User guide

Engineer 418 & 818 User Manual Page 53
The big picture
Before attempting to configure the algorithm, let’s take a look at the main parameters that will come into play.
The figure above gives us an idea of the problem to solve and the tools at our disposal: The blue line
represents the input volume offered to the algorithm; the red line depicts the overall volume we would like as
the output volume.
The goal is to modify our input volume in a way it will be in between the orange lines marked “Tolerance” by
the time we’re done. The tolerance can be set as an offset to the desired target level. If our virtual sound
engineer has low tolerance, he’ll try to match the target level as accurately as he can: The higher the tolerance,
the more slack will be allowed in the source level.
But when to intervene? Sometimes the source level will only be outside of the target area for a short time. The
maximum amount of time this is allowed to happen is set by the reaction time. Setting this to a short period of
time will result in a nervous engineer, turning the knobs as soon as the volume deviates from the target we’ve
set: The longer the reaction time, the more “lazy” our engineer will become.
You might be thinking you’ll want to set the reaction time as short as possible to counter sudden peaks in the
volume, but there’s no need: Sudden peaks in the source volume are countered by three limiters (low-, mid-
and high tones). The purple line marked “headroom” shows us the maximum level at which these peaks are
allowed before these limiters kick in.
Finally, we need to account for situations in which no music is being played. A human engineer wouldn’t turn
up the level to 10 when there’s (almost) no input, so neither will ours. You can set the minimum level he’ll
work with; it’s called the threshold and marked in green in the figure above. If the input level’s below the
threshold, the engineer will sit back and relax: All knobs will be set to 0, leaving the source signal unchanged.
Now that we have an idea of what we’ll be configuring, let’s get started!