors can work as high as 120°C,
the margin is comfortable here.
The internal temperature, on the mother
plate module, is around 40°C. At this
crucial place are installed the very ex-
pensive filtering capacitors. Do not be
worried too much: at 40°C, 24/24, their
estimated span life is… 40 years.
Just imagine: a poorer design – we will
not mention any name – subject to an
internal temperature of 60°C would im-
ply a change of capacitors every 2 and a
half years!