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any kind of twisted pair cable will be adequate.
The TDcontroller is intended to be used with symmetrical (balanced) sources (for instance a mixer) and
symmetrical loads (for instance a power amplifier (see figure). You can see that the TDcontroller provides
a low impedance path between pin 1 of its XLR connectors and its chassis. The TDcontroller can sustain
high current in pin 1 without degradation of output noise. We recommend that the sources and loads you
use have the same desirable characteristics.
It is sometimes claimed that connecting cable shield at both ends creates ground loops, and that the
current flowing in such loops will produce noise. This is not the case for most professional audio
equipment. In short, there are two kinds of loops in which voltages are present: the loops formed by
signal wires, and the loops formed by grounded conductors, among which are protective earth
conductors (PE) and signal cable shields.
When a cable shield is grounded at both ends, a loop is closed, and the resulting current causes a
reduction of the voltage induced on signal lines. This effect is what the cable shield is intended to
produce, since this is how it protects your signal from magnetic fields.
If
you
are
(unbalanced) source, it is best to use a
shielded twisted pair and to connect wire 3
of the cable to the shield at the source
output end (see figure). This technique
prevents noise currents flowing on the
return path of the signal. If you are using
an
amplifier
(unbalanced) input, it is best to use a
shielded twisted pair, and to connect wire 3
at the TDcontroller end only, as shown in
Fig. 2. This keeps a good capacitance
balance for the signal, however noise
currents flow on the return path of the
signal. (Note that this is only acceptable for
a short cable).
If you are using a symmetrical (balanced) source or amplifier which is prone to become noisy when a
current of less than 100 mA at the mains frequency (50 Hz or 60 Hz) is sourced into pin 1 of its XLR
connectors, you might consider opening the ground loops.
PS SERIES MANUAL REV3 10/10/05
ANALOGUE TDCONTROLLER SETTING-UP ADVICE
using
an
asymmetrical
with
an
asymmetrical
Mixing Desk
0V
Low Z ?
-
+
1
3
2
?
1
3
2
-
+
Low Z
TDcontroller
IN
Amplifier
-
+
1
3
2
PE
Safety
PE
1
3
2
Ground
-
+
Low Z
OUT
P.17
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