darTZeel Audio NHB-108 A version - Manual (Page 15)

darTZeel NHB-108 model one Owner's Manual Page 15 of 17
scribed in chapter 6.1. "Fuse(s) replace-
ment"
.
In order to avoid this situation, we rec-
ommend that you wait around 3 seconds
before powering you darTZeel NHB-108
model one ON again, when switched OFF.
7.2.9. RAS (Regular And Satisfactory)
In such a situation, we sadly deplore
having no real cure.
We suggest you display your most
charming smile, relax in your armchair,
and enjoy listening to your favorite
tunes.
Symptoms should disappear by them-
selves within a few days. If everything
continues OK, please invite some friends!
8. Version B
As we told you at the beginning of this
owner's manual, the darTZeel NHB-108
model one exists in 2 different versions
The version B has 2 added features
compared to version A, and these are:
XLR inputs are true floating balanced,
coupled via input transformers.
Output DC voltage drift is monitored and
zeroed by an analog, low phase shift cir-
cuit.
It is always possible to swap from ver-
sion A to version B at some later date.
This change uses exactly the same cir-
cuits and components, as if the machine
was directly purchased in version B.
Hence a modified version becomes a
fully-fledged version B, as shown by the
identification plate (1)
, newly engraved.
8.1. XLR floating inputs
Having in mind the wish to satisfy every
user, we specially developed true float-
ing balanced XLR inputs. Instead of us-
ing electronic circuitry having poor com-
mon mode rejection, the darTZeel NHB-
108 model one uses very high quality
transformers.
Thus, the Input Impedance Selector (Z
i
)
now has 3 positions instead of 2. This
third one, located at center position, is
needed to isolate the transformers from
the audio when XLR inputs are not used.
This selection is done by means of relays
of the highest quality available. The rear
panel labeling is thus in conformity with
the version B, which is the one that will
need the most of the interventions.
8.2. DC output voltage drift
To be fully independent from external
temperature changes, a new analog, real
time correction circuit has been added.
The darTZeel NHB-108 model one is now
able to work over a great temperature
range, without any significant DC voltage
drift.
This DC output voltage drift correction
circuit can be disabled if needed.
8.3. Version A versus B
Although the version B is more versatile
in use and significantly more expensive
than the version A, there is no subjective
sound improvement.
The use of relays, however high their
quality may be, for switching the XLR
inputs, constitutes an extra stage in the
signal path.
In addition, the circuit used for correct-
ing the DC output voltage drift, despite
all the care we put into it during its de-
sign, cannot be kept entirely outside the
signal path. This is why you can cut it
out if so desired.
It is interesting to note, however, that
when using the 50Ω BNC Zeel Inputs (6) in
conjunction with DC drift correction dis-
abled, the version B behaves sonically
exactly like the version A, and that the
50Ω mode is the one which offers the
highest quality available.
If you want to know more about this
topic… please read the Audiophile's tech-
nical manual!