Mackie ProFX12v2 Manual Do Proprietário

Owner’

s Manual

there is more protection to your system from distortion 
and overload due to poor microphone technique (say 
it ain't so) and general pops, bangs and heavy metal 
screaming. The soft knee means that the compression 
slowly ramps up to 6:1 from the threshold. It does not 
jump abruptly to 6:1, as this would be hard knee  
compression, and harder on the ears too.

The graph on the previous page shows the input signal 

level going into the compressor, versus the output level  
coming out of it. It is the typical graph to view when  
compressors are discussed, and is just the kind of thing 
our engineers like to discuss during the company  
Christmas party

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If the compressor is off, then the input = output. For 

example an input signal level of +5 dBu results in an 
output level of +5 dBu. The diagonal line from lower left 
to upper right represents x = y, that is, input = output.

At the maximum compression, the threshold is  

set at  0 dBu, and the input to output relationship  
is represented by the lower curve. If the input is  
–5 dBu (that is, below the threshold), the output  
is –5 dBu. As the input reaches 0 dBu, the output  
is a bit less than 0 dBu. If the input is +5 dBu, the  
output is about +2 dBu. If the input reaches +10 dBu, 
then the output is +3 dBu. Notice the shapely curve  
of the soft knee between the diagonal slope of x = y   
and the compressor slope of 6:1 (the compression 
ratio). 

The other green curves represent in-between  

positions of the compressor knob, with higher  
thresholds before compression begins.

Outboard compressors often have controls such as 

compression ratio, threshold, soft knee/hard knee,  
attack time, and release time. These last two affect how 
quickly the compressor kicks in when the input exceeds 
the threshold, and how quickly it is released after it 
drops below the threshold. In this compressor, these 
parameters are specially chosen to give you the best 
overall performance.

Adjust the threshold carefully, so your dynamic range 

is still lovely, without distortion or overload during the 
performance. Run through a few practice screams and 
high-notes, and adjust the compression as required.

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The USB switch on the last stereo channel provides 

stereo playback of iTunes

®

, or a DAW via the USB    

connection. Like any other input, this signal may  
also be EQ'd, sent to an aux bus, or mixed in with  
the other signals and assigned to subgroups or main 
outs. This switch overrides the TRS inputs.