In The Studio
Back from the concert tour now and the band want you
to mix their new album (wow, you really made a good
impression on them, didn't you?). The first song is
a heavy rock, funk, electronica dance track (this
is an experimental band) that the record company want
to release as their first single. On listening to
the drum tracks you notice there's a lot of spill
on the individual tracks - the kick track has picked
up the snare, the snare track has picked up the hi-hat
etc. This will mean that any processing on those instruments
will be difficult, if not impossible. Let's start
with the kick track.
In the above waveform display
we can see the loud kick drum hits as large peaks
and the quiet snare hits as small peaks. If we were
to apply compression to this track, a common practice
on kick drum, then the snare hits would become louder.
This will cause problems when we want to mix down.
So by applying a noise gate to the kick drum track
in the same manner that we used in the live example,
we can eliminate the snare hits completely resulting
in a clean kick drum track that can be further processed.
Now let's look at the snare track.
Here we can see that in between
the actual snare hits (the large peaks) there are
a lot of other sounds. These comprise of toms, hi-hats
and other cymbal hits. Again, if we were to apply
compression to this track, all those other sounds
would become louder. But this snare part also contains
some ghost hits (quiet snare hits) that we want
to keep so if we just applied a noise gate to the
whole track, those ghost snare hits would be lost
This is where we need to apply frequency conscious
gating and this is how it's done.
Route the snare track to a sub group and insert
the noise gate on that group.
2. Also, send the original snare track's signal
into the side chain input of the noise gate.
3. Then listen to the side chain input monitor
- usually selected with a button on the gate
itself - and bring down the low pass filter
until the high frequency cymbals cannot be
heard. What you should be hearing now is a
rather dull sounding snare.
4. Then turn off the side chain monitor and
adjust the threshold until you can only hear
the snare, ghost notes too.
This won't completely clean
up the snare track, some tom hits will still sneak
through for example, but it will probably clean
90% of it.
Below is a snapshot of the audio mixer in Logic,
which shows the settings I used on the gate for
this example. Notice the high and low pass filter
settings; the gate is being triggered with audio
from the snare track between the range of 610Hz
to 830Hz thereby ensuring that high frequency cymbals
or low frequency toms won't trigger the gate.
Cleaning up recorded tracks in
this manner is quite common practice in studios.
Again, it's usually applied to acoustic instruments
but unlike live applications it can also be applied
to recorded vocal tracks (see the first example
in paragraph 3). However, I do not recommended that
noise gates are used during the actual recording
process for one simple reason - if the threshold
is not correct then you won't capture all of the
performance. It's better to get everything down
on tape, warts 'n' all, and then apply gating afterwards.