Channel controls, 48v phantom power, Low cut – MACKIE ONYX 1640I User Manual
Page 14: U” like unity gain
14
Onyx 1640i
Channel Controls
The vertical channel strips look very similar, and have
only a few differences between them. Each
channel works independently, and just controls the
signals plugged into the inputs directly behind it.
“U” like Unity gain
Mackie mixers have a “U” symbol on almost every level
control. It stands for “unity gain,” meaning no change in
signal level. The labels on the 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.
22. 48V PHANTOM POWER
Most modern professional condenser mics require 48V
phantom power, which lets the mixer send
low-current DC voltage to the mic’s electronics through
the same wires that carry audio. (Semi-pro condenser
mics often have batteries to accomplish the same
thing.) “Phantom” owes its name to an ability to be
“unseen” by dynamic mics (Shure SM57/SM58, for
instance), which don’t need external power and aren’t
affected by it anyway.
Press this switch in if your microphone requires
phantom power. (Always check the position of this
switch before connecting microphones.) An LED lights
just above the button to indicate that phantom power is
active on that channel.
Never plug single-ended (unbalanced)
micro phones, or ribbon mics into the mic
input jacks if phantom power is on. Do not
plug instrument outputs into the mic XLR input jacks
with phantom power on, unless you know for certain it
is safe to do so. Be sure the main level [73] is turned
down when connecting microphones to the mic inputs
when phantom power is turned on, to prevent pops from
getting through to the speakers.
23. LOW CUT
All 16 channels have a low-cut switch (often referred
to as a high-pass fi lter) that 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 fi ltering 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 amplifi er power.
48V
48V
48V
48V
48V
SOLO
MUTE
SOLO
MUTE
SOLO
MUTE
SOLO
MUTE
SOLO
MUTE
EQ
EQ
EQ
EQ
EQ
SUB
ASSIGN
MAIN
MIX
1-2
3-4
GAIN
1
2
3
4
5
4
2
1
5
6
3
PAN
AUX
AUX
AUX
AUX
AUX
LINE
FW 1
LINE
FW 2
LINE
FW 5
LINE
FW 4
75Hz
18dB/OCT
75Hz
18dB/OCT
75Hz
18dB/OCT
LINE
FW 3
HIGH
12kHz
LOW
80Hz
U
+15
-15
U
+15
-15
U
+15
-15
U
+15
-15
8k
400
2k
2k
100
400
HIGH
MID
FREQ
LOW
MID
FREQ
+
40dB
U
-
20dB
U
20
30
40
60
L
R
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
SEND
PRE
POST
OL
+
10
0
-
20
SUB
ASSIGN
MAIN
MIX
1-2
3-4
GAIN
4
2
1
5
6
3
PAN
HIGH
12kHz
LOW
80Hz
U
+15
-15
U
+15
-15
U
+15
-15
U
+15
-15
8k
400
2k
2k
100
400
HIGH
MID
FREQ
LOW
MID
FREQ
+
40dB
U
-
20dB
U
20
30
40
60
L
R
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
SEND
PRE
POST
OL
+
10
0
-
20
SUB
ASSIGN
MAIN
MIX
1-2
3-4
GAIN
4
2
1
5
6
3
PAN
HIGH
12kHz
LOW
80Hz
U
+15
-15
U
+15
-15
U
+15
-15
U
+15
-15
8k
400
2k
2k
100
400
HIGH
MID
FREQ
LOW
MID
FREQ
+
40dB
U
-
20dB
U
20
30
40
60
L
R
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
SEND
PRE
POST
OL
+
10
0
-
20
SUB
ASSIGN
MAIN
MIX
1-2
3-4
GAIN
4
2
1
5
6
3
PAN
HIGH
12kHz
LOW
80Hz
U
+15
-15
U
+15
-15
U
+15
-15
U
+15
-15
8k
400
2k
2k
100
400
HIGH
MID
FREQ
LOW
MID
FREQ
+
40dB
U
-
20dB
U
20
30
40
60
L
R
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
SEND
PRE
POST
OL
+
10
0
-
20
SUB
ASSIGN
MAIN
MIX
1-2
3-4
GAIN
4
2
1
5
6
3
PAN
HIGH
12kHz
LOW
80Hz
U
+15
-15
U
+15
-15
U
+15
-15
U
+15
-15
8k
400
2k
2k
100
400
HIGH
MID
FREQ
LOW
MID
FREQ
+
40dB
U
-
20dB
U
20
30
40
60
L
R
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
MAX
O
O
SEND
PRE
POST
OL
+
10
0
-
20
2
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
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