Line Inputs; Gain; Insert - Mackie 1642-VLZ3 Owner's Manual

Unless you know for certain it is safe to do
so, never plug single-ended (unbalanced)
microphones, instruments, ribbon mics, or
electronic devices into the MIC [1] input jacks if the
phantom power is on.

2. LINE INPUTS

These 1/4" jacks share circuitry (but not phantom
power) with the mic preamps. You can use these inputs
for virtually any signal you'll come across, from instru-
ment levels as low as –50 dB to operating levels of –10
dBV to +4 dBu, as there is 45 dB of gain available via the
GAIN [3] knob. Note that channels 1-8 line inputs are
intially attenuated by 15 dB.
Always be sure to perform the Level-Setting Proce-
dure (page 3) when you connect a new input.
To learn how signals are routed from these inputs,
see the details lovingly described in the Channel Strip
section.
To connect balanced lines to these inputs, use a 1/4"
tip-ring-sleeve (TRS) plug, the type found on some
stereo headphones:
Tip = positive (+ or hot)
Ring = negative (– or cold)
Sleeve = shield or ground
To connect unbalanced lines to these inputs, use a
1/4" mono (TS) phone plug or standard instrument
cable:
Tip = signal (+)
Sleeve = ground

3. GAIN

These controls are not in the patchbay, but
they are the top row of knobs in the channel
3
strip section. (They are so vitally linked with
the inputs, this seemed like a good place to
describe them.)
Every time you plug something into a
MIC [1] or LINE [2] input jack, you should
perform the Level-Setting Procedure, and that
procedure is basically "how to use the GAIN
knob."
GAIN adjusts the input sensitivity of the
MIC and LINE inputs. This allows signals
from the outside world to be adjusted to
optimal internal operating levels.
Through the XLR jack (MIC), 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 (LINE), there
is 15 dB of attenuation fully down and 45
dB of gain fully up, with unity gain (U) at 10:00.
This 15 dB of attenuation can be very handy when you
are inserting a signal that is very hot, or you want to add
a lot of EQ gain, or both. Without this "virtual pad," a
scenario like this might lead to channel clipping.
The GAIN controls for stereo channels 9-10 and 11-12
are only used to adjust the Mic inputs. The line inputs
are set to unity gain.
The GAIN controls for channels 13-14 and 15-16 only
adjust the line-level inputs, as they have no Mic inputs.

4. INSERT

Found only on channels 1–8, these 1/4" unbalanced
jacks are for connecting serial effects processors such
as compressors, equalizers, de-essers, or filters. The
insert point is after the GAIN [3] control, but before the
channel's EQ [32], LOW CUT [34], FADER [25] and
MUTE [30] controls.
Insert cables must be wired thusly:
ring
(TRS plug)
tip sleeve
This plug connects to one of the
mixer's Channel Insert jacks.
Tip = send (to effects device input)
Ring = return (from effects device output)
Sleeve = common ground
Even though channels 1–8 already have DIRECT OUT
[5] jacks, INSERT jacks can also be used as channel
direct outputs (as they are post-GAIN, pre-EQ, pre-LOW
CUT, pre-FADER, and pre-MUTE).
Appendix B, page 27 has a lovely diagram (Figure F)
showing three ways you can use the INSERT jacks.
SEND to processor
"tip"
"ring"
RETURN from processor
Owner's Manual
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