dbx Compression 101, Manual

Compression 101 - November 1998

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Hard knee/OverEasy®

The OverEasy® switch is used to switch between Hard and Soft knee compression styles.
When the compressor is set for Hardknee, the compression ratio applies only to signals
above the threshold level. If the compressor is set for Soft knee, the compression ratio
gradually increases from 1:1 to the current selected ratio over a range through the threshold
area, so that the transition from uncompressed to compressed is more gradual. the difference
between Hard Knee and OverEasy® is more obvious at high compression ratios. Once the
input signal crosses the Threshold, the unit will compress the signal at the full ratio level.

OverEasy® compression is useful when performing high-ratio compression or limiting on a
signal. When the compression gradually fades in, it doesn’t sound as obtrusive as when it
suddenly starts limiting the signal. If you’re looking for a “brick wall” limiter, the switch
should be set for Hard knee to stop any transients from slipping through without affecting
lower level signals. Lower Ratio levels may require a hard knee setting so that the
compression slope isn’t too narrow and you loose some of the compressive “punch.”

Common compressor settings

This section is meant to demonstrate some example compressor settings on various
instruments.These are merely suggested settings, but they can help you to get started if you
are new to compression or need help finding a particular sound.

Vocal Limiting

Vocalists tend to be one of the most dynamic recording challenges in any studio or stage.
Even though a singer may go from a whisper to a scream during the course of a song, it’s the
engineer’s job to keep the vocal’s level in line with the rest of the ensemble.You can do this
by setting the compressor with a high ratio and a high threshold. This way, softer sections
will go by uncompressed, and louder peaks will be kept under control.

Threshold set so that the loudest sections get around -6 of reduction (usually
around 3 o’clock)
Ratio set for 6:1
OverEasy® switch engaged
The Threshold should be set so that loud sections get compressed around 6dB and
quiet passages get no compression at all.

Vocal Compression and Spoken Word

In other cases, you may want to compress the entire dynamic range of a vocal.This is typical
of pop vocals and voiceovers for radio commercials.Whenever there is signal, there is some
compression taking place; just barely on the soft passages, and up to 12 dB of reduction
during loud passages.

Threshold set so that one GAIN REDUCTION LED (-1 dB) lights during the softest
passages with signal (usually around 11 o’clock)
Ratio set for 2:1
Attack set fairly fast (8-9 o’clock)
Release set between 10 and 12 o’clock
Raise output to compensate for gain reduction

Compression 101