So, we’ve addressed two important processing tools available to a mix engineer – EQ and compression. Next up is one of my favourites – saturation. How can saturation be useful for bass?
Saturation can do a number of things simultaneously – it can reduce the headroom requirements of the track, it can make the bass more audible on smaller speakers (and more powerful on larger speakers), and it can help it sit more consistently in the mix.
Saturation reduces the headroom requirements of a track in a similar way to a limiter (or compressor with high ratio) – by making sure signal cannot exceed a certain level. This “chops the tops off” the loudest notes, bringing them down to the level of the other notes. Unlike limiting or compression, however, saturation doesn’t do this by actually reducing the volume. Instead, using the saturation the loudest notes are distorted a little. The net effect is that pure volume is transformed into noise. Another way of looking at it is that lower-frequency energy is turned into higher-frequency energy.
What does this actually sound like?
It should sound like the bass is at the same level, but instead of stronger notes getting louder, they get noisier. Applying saturation with a deeper threshold (so that most notes are saturated, not just the loudest ones) makes the whole bassline sound noisier. What’s actually happening is that upper harmonics are being generated. Because the bassline is monophonic (single notes at a time – not chords), the harmonics being generated are related to the pitch of the bass. Because these harmonics are at a higher frequency, they’re audible even on smaller speakers that can’t reproduce the lowest bass sounds. This means that your bassline will still be audible without requiring large speakers. You don’t even need much saturation for this to occur. On larger speakers, the upper harmonics reinforce the bass, making it sound more powerful.
As for actual selection of tools and settings, you’ll have to experiment. There are a wide variety of different methods of saturating a sound, and there’s a wide variety of different sounds available. Aside from some kind of “drive” control, saturation processors don’t have standardised controls in the same way that EQs and compressors do. Just remember that less is usually more – you don’t need to push the bassline into full distortion to achieve a useful saturation effect.