Low Cut (Channels 1-4); Gain (Channels 1-4); Stereo Line Ins; Imaginary Control - Mackie 1202VLZ4 Owner's Manual

3. Low Cut (Channels 1–4)
Each low cut switch, often referred to as a high pass
filter (all depends on how you look at it), cuts bass
frequencies below 75 Hz at a rate of 18 dB per octave.
We recommend that you use low-cut on every
microphone application 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.
Another way to consider low-cut's function
is that it actually adds flexibility during live
performances. With the addition of low-cut,
you can safely use low equalization on vocals.
Many times, bass shelving EQ can really benefit
voices. Trouble is, adding low EQ also boosts stage
rumble, mic handling clunks and breath pops.
Applying low-cut removes all those problems, so
you can add low EQ without blowing your subwoofers.
Here's what the combination of low EQ and low-cut
looks like in terms of frequency curves:
+15
+10
+5
0
–5
–10
–15
20 100 1k 10k 20k
Hz Hz Hz Hz
Low Cut
4. Gain (Channels 1–4)
If you haven't already, please read the level-setting
procedure on page 5.
Gain adjusts the input sensitivity of
the mic and line inputs connected
to channels 1 through 4. This allows
signals from the outside world to be
adjusted to optimal internal operating
levels.
If the signal originates through the XLR jack, there
will be 0 dB of gain with the knob fully down, ramping to
60 dB of gain fully up.
Through the 1⁄4" input, there is 20 dB of attenuation
fully down and 40 dB of gain fully up, with a "U" (unity
gain) mark at 10:00. This 20 dB of attenuation can be
very handy when you are inserting a very hot signal, or
when you want to add a lot of EQ gain, or both. Without
this "virtual pad," this scenario might lead to channel
clipping.
+15
+10
+5
0
–5
–10
–15
20 100 1k 10k
Hz
Hz Hz Hz Hz
Low Cut with Low EQ

5. Stereo Line Ins

(Channels 5–6, 7–8, 9–10 And 11–12)
These fully balanced inputs are designed for stereo
or mono, balanced or unbalanced signals, from –10 dBV
to +4 dBu. They can be used with just about any
professional or semi-pro instrument, effect or CD player.
In the stereo audio world, an odd-numbered
channel usually receives the "left signal." For example,
you would feed the 1202VLZ4's line inputs 5-6 a stereo
signal by inserting the device's left output plug into
the channel 5 jack, and its right output plug into the
channel 6 jack.
When connecting a mono device (just one cord),
always use the left (mono) input (jacks 5, 7, 9 or 11)
and plug nothing into the right input (jacks 6, 8, 10 or
12)— this way the signal will appear on both sides. This
trick is called "jack normalling."

6. Imaginary Control

This control is purely a figment of our imagination. It
will come in handy after long hours of mixing, when you
really would like a nice cup of tea, a vacation in Hawaii,
or a trip to the outer reaches of the Solar System. This is
the control for you. Be thankful you bought a 1202VLZ4.
We love you, man!

Effects: Serial Or Parallel?

The next two sections toss the terms "serial" and
"parallel" around like hacky sacks. Here's what we mean
by them:
20k
Hz
"Serial" means that the entire signal is routed through
the effects device. Examples: compressor/limiters,
graphic equalizers. Line-level sources can be patched
through a serial effects device before or after the mixer,
or preferably through the insert jacks located on the
rear panel (channel insert [17] send/return).
Insert
Send
Signal Processor
(e.g., Compressor)
Dry Signal
"Parallel" means that a portion of the signal in the
mixer is tapped off to the device (aux send), processed
Aux
Send
Insert
and returned to the mixer (stereo return) to be mixed
Send
Signal Processor
with the original "dry" signal. This way, multiple
(e.g., Reverb)
Signal Processor
(e.g., Compressor)
Dry Signal
channels can all make use of the same effects device.
Examples: reverb, digital delay.
Channel Path
Dry Signal(s)
Aux
Send
Signal Processor
Channel Path
Dry Signal(s)
Insert
Return
Aux Output
Return Section
Insert
Return
Wet Signal
Stage
Dry Signal(s)
Aux
Return
(e.g., Reverb)
Wet Signal
Dry Signal(s)
Owner's Manual
Processed
Signal
Processed
Signal
Mix Processed
Signal
Output
Section
Mix Processed
Stage Signal
9