Compression can make or break a vocal recording. Apply too much, and you'll destroy the performance and character. Apply too little, and you could have a hard time producing a track that sounds professional and ready for commercial release.
In the following guide, we'll help you understand precisely what compression actually does so you'll know how to compress vocals like a pro.
When recording vocals, it's important to ensure we can hear every word in the performance, and it's also essential the vocal sits comfortably in the mix. Depending on the style of music and the singer's performance, applying different amounts of compression will almost invariably improve the result.
The skill lies in understanding how compression works and how to apply it appropriately.
What Does a Compressor Do?
Compressors reduce the dynamic range of your signal; they make the louder and quieter parts of the performance closer to each other in level.
Vocals, by nature, are very dynamic and usually benefit from a little, or sometimes a lot of control, depending on the nature of the performance.
Aside from the main task of controlling dynamic range, a compressor changes the transients (in vocals, we call these the consonant sounds). Depending on the type of compressor circuit or plugin used, it can also colour the sound in a characterful way.
What Does Compression do to Vocals Specifically?
When used correctly, compression can make vocals sound more consistent and clear. Imagine a vocal performance with some parts that are very loud and others that are very quiet. Compression helps to even out these differences, making the loud parts softer and the quiet parts louder, so everything is more balanced. It's like having a virtual hand on the volume control, gently turning it up or down as needed. This makes the vocals fit better in a song or speech, ensuring they don't get lost or overpower other sounds.
Too Much Compression Could Cause Problems
When applying compression, it's important not to overdo it. Too much compression will accentuate breath sounds or increase sibilance.
You also don't want to squash the life out of the performance. Depending on the style of music, the amount of stylistically appropriate compression will vary greatly, but invariably we want to retain a degree of human expression.
How do you know if vocals are over-compressed?
As mentioned above, this can vary from style-to-style, so your ears need to be the judge.
Generally, if too much compression is applied, the voice may lose its natural dynamics and emotion, sounding flat and lifeless. The ups and downs in volume that give a performance its expressiveness can be squashed, making everything sound equally loud. This can rob a vocal performance of its excitement and energy.
Additionally, over-compression can bring out unwanted noise or make the voice sound unnatural and "squashed." In short, while compression can be a useful tool for balancing vocals, using it excessively can take away the life and character of the voice, making it less engaging to the listener.
Use Gain Automation Before Applying Compression
In many instances, I recommend applying gain automation to the recording in your DAW before applying any compression.
This initial step is a favourite trick by pro engineers to even out a performance and reduce any potential breath issues that may cause the compressor to work harder.
To benefit the compressor, this automation must occur at the beginning of your signal chain.
Channel gain is not the same as output volume. So adjusting the volume fader will achieve nothing if we want to change what our compressor receives.
Evening out the gain of a performance using automation will make setting the compressor threshold much easier. If the level coming in is very erratic, we could struggle to find an appropriate threshold to suit the louder and the quieter parts of the recording.
As compression shapes the tone of a sound to some degree (particularly the transients), having the compressor work very hard on the loud chorus parts (for example) and only subtly (if at all) on other sections could lead to a dramatic variation in vocal tone.
For the purpose of example, we're using Logic Pro, which has a gain plugin you can place on the insert of any channel. As pictured below, we can then use automation the adjust the input gain before going out to a compressor.
