Getting the low end right in the mix can be elusive. There are the tried and trusted ways that can get the engineer to subsonic nirvana, but some issues call for more than a couple of EQ scoops or fader rides. We show you how…
Even the simplest of mixes will often have at least a couple of low end elements as its foundation. The first consideration should really be where these parts live in the frequency spectrum, the second one is when the parts should happen, as any nifty placement of kick or bass on the offbeat demonstrates.
These conventions are much older than recorded music itself. Nonetheless, engineers still often find themselves tasked with getting around musical anomalies arising from the arrangement; no single genre is safe!
Spectral Overlaps Are Bad, But Why?
These occur when the arrangement forces mix elements to tread on each other’s toes. While high frequency overlaps can be fatiguing for the listener, the mid-range is critical on the understanding that the whole message is in the middle.
Low frequency instruments in particular can occlude each other in a part of the spectrum that arguably causes the most headaches in terms of mixing and monitoring. Certainly, the ear is far better at unpicking mid range mess than it is low frequency murkiness, but there is another consideration at play: headroom.
A subjectively well balanced mix can look decidedly lopsided on an analyser, revealing the necessary low-end tilt to achieve that balance. This has implications for mix headroom, as bass needs more to be heard at the ‘right’ level. Therefore it goes that when it comes to mixing the low end, there’s a technical reason as well to keep overlaps in check.
Ducking Versus EQ
Perhaps the simplest way to manage overlaps is to employ some kind of level control, whereby one element’s presence dips the other’s level. This can be achieved using a dedicated ducker, or compression set up to behave like one. Alternatively, simple EQ dips at the most effective frequencies can help, but these inherently change spectra in ways that can rob an element of its character all of the time. Step forward a third way…
Ducking With EQ
The natural way around the shortcomings of conventional subtractive techniques is to use a dynamic process. By ‘triggering’ EQ cuts that occur at specific times (such as on kick drum hits), other bass instruments can have overlapping frequencies dipped during specific events in the music.
In the video, we use FabFilter’s Pro-Q 3 to create a spectral ducker across a bass guitar virtual instrument. We route the kick into Pro-Q 3 as the sidechain input, before using its spectra to inform cuts to the bass guitar. We settle on two cuts; one at the kick’s fundamental frequency, as well as having a second filter in hand to play down plectrum sounds versus beater click for good measure.
Keeping The Low End
Listen to classic records, and regardless of genre, it’s not uncommon for there to be a thinner kick over a fatter bass or vice versa, requiring nothing more than a humble low cut filter on one channel. This classic technique is of course still highly effective, and perfect if a vintage aesthetic is sought.
Low cut filters are far better than nothing and there to be used. Moving up the same ladder, spectral ducking can be better still, and is also there to be used. Being able to knock an instrument into shape exactly when needed and still retaining much of its personality is the best of both worlds indeed.