darTZeel Audio NHB-108 B version - Manual (Page 32)

darTZeel NHB-108 model one
User Manual, version B 1.0 Page 32 of 35
By switching the secondary windings accordingly,
the power transfer is optimized and the power tran-
sistors in the output stage remain within their safe
working range.
So we can only use one single output transistor pair
per channel. The signal path is shorter, uniform,
and only passes though one silicon junction at a
time.
Music is thus reproduced with unprecedented ease,
purity and fidelity, simply impossible with more
complex designs.
T7.3. Received idea
This chapter devoted to power supplies would not
be complete without the following little addition,
small in size but of great significance…
It is usually admitted in the audio world, particu-
larly in the high-end manufacturers' community,
that output current availability is of paramount im-
portance, to the point where one praises machines
capable of outputting dozens, or even hundreds, of
amperes.
What nonsense!
Until the contrary is proven, as far as we know
voltage and current are in a certain relationship, as
clearly stated by Ohm's law:
I R V
• =
R
V
I
=
I
V
R
=
It is of course the same equation, just written in its
3 most usual forms.
Now, let us take an ideal amplifier, capable of de-
livering exactly 250 watts/8
Ω, 500 watts/4Ω, 1000
watts/2 Ω, and a whopping 2000 watts/1Ω.
The currents needed to deliver these abundant and
generous powers are, respectively, of 5.6A, 11.2A,
22.4A and 44.8A.
Yes, we have to admit that the last figure is quite
high… So, this amplifier can deliver roughly 45
amps under 1
Ω.
Now say that you own speakers having an imped-
ance of 6
Ω, much easier to drive than 1Ω. How
many amperes will this imposing amplifier deliver
to your loudspeakers? 45 amperes with a big smile?
Not at all!
Given Mr. Ohm's law, the amplifier will deliver at
its best 333 watts, say 7.45A under 44.7volts.
So you can see that in the real world, you just need
7.5 amperes, not 45. Let us confess that for 333(!)
watts, this is quite reasonable…
Do you now better understand why "Lots of Am-
peres" does not necessarily mean "Superb Bass"?
T8. The sound of darTZeel
It is always hard to define objectively what we per-
ceive subjectively, isn't it? How to enjoy an excel-
lent glass of wine, if not sharing it with friends?
We could say that the darTZeel NHB-108 model
one
offers an outstanding temporal linearity, allow-
ing true three-dimensional re-creation.
We also could say that the bass is deeper than the
Mariana Trench, with every nuance incredibly ren-
dered.
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 NHB-108 model one, and you
know better than anyone what we are talking about.
So why do we need to produce any further advertis-
ing? In fact, just for the fun of it. And music is fun
too, isn't it?
T9. Reliability
T9.1. 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 "Re-
liability"? 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 interesting to ask
ourselves what are the most influential parameters
affecting the life span of a given component. Sev-
eral studies show that one key factor is heat.
This might seem obvious, and we have all experi-
enced once in our life the consequence of leaving
our beloved CDs – or cassettes for the most experi-
enced of us – under our car’s rear window on a hot
summer’s day…