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To Compress or Not to Compress…

Within the same second, singers may jump from a subtle, emotional phrase to a screaming-loud, needle-pegging, engineer torturing high note.

Some engineers use a lot of compression and limiting; other engineers don’t use any.

In commercial popular music, the use (and overuse) of dynamic processors is common, especially in the recording world.

Because commercial recordings use compressors on many of the mix ingredients and because the mastering process often overuses peak limiters, some use of compressors and limiters is almost necessary in order to achieve a polished sound.

Let’s Look What Compression Is:

Imagine yourself listening to the mix, and every time the vocal track starts to get too loud and read too hot on the meter, you turn the fader down and then back up again for the rest of the track.

That is exactly how a compressor works.

The compressor is an automatic volume control that turns loud parts of the musical signal down when they exceed a certain level (voltage).

The circuit that actually controls the level is the VCA (voltage controlled amplifier), the DCA (digitally controlled amplifier), or another externally controlled amplifier circuit.

Because an audio waveform is alternating current with changing amplitude over time, it is essentially voltage.

The amplitude can be used to trigger the amplifying circuit to adjust in direct correlation to the energy field.

The dramatic difference between a recording mix and a live mix is feedback.

If the live sound operator used the same amount of compression as the recording engineer, feedback would be extreme even in the best and most finely tuned system.

Compression on a Vocal Track

When used correctly, compression doesn’t detract for the life of the original sound – on fact, it can be the one tool that helps life and depth to be heard and understood in a mix.

Imagine a vocal track. Singers perform many nuances and licks that that define their individual style.

Within the same second, they may jump from a subtle, emotional phrase to a screaming-loud, needle-pegging, engineer torturing high note.

Even the best of us aren’t fast enough to catch all of these changes by simply riding the input fader.

In this situation, a compressor is needed to protect against excessive levels.

As the loudest parts of the source are turned down, we’re able to bring the overall level of the channel up.

In effect this brings the softer sounds up in relation to the louder sounds.

The subtle nuance becomes more noticeable so the individuality and style of the artists is more easily recognized, plus the understandability and audibility of the lyrics are greatly increased.

-Bill Gibson