The audio compressor is an important device in an audio production setup. It is
very necessary as a tool to create a leveling between the loudest part and the
lowest part. It reduces the effect of dynamism or varying volume of a recording.
This is achieved by forcing waveforms to fit what is called an even mix. It can be
said to create a balance in a mix. It can be applied per input channel and can
also be applied to the overall mix depending on the result expected.
There are many component units or controls that jointly achieve this task in the
compression system.
As the name sounds, the unit controls the level of sound or signal that comes into
the compression unit.
THRESHOLD
The threshold is the major and foremost knob on the compressor. Its regulated
value can decide the fate of the other knobs on the system. For instance, if tuned
to zero, it terminates or makes the effect of the other knobs not to be felt. The
settings on the threshold determine the value at which compression takes place
on a signal and at this point, the dynamics of the recording starts changing.
Over time, on the job experience have proved that basically in an audio set up,
the most likely expectation for a natural compression should be between -3db to
-5db. This can serve as a good start point or preset but may be exceeded as
situation varies.
Also, it is important to know that, signals below the level of compression (threshold
value) will not be affected or compressed. They have to exceed that level.
The ratio can be seen as a partner to the threshold because of its relevance in
regulating the threshold response. It determines how hard or soft the compression
will be experience if the signal exceeds the threshold value.
For instance,
1:1 means that the signal experiences no turn down when it crosses the threshold.
2:1 means that for every value in (db) of a signal that crosses the threshold, the
compressor cuts it to half of the original value. In a case where the signal goes
above the threshold by 8db, the compressor slashes it to 4db over the threshold.
The ratio decides the intensity of the compression.
The attack and release is another knob to vary and get a very good output in a
compressor. Its effect can be experienced on instruments like the drum and the
guitar. The attack can fine-tune the sound of a kick and also sustain a snare drum a
bit longer. It can also create surround on the tone of a bass guitar.
The attack determines how quickly the filter reacts to changes in audio level while
the release defines how slowly the filter lets go of the change it made in the audio
level. The higher the value, the faster the attack, the faster the compression and
the faster the release, the faster it lets go of the audio signal. The attack and
release effect is well experienced when the threshold and ratio level is strong.
The expander also called noise gate is used to level sound under the specified
threshold as close to silence as possible. Expanders deal with the quiet part of the
signal while compression deals with the loud part.
The peak limiter allows signals below the specified input level to pass unaltered
while lowering the peaks of stronger signals that exceed this threshold. It is under
range dynamic processing. Signals that are not limited can attain a level called
clip. They are really used as a safety guard on setup to avoid damage on output
devices like speakers and also for amplifiers.
N/B: A good understanding of these controls and settings will go a long way in improving your mix.
That will be all for now and I believe you have learned something today about compressors. We can use the knowledge of what we've learned today to actually enhance our sounds and our mixes.
like always flee free to send in your questions and suggestion through comments and I will do my best to look into it.
Thanks for reading!
