SECRETS OF COMPRESSION, PT. 1 BY RICH TOZZOLI
In this first installment in a two-part series, we’ll take a
look at compression as it applies
specifically to us guitarists. For
starters, we’ll talk about using
compression in the studio and
how you can apply it to your
tracks during mixdown. Next
month, we’ll examine the differences between compression
pedals you’d typically use in the
recording prodcess and plug-ins or hardware you’d use after
you’ve finished tracking.
Briefly, compression is about
controlling the dynamic range
of your instrument. A compressor reduces your volume using
a set of controls that vary with
each type of device.
With your typical studio-based hardware unit or
software plug-in, the main
controls are Threshold and
Ratio. When audio peaks rise
above your chosen Threshold
setting, they are reduced.
Anything under the Threshold
setting is not reduced or
affected. Ratio determines
the amount of gain reduction
that happens after the audio
rises above the Threshold setting. For example, a typical
3: 1 Ratio setting means that,
if the audio rises 3 dB above
the Threshold setting, the
compressor will hold that level
LEFT: A screenshot of the Sonnox Oxford plug-in. RIGHT: The control set on a Waves API 2500 plug-in.
how quickly it lets go of your
signal. Makeup Gain lets
you raise the overall output
level after you’ve compressed
the audio, thus maintaining
a robust signal even though
you’ve reduced its peaks.
With electric guitar, compression is not always necessary—especially when mixing
heavily distorted parts. For
example, when recording with
distorted tube amps, you’ve
already got a lot of compression
built into the sound (courtesy
of the power tubes), and compressing the signal further in
the mix may make it mushy or
washy. In that situation, I may
compress very lightly—perhaps
using a 2: 1 or 3: 1 ratio—and
then apply makeup gain to add
There is no right or wrong way to apply
compression. Whatever sounds right, is right.
to only 1 dB above the threshold, thus reducing the peak by
2 dB. Very high compression
ratios yield an effect called
limiting, which we’ll explore
in further columns.
The other set of adjustable
controls found in most com-
pressors are Attack, Release,
and Makeup Gain. Attack
determines how fast or slow
the actual compression takes
place, and Release governs
some volume. Even that may
not be required: My old Gibson
amps sound compressed right
at the speaker, so I tend not to
compress guitar parts recorded
on them.
RICH TOZZOLI is a
Grammy-nominated engineer and mixer who has
worked with artists ranging
from Al Di Meola to David
Bowie. A life-long guitarist,
he’s also the author of Pro
Tools Surround Sound Mixing and composes for the likes of Fox NFL, Discovery
Channel, Nickelodeon, and HBO.
