Mackie ProFX8 User Manual

Owner’

s Manual

In addition to a mix of the other channels, the USB 

output to your computer can contain any input from 
your computer, if this switch is down. (This switch only 
affects the output to your computer, not the headphones 
or main mix.) 

• 

If disengaged (out), the USB output to your 
computer will just be the main mix. This is a 
good position for overdubbing, as any playback 
from your computer can be played in your main 
speakers and headphones, while you play along 
with a guitar and record only the guitar via 
USB. This is also good for live recording, as a 
safeguard against feedback. Here, the USB level 
knob should also be down. 

• 

If pressed in, the USB output to your computer 
will be the main mix, including any audio 
coming in from your computer. This is a good 
position to record live performances where 
playback of audio from the computer is also 
part of the performance.

This controls the volume of the headphones output 

from off to maximum gain.

Warning: The headphone amplifi er is de-
signed to drive any standard headphones to a 
very loud level. It can cause permanent hear-

ing damage. Even intermediate levels may be painfully 
loud with some headphones. Be careful! Always start 
with the phones level control turned all the way down 
before connecting headphones or making any connec-
tions. Keep it down until you’ve put on the headphones, 
and turn it down fi rst whenever you play a new source or 
instrument.

This LED will light if the signal coming into the stereo 

return inputs [12] is too high, and this may cause dis-
tortion due to overloading.

The OL LED comes before the stereo return fader 

[45], so the fader has no effect in your efforts to turn off 
the OL LED.

Check your external processor or other device, and 

turn down its level until the OL LED does not come on.

Press this switch in to mute the signals coming into 

the stereo return inputs [12].

Use this fader to lovingly adjust the level of any audio 

coming into the stereo return inputs [12] from your 
external processors or other equipment. The audio is 
added to the main mix, and it can also be muted with 
the stereo return mute switch [44].

Typically, this fader can just live at the unity U mark, 

and the external device’s output control set at whatever 
they call unity gain (check the manual of the effects 
unit, CD player, drum machine, or whatever). If that 
turns out to be too loud or too quiet, adjust the external 
device’s outputs, not the mixer. That way, the mixer’s 
faders are easy to relocate at the unity U mark. The 
range is off to +10 dB.

Use this fader to gently adjust the level of the stereo 

output from the internal FX processor being added to 
the main mix. The range is off to +10 dB with unity at U.

This fader controls the overall level of  the monitor 

send signal sent out to your stage monitors.

Adjust it carefully, and check that your band are 

happy with the levels. The fader does not affect the 
main mix level. 

The monitor send signals are off with the fader fully 

down, the “U” marking is unity gain, and fully up pro-
vides 10 dB of additional gain. 

This fader controls the level of  the main mix, and 

affects the meters [34], and main line-level outputs 
[4, 15]. The level adjustment occurs after the stereo 
graphic EQ [37] in the signal path.

This gives you ultimate control over your audience. 

Adjust it carefully, with your good eye on the meters to 
check against overloading, and your good ear on the 
levels to make sure your audience is happy.

The control does not affect the monitor send [13], 

tape output [19], headphones [17], or USB output [5].

The main mix signals are off with the fader fully down, 

the “U” marking is unity gain, and fully up provides 10 
dB of additional gain. This additional gain will typically 
never be needed, but once again, it’s nice to know it’s 
there. The level control is stereo, as it affects both the 
left and right of the main mix equally. This is the control 
to turn down at the end of the song when you want “The 
Great Fade-Out.”