33
SPECIAL MACKIE CONNECTIONS
The balanced-to-unbalanced connection has
been anticipated in the wiring of Mackie jacks.
A
1
⁄
4
" TS plug inserted into a
1
⁄
4
" TRS balanced
input, for example, will automatically unbalance
the input and make all the right connections. Con-
versely, a
1
⁄
4
" TRS plug inserted into a
1
⁄
4
"
unbalanced input will automatically tie the ring
(low or cold) to ground (earth).
TRS Send/Receive Insert Jacks
Mackie’s single-jack inserts are the three-
conductor, TRS-type
1
⁄
4
" phone. They are
unbalanced, but have both the mixer output
(send) and the mixer input (return) signals in
one connector (See Figure E).
The sleeve is the common ground (earth) for
both signals. The send from the mixer to the
external unit is carried on the tip, and the re-
turn from the unit to the mixer is on the ring.
RCA PLUGS AND JACKS
RCA-type plugs (also known as phono plugs)
and jacks are often used in home stereo and video
equipment and in many other applications (Fig-
ure D). They are unbalanced and electrically
identical to a
1
⁄
4
" TS phone plug or jack (See Fig-
ure C). Connect the signal to the center post and
the ground (earth) or shield to the surrounding
“basket.”
“tip”
This plug connects to one of the
mixer’s Channel Insert jacks.
“ring”
tip
ring
sleeve
SEND to processor
RETURN from processor
(TRS plug)
Figure E: Insert Plug
TIPSLEEVETIPSLEEVE
UNBALANCING A LINE
In most studio, stage and sound reinforcement
situations, there is a combination of balanced and
unbalanced inputs and outputs on the various
pieces of equipment. This usually will not be a
problem in making connections.
• When connecting a balanced output to an
unbalanced input, be sure the signal high
(hot) connections are wired to each other,
and that the balanced signal low (cold)
goes to the ground (earth) connection at
the unbalanced input. In most cases, the
balanced ground (earth) will also be
connected to the ground (earth) at the
unbalanced input. If there are ground-loop
problems, this connection may be left
disconnected at the balanced end.
• When connecting an unbalanced output to
a balanced input, be sure that the signal
high (hot) connections are wired to each
other. The unbalanced ground (earth)
connection should be wired to the low
(cold) and the ground (earth) connections
of the balanced input. If there are ground-
loop problems, try connecting the unbalanced
ground (earth) connection only to the input
low (cold) connection, and leaving the input
ground (earth) connection disconnected.
In some cases, you will have to make up special
adapters to interconnect your equipment. For ex-
ample, you may need a balanced XLR female
connected to an unbalanced
1
⁄
4
" TS phone plug.
Figure D: RCA Plug
