18
ProFX8 and ProFX12
ProFX8 and ProFX12

For hybrid channels (mic input and

stereo line input), the gain control just

affects the microphone input.

For stereo channels (no mic input) the

gain control just affects the line-level

inputs, with 20 dB of gain, and 20 dB of

attenuation. There is no level set LED.

21. LEVEL SET LED

These LEDs are used with the gain control [20] to set

the channel preamplifi er gain just right for each source.

If you hear distortion on one or more of your channels,

check the level set LEDs are not on continuously, and

turn down the gain if they are.

22. LOW CUT

Each channel with a mic input has a low cut switch

that cuts the bass frequencies below 100 Hz, at a rate

of 18 dB per octave. All mic inputs are affected, and the

line inputs of the mono channels.

We recommend that you use low cut on every micro-

phone application except kick drum, bass guitar, and

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, low cut can help reduce the possibility

of feedback in live situations and help to conserve the

amplifi er power.

20. GAIN

If you haven’t already, please read the gain-setting

procedure on page 3. The gain adjustment allows all

your various source signals from the outside world to be

adjusted to the same optimal internal operating levels.

Setting the gain correctly will ensure that the pre-

amplifi er’s gain is not too high, where distortion could

occur, and not too low, where your quieter, exquisitely-

delicate passages might be lost in background noise.

For mono channels (mic input with a

mono line input), the gain knob adjusts

the input sensitivity of the mic and line

inputs.

Adjust the gain control so the level set LEDs [21]

come on occasionally during the louder moments of your

playing or singing, and go off when you stop.

If the signal comes through the mic XLR jack, there

will be 0 dB of gain (U for unity) with the knob fully

down, ramping to 50 dB of gain fully up.

Through the 1⁄4" mono input, there is 20 dB of

attenuation fully down and 30 dB of gain fully up,

with a “U” (unity gain) mark at 12:00. This 20 dB of

attenuation can be very handy when you are inserting

a very hot signal, need to add a lot of EQ boost, or both.

Without this “virtual pad,” this scenario might lead to

channel clipping.

MID
2.5kHz
MID
2.5kHz
MID
2.5kHz
MID
2.5kHz
MID
2.5kHz
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
RL
LOW CUT
100 Hz
U
GAIN
M
I
C
G
A
I
N
U+50
-20dB +30dB
4
12kHz
HI
MID
2.5kHz
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
12kHz
HI
MID
2.5kHz
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
12kHz
HI
MID
2.5kHz
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
12kHz
HI
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
RL
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
RL
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
RL
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
RL
LOW CUT
100 Hz
12kHz
HI
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
RL
LOW CUT
100 Hz
GAIN
7/85/6
12kHz
HI
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
RL
M
I
C
G
A
I
N
U+50
GAIN
M
I
C
G
A
I
N
U+50
9/10
12kHz
HI
LEVEL
SET
LEVEL
SET
LEVEL
SET
LOW CUT
100 Hz
U
GAIN
M
I
C
G
A
I
N
U+50
-20dB +30dB
LEVEL
SET
LEVEL
SET
LEVEL
SET
LOW CUT
100 Hz
U
GAIN
M
I
C
G
A
I
N
U+50
-20dB +30dB
LOW CUT
100 Hz
U
GAIN
M
I
C
G
A
I
N
U+50
-20dB +30dB
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
GAIN
80Hz
LOW
U
+15-15
U
+15-15
U
+15-15
U
+20-20
GAIN
U
+20-20
RL
11/12
EQEQEQEQ EQ EQ EQ EQ
12kHz
HI
PAN
AUX
U
+15
OO
MON
FX
U
+15
OO
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
dB
30
20
10
10
OO
40
50
5
5
U
60
321
OL OL OL OL OL OL OL OL
MUTE MUTE MUTE MUTE MUTE MUTE MUTE MUTE20 212223242526272829 3031
GAIN
U
+20-20
GAIN
MIC
GAINU+50LEVELSETLEVELSET
U
GAIN
MIC
GAINU+50-20dB +30dB