With the online tools available, there are many paths to the same goal when it comes to producing music. Plenty of tools are created to simplify creation processes, and many more can be used in place of each other. One of the most interesting is the divide between producers who like to sidechain their bass and kick, and those who like to use an LFO tool to achieve the same effect. Today we explore the differences between each, and which you should choose to do the right job.
So for starters, let’s look at what the desired effect is. When we sidechain-compress a track, we use a sound to trigger the compressor of another track. In the case that a kick drum triggers another instrument’s compressor, that instrument will dip in volume every time the kick drum plays, creating the iconic bouncing effect of sounds around the kick. This effect can also be recreated using an LFO to modulate the volume of a sound in time with the beat.
This effect isn’t just a creative choice for an iconic dance sound, it also serves an extremely valuable purpose. When mixing a track, the low-frequency sounds can add up quickly and cause problems. To solve this, it is best to limit the amount of low-frequency sounds playing at the one time. Of course, you don’t want to re-write your basslines so they never coincide with the kick drum, instead, we can use the sidechain compression (or LFO) effect.
Because the bass dips in volume every time the kick plays, it means that there is more room for the kick to punch through. Even subtle amounts of sidechaining can be a really useful tool in this case, where you don’t want the characteristic EDM bouncing, but you want the functionality of the effect.
Benefits of Using a Sidechain Compressor over an LFO
One of the main benefits of using sidechain compression itself over an LFO mimicking the effect is that it is responsive. A sidechain compressor reacts to the audio being sent to it. This means that if the kick is dynamic and expressive, the sidechain compressor will respond accordingly, preserving more of the bass on the quieter kicks, and carving out more on the louder kicks.
Because it is responsive, it also allows for kick pattern variations. Whenever the kick drum hits, whether it is on or off-beat, the sidechain compressor will react. This is a major benefit over LFOs which are really only able to follow a 4-to-the-floor kick pattern.
They are able to respond to more complex audio as well, a popular example is sidechaining pad synths to vocals. Obviously, vocals contain much more dynamic and rhythmic variety than your standard techno kick pattern, and so a sidechain compressor is the most ideal way to respond to the audio.
A really useful technique for instruments sitting in the “Muddy” areas of a track is to use two sidechain compressors, one triggered by the kick drum, and one triggered by the bass. If used on a synth patch, it will allow much more room for the important lower-frequency elements. As seen below, an EQ takes out the lowest frequencies, a kick triggered compressor frees up the room for the kick, and a bass triggered compressor can be used to carve out space for the most intense bass notes, particularly the transients.
One downside of a sidechain compressor is that sometimes you want the EDM-like bouncing effect even when your kicks aren’t hitting. Particularly in the builds and bridges of EDM tracks, the sidechain effect can be prominent despite there being no drums. This can be solved without needing an LFO, by using a ghost kick track. A ghost kick track is a track which features a kick drum on every beat (or following the main pattern), but not being sent to the master. This means that there can be the same effect without the audible kick. Ghost tracks also allow for you to use a different kick to trigger the compressor, this could be handy in genres such as techno where you want a shorter kick to trigger the sidechain, while the audible kick is a long drawn out 808.
Benefits of Using an LFO Over Sidechain Compression
An LFO plugin offers benefits too! One of the biggest benefits of using an LFO is the simplicity. You do not need to worry about track routing when using an LFO plugin, such as Kickstart, this is because the plugins do not require triggering (though many also can do this). A major plus of not having track routing is the ability to freeze certain tracks without affecting their parent/child tracks.
LFO plugins also offer much more visual and precise shaping of the curves, which can’t be done with most compression plugins. Xfer’s LFO Tool, for example, allows very precise shaping of the LFO curves in much more detail than what any compressor could possibly achieve, and so for many applications, particularly if combined with some of its other powers, it may be more suitable for the sidechain effect.
Many of the curves on offer are going to be perfect for sidechain effects and by selecting through the different shapes, you can find the best one to suit your kick. And so if that is all you need, the ease of use certainly outweighs the complexity of setting up a sidechain.
Something to note here is that many synths come with advanced LFOs built into them. If you own a synth such as Serum, it basically has Xfer’s LFO Tool built into it. For sheer simplicity, using the LFO in Serum to do this means you don’t use any additional space in your FX rack/chain and everything is built into the one plugin. Serum’s envelopes have sidechain shapes built in, for those who are interested in pursuing that direction.
A final thing to note is that many of the LFO plugins available for this purpose also offer triggering. This is normally carried out by receiving MIDI so perhaps the ultimate decision would fall down to whether you are using a sample of a kick, or a MIDI note triggering an instrument. An audio sample would trigger a compressor, while a MIDI file could trigger an LFO plugin (the resulting audio would also be able to trigger a compressor too!).