Low Cut; Aux 1, 2, 3, & 4; Pre - Mackie 1642VLZ4 Owner's Manual

34. Low Cut

The low cut switch (not present on channels 13-16),
often referred to as a high pass filter, cuts bass frequen-
cies below 75 Hz at a rate of 18 dB per octave. This ain't
no thrown-in dime-store filter — an 18 dB per octave
curve requires an elaborate circuit. Nothing but the best
for you.
We recommend that you use this on every sound
source except kick drum, bass guitar, or bassy synth
patches. These aside, there isn't much down there that
you want to hear, and filtering it out makes the low stuff
you do want much more crisp and tasty. Not only that,
but low cut can help reduce the possibility of feedback
in live situations, and it helps to conserve amplifier
power.
With low cut, you can safely boost low EQ. Many
times, bass shelving EQ can really benefit voices.
Trouble is, adding low EQ also boosts the subsonic
debris: Stage rumble, mic handling clunks, wind noise
and breath pops. Low cut removes all that debris so you
can boost the low EQ without blowing your subwoofers.
Here's a frequency curve of low EQ combined with
low cut:
+15
+10
+5
0
–5
–10
–15
20 100
Hz Hz
35. Aux 1, 2, 3, & 4
These four knobs tap a portion of each channel's
signal, mix them together and send them to the aux
send [6] outputs. They are off when turned fully down,
deliver unity gain at the center detent, and can provide
up to 15 dB of gain turned fully up. Chances are you'll
never need this extra gain, but it's nice to know it's
there if you do.
The aux send outputs are then patched to parallel
effects processor inputs or stage monitor amp inputs.
Aux sends 1 and 2 levels are controlled not only by the
channel's aux knobs, but also by the aux send [49]
master knobs.
1k 10k 20k
Hz Hz Hz
Aux sends can also be used to
generate separate mixes for recording
or "mix-minuses" for broadcast.
By using aux 1 or 2 in the pre [35]
mode, these mix levels can be obtained
independently of a channel's fader [25]
settings.
We recommend going into a
stereo reverb in mono and
returning in stereo. We have
found that on most "stereo" reverbs, the
second input just ties up an extra aux
send and adds nothing to the sound.
There are exceptions, so feel free to try
it both ways. Should you choose to use
two aux sends, use the "odd" aux (1 or
3) to feed its left input and the "even"
aux (2 or 4) to feed the right input.
Remember, if you're also dealing with
a stereo source signal, you'll want to
follow the sides — use the odd aux on
the channel carrying the left side and
the even aux on the channel carrying the right.

36. Pre

This switch determines the tap point of aux 1 and 2.
Generally, "post" sends are used to feed effects devices,
and "pre" sends are used to feed your stage monitors.
See the "Pre vs. Post" diagram below. Aux 3 and 4 are
always in post mode.
LOW
INPUT TRIM INSERT
CUT
'PRE' SIGNAL
In post mode (switch up), aux 1 and 2 will follow
the EQ [32], low cut [34], fader [25], and mute [30]
settings. If you fade the channel, you fade the send.
This is a must for effects sends, since you want
the levels of your "wet" signals to follow the level
of the "dry."
In pre mode (switch down), aux 1 and 2 follow the
gain and low cut settings only. EQ, pan, fader, and mute
settings have no effect on the pre sends. This is the
preferred method for setting up stage monitor feeds
— they'll be controlled independently of the fader and
mute moves.
MUTE
PAN ASSIGN
EQ
FADER
AUX 1
'POST' SIGNAL
PRE SWITCH
Owner's Manual
34
35
36
33
AUX 2
17