Input Connection; Unbalanced Input Wiring; Balanced Input Wiring; Balanced And Unbalanced Phone Plug Wiring - Macro-Tech 24x6 Reference Manual

3.3.1 Input Connection

Both the balanced XLR and phone jack inputs have a
nominal impedance of 20 k ohms (10 k ohms with un-
balanced wiring) and will accept the line-level output of
most devices. Female XLR input connectors are pro-
vided on the standard P.I.P.-FX input module (other PIP
modules are described in Section 8.1). Correct input
wiring will depend on two factors: (1) whether the input
signals are balanced or unbalanced, and (2) whether
the signal source floats or has a ground reference. Fig-
ures 3.7 and 3.8 show the recommended connection
techniques for each type of signal source.
The amplifier's built-in ¼ inch input phone connectors
can be wired similarly for balanced or unbalanced, float-
ing or ground-referenced sources. The connectors have
Fig. 3.5 Unbalanced Input Wiring
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Fig. 3.6 Balanced Input Wiring
a standard tip-ring-sleeve (TRS) configuration: the tip is
positive (+), the ring is negative (–) and the sleeve is
ground (see Figure 3.7). Wiring for various sources fol-
lows the XLR wiring guidelines shown in Figures 3.5
and 3.6.
The phone jacks should not be used as inputs when a
PIP module with active circuitry is installed. The phone
jacks are in parallel with the output of the PIP module,
so an input signal connected to the phone jacks can
feed backwards into the active circuitry of the PIP and
cause undesirable distortion. You can use the phone
jacks for signal input with any of the following PIP mod-
ules installed: P.I.P.-FX, P.I.P.-BB, P.I.P.-FMX, P.I.P.-FXQ
and P.I.P.-FPX. All other PIP modules have active cir-
cuitry and should not be installed if you plan to connect
input signals to the phone jacks. The phone jacks can
always be used as "daisy chain" outputs to feed post-
processed signals from the PIP to the inputs of other
amplifiers.
Fig. 3.7 Balanced and Unbalanced Phone Plug Wiring
® 24x6 & 36x12 Power Amplifiers
Reference Manual