Unbalancing A Line - Mackie 1642VLZ4 Owner's Manual

Unbalanced RCA Connector
RCA-type plugs (also known as phono plugs)
and jacks are often used in home stereo and video
equipment and in many other applications. RCA plugs
are unbalanced. Connect the signal to the center post
and the ground (earth) or shield to the surrounding
"basket." Be sure the cables are wired per AES (Audio
Engineering Society) standards:
Unbalanced RCA Connector
Sleeve – Shield (Ground)
Tip – Positive (+ or hot)
Unbalanced RCA Connector

Unbalancing a Line

In most studio, stage and sound reinforcement situ-
ations, there is a combination of balanced and unbal-
anced 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 discon-
nected.
• In some cases, you will have to make up special
adapters to interconnect your equipment. For
example, you may need a balanced XLR female
connected to an unbalanced 1⁄4" TS phone
plug.
26
1642VLZ4
SLEEVE TIP SLEEVE TIP
TRS Send/Receive Insert Jacks
Single-jack inserts are 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 the illsutration below.
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 return from the unit to the
mixer is on the ring.
ring
(TRS plug)
tip sleeve
This plug connects to one of the
mixer's Channel Insert jacks.
Unbalanced 1/4" Insert Connectors
Special Connections
The balanced-to-unbalanced connection has been
anticipated in the wiring of 1642VLZ4 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. Conversely, a 1⁄4"
TRS plug inserted into a 1⁄4" unbalanced input will
automatically tie the ring (low or cold) to ground
(earth).
Using the Send Only on an Insert Jack
If you insert a TS (mono) 1⁄4" plug only partially (to
the first click) into a VLZ4 insert jack, the plug will not
activate the jack switch and will not open the insert
loop in the circuit (thereby allowing the channel signal
to continue on its merry way through the mixer).
This allows you to tap out the channel or bus signal
without interrupting normal operation.
If you push the 1⁄4" TS plug in to the second click,
you will open the jack switch and create a direct out,
which does interrupt the signal in that channel. See the
illustration on the next page.
SEND to processor
tip
ring
RETURN from processor