Instrument Switch (Ch.1-2); Gain (Ch.1-2); Hi Eq - Mackie 402VLZ4 Owner's Manual

6. Instrument Switch (Ch. 1–2)
When this switch is pressed in,
channel 1 or 2's line input can accept
direct instrument-level signals from guitars
or other instruments. They will be
impedance-matched to the line input,
without the need for a DI box.
When this switch is out, you can connect
line-level sources such as CD players, MP3
players, keyboards, drum machines and
more. You will need a DI box if connecting
instrument-level signals to the inputs of
channel 3 and 4.
Direct-In (DI) boxes are commonly
available from most music stores.
They provide signal and
impedance matching for the direct
connection of guitars and other instruments
to amplifiers and mixers. They convert
unbalanced instrument-level signals to a
balanced mic-level output. Normally, they
just look like a funny little box with a 1/4" TS
input at one end, and an XLR output at the
other. The good thing is that you do not need
them with the 402VLZ4.
7. Gain (Ch. 1–2)
channels 1 and 2. This allows signals from
the outside world to be adjusted to optimal
internal operating levels.
If the signal comes 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 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.
14
402VLZ4
If you haven't already,
please read the 'Getting
Started' section on page 5.
Gain adjusts the input
sensitivity of the mic and
line inputs connected to
"U" Like Unity Gain
VLZ4 mixers have a "U" symbol on almost
every level control. This "U" stands for "unity
gain," meaning no change in signal level.
Once you have adjusted the input signal
to line-level, you can set every control at
"U" and your signals will travel through the
mixer at optimal levels. What's more, all the
labels on our level controls are measured
in decibels (dB), so you'll know what you're
doing level-wise if you choose to change a
control's settings.
2-Band Equalization
The 402VLZ4 has 2-band equalization at
carefully selected points — low shelving at
80 Hz, and hi shelving at 12 kHz. "Shelving"
means that the circuitry boosts or cuts all
frequencies past the specified frequency.
For example, rotating the low EQ knob 15 dB
to the right boosts bass starting at 80 Hz and
continuing down to the lowest note you
never heard.
With EQ, you can also screw things
up royally. We've designed a lot of
boost and cut into each equalizer
circuit, because we know everyone will
occasionally need that. But if you max the
EQs on every channel, you'll get mix mush.
Equalize subtly and use the left sides of the
knobs (cut), as well as the right (boost).
Very few gold-record-album engineers ever
use more than about 3 dB of EQ. If you need
more than that, there's usually a better way
to get it, such as placing a mic differently
(or using a different kind of mic entirely).

8. Hi EQ

This control
+15
gives you up to
+10
15 dB boost or
+5
0
cut above 12 kHz,
–5
and it is also flat
–10
at the center. Use
–15
20
it to add sizzle
Hi EQ
to cymbals, and
an overall sense of transparency, or edge to
keyboards, vocals, guitar and bacon frying.
Turn it down a little to reduce sibilance,
or to hide tape hiss.
100 1k 10k 20k
Hz Hz Hz Hz Hz