darTZeel Audio NHB-18NS - Manual (Page 6)

darTZeel NHB-18NS
User Manual, version 0.93 Page 6 of 10
3.3. Connecting the NHB-18NS
First connect the external power supply’s umbilical
cord to the power connector located on the Rear
Panel (Chapter 3.2. fig 9).
Then connect the AC cord into your wall socket.
Phono input:
Use inputs I (Chapter 3.2. pos. 1). You can either
connect the ground wire to left or right channel.
The toggle switch allows choosing phono ground
path between signal ground, AC earth, or floating.
Default position is Gnd (right). If you hear some
abnormal rumble, you can play with both channels’
toggles in order to minimize it.
Phono settings: You can change the phono input
settings by a wide margin, allowing for most MM
and MC cartridges. This can be done using a solder
iron. This will be explained in details in the final
manual release. Factory settings are:
MC, gain = 60 dB, load = 836 ohms
This setting works well for most audiophile car-
tridges with an output level from 0.3 to 1 mV.
Line inputs:
Inputs II to V (Chapter 3.2. pos. 2 & 3) are for
RCA single ended sources, input VI is for XLR true
balanced sources.
Toggle switches:
For inputs II to V, default position is center. Left
position provides 6 dB of attenuation in the case
your source would exhibit a very high output level.
Right position is for Zeel 50-ohm purpose, dedi-
cated to future darTZeel sources.
For input VI (Chapter 3.2. pos. 4), the upper tog-
gle default position is center. Right position offers
600-ohm input impedance for professional gear.
Left position lowers the gain by 6 dB; this attenua-
tion only works when true floating source is used
(transformer output source).
Lower toggle switch allows for various ground path
schemes regarding the XLR chassis jack. Default
position is right. Center position is floating, useful
in certain circumstances for cancelling ground
loops. Left position is with XLR chassis connected
to ground via a 100-ohm resistor, for same purpose
as described for center position.
Outputs:
Nothing particular to notice here, save the following:
REC output (Chapter 3.2. pos. 8) is a fixed, buff-
ered output. Loading it with a matching component
like a recorder or a CD burner will therefore not
affect the sound quality. Due to non use of any
global negative feedback, the output gain is slightly
lower than 0 dB.
BNC darT outputs (Chapter 3.2. pos. 7): All these
3 output are separately buffered, and are dedicated
for feeding the darTZeel NHB-108 model one
power amplifier. Optional, built-in filters can be
activated for bi-amping or tri-amping purpose.
This special feature will be explained in details in
the final manual release.
3.4. Using the NHB-18NS
Once everything has been properly connected, you
can power the preamplifier ON by pressing the
Power Nose (Chapter 3.1. pos. 1).
After about 10 seconds, the NHB-18NS is ready to
play music.
When “enjoying” from a line source to another one,
about half a second dead-time is allowed for block-
ing bumps and clicks.
When “enjoying” from line to phono, a very small
click can be heard (independent of pleasure control
position), then the phono stage is activated after
around 8 seconds.
When going back from phono to line, only half a
second is required.
Balance control (Chapter 3.1. pos. 4):
This is not a standard balance control (of course, it
is a darTZeel machine)!
When using the Balance, the change only begins
after about plus and minus 5 degrees of rotation,
ensuring that when you are close to middle posi-
tion, balance channel is kept dead center.
At full right position, R channel is increased by 3.5
dB, L channel lowered by 3.5 dB.
At full Left position, L channel is increased by 3.5
dB, R channel lowered by 3.5 dB.
This feature allows for very fine adjustment, and
keeps global loudness at same level even while
altering the balance control from central position.