Mackie SR40.8 Owner's Manual page 73

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 appli-
cations (Figure D). They are unbalanced and
electrically identical to a
jack (See Figure C). Connect the signal to the
center post and the ground (earth) or shield
to the surrounding "basket."
SLEEVE
Figure D: RCA Plug
UNBALANCING A LINE
In most studio, stage and sound reinforce-
ment 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 equip-
ment. For example, you may need a balanced
XLR female connected to an unbalanced
TS phone plug.
ring
(TRS plug)
tip
sleeve
This plug connects to one of the
mixer's Channel Insert jacks.
Figure F
1 ⁄ " TS phone plug or
4
TIP SLEEVE TIP
1 ⁄ "
4
SEND to processor
"tip"
"ring"
RETURN from processor
SPECIAL MACKIE CONNECTIONS
The balanced-to-unbalanced connection has
been anticipated in the wiring of Mackie jacks.
A 1 ⁄ " TS plug inserted into a
4
input, for example, will automatically unbalance
the input and make all the right connections.
Conversely, a 1 ⁄ " TRS plug inserted into a
4
unbalanced input will automatically tie the ring
(low or cold) to ground (earth).
TRS Send/Receive Insert Jacks
Mackie's dual-jack inserts are balanced
TRS 1 ⁄ " jacks and will also accept TS (unbal-
4
anced) lines. The Send signal is normalled
to the Return jacks. If you insert a plug into
the Return jack, the Send signal is inter-
rupted (and replaced by the Return line's
signal).
Mackie's single-jack inserts (only appear as
HEADPHONES L-INSERT and R-INSERT
jacks on the SR40•8 or SR56•8) are the three-
conductor, TRS-type ⁄ " phone jacks. They are
1
4
unbalanced, but have both the mixer output
(send) and the mixer input (return) signals in
one connector (See Figure F).
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.
Using the Send Only on an Insert Jack
If you insert a TS (mono)
partially (to the first click) into a Mackie
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).
MONO PLUG
Direct out with no signal interruption to master.
Insert only to first "click."
MONO PLUG
Direct out with signal interruption to master.
Insert all the way in to the second "click."
STEREO
PLUG
For use as an effects loop.
(TIP = SEND to effect, RING = RETURN from effect.)
Figure E
1 ⁄ " TRS balanced
4
1 ⁄ "
4
1 ⁄ " plug only
4
Channel Insert jack
Channel Insert jack
Channel Insert jack
73