Mackie ProFX12 Owner's Manual page 28

TRS Send/Receive Insert Jacks
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 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.
Figure E
Using the Send only on an Insert Jack
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.
will open the jack switch and create a direct out, which
does interrupt the signal in that channel. See Figure F.
NOTE: Do not overload or short-circuit the signal you
are tapping from the mixer. That will affect the internal
signal.
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."
For use as an effects loop.
(TIP = SEND to effect, RING = RETURN from effect.)
Figure F
28
ProFX8 and ProFX12
SEND to processor
"tip"
"ring"
RETURN from processor
Channel Insert jack
Channel Insert jack
STEREO
PLUG
Channel Insert jack
Mackie Stereo Inputs and Returns: Mono,
Stereo, Whatever
Stereo line inputs and stereo returns are a fine
The inputs and returns will automatically be mono or
how it works:
A mono signal should be patched into the input or
return jack labeled left (mono). The signal will be
routed to both the left and right sides of the return
circuit, and will show up in the center of the stereo pair
of buses it's assigned to, or it can be "panned" with the
pan control.
A stereo signal, having two plugs, should be patched
into the left (mono) and the right input or return jacks.
A jack switch in the right jack will disable the mono
function, and the signals will show up in stereo.
A mono signal connected to the right jack will show
up in the right bus only. You probably will only want to
use this sophisticated effect for special occasions.