Tech \ Technique \ Gear Tips

Sub-bass 101

How low can you go?

2019 Jun 30     
2 Bit Thugs

Want to give your tracks some real bottom-end grunt? Chris Lyth has some tips for powering up your productions through the judicious manipulation of those hard-to-hear sub-bass frequencies…

Earth-shaking sub-bass is ubiquitous in modern electronic music, but it’s also one of the more difficult production techniques to accomplish in a typical home studio. This is primarily due to the less-than-perfect acoustic environments which many bedroom producers work in, and of course the small monitoring set-ups they generally work with. 

Sub-bass – just in case anyone's not clear – is a term that refers the very lowest part of the audible frequency range, from 60Hz down to 20Hz. 20Hz is generally considered to be the lowest frequency audible to human hearing, but sub-bass in a club is often felt rather than heard as a pitched instrument. Very few speaker systems are capable of reproducing anything below so 20Hz, so sound in this range is called infrasound and is rarely useful as musical content. 

Luckily. there are a few tricks and techniques at our disposal that can get us a little closer to throbbing sub-bass nirvana…

1. Monitoring

You can't product what you can't hear! It’s extremely difficult to work effectively with sub-bass frequencies when your monitors are struggling to reproduce the low-end energy you're working on. Obviously having a subwoofer in your monitoring chain is going to help enormously here, but it’s not always possible. A good pair of headphones that will allow you to hear below 60Hz are an invaluable mix tool and will take a lot of the pain out of monitoring in an untreated room. Don’t be tempted to go overboard by adding what your speakers can’t reproduce: you will invariably over-cook it and end up with a bloated, swampy mix with no headroom for other frequencies. 

2. Key is important 
As you probably know, pitch, key and frequency are all different names for the same thing. So it’s important to have a decent working knowledge of what frequency you're triggering when you play at the low end of the spectrum.

G is, for me personally, the best key to write in for good sub-bass, but generally anything from F to A works well. C is a particularly difficult key to produce sub-bass in, but as always there are exceptions to the rule. Use a spectrum analyser to see where your bass is peaking. 

3. Use a snappy kick
Only one instrument should live in the sub-bass range at one time, so if you're going for a huge bassline with lots of sub then use a short, snappy kick that won’t eat up the space in the low frequencies that your bassline will occupy. Make your kick punchy by beefing up with saturation and bringing out the 6-8kHz range so that it will find the listener’s ear. Often when we think the kick needs to be louder, we just need more high-mids so it will cut through the mix. If you're using a huge sub-bass to carry the entire track, have the kick peaking in the 80-110Hz region. 

4. A sine of the times
A very common approach to generating sub-bass is to use a simple sine wave, either on its own or layered an octave or two under the higher bass notes. Many classic drum & bass basslines, for instance, were made using the default load-up sine preset in Akai samplers. 

Logic’s EXS sampler gives a nod to this tradition by loading a sine wave as a default. It’s just a case of trimming the envelopes to suit your track, giving you what's almost an 'instant classic' sub-bass generator. Try mixing in a little bit of square wave with the sine to create a thicker tone. 

5. 808 state
A classic technique for growling sub is to load an 808 kick into a sampler and play it as you would a typical bassline. Use distortion (see tip 10) to bring out the midrange harmonics so it will be heard on small speakers. Then add a compressor with medium attack and release (reducing at around -6dB) to keep your notes smooth and consistent, and you'll have booming subs ready to go in seconds. 

6. Making space with EQ 
Almost no speaker system will reproduce sound below 20-30Hz, so it’s a good idea to engage a 48dB/octave high-pass filter at 20Hz on both your kick and bass. You can (depending on your track) take it much higher. Close your eyes and sweep the frequency up until you can hear any adverse impact on your sub. You may well be surprised by how high you can go before your sound suffers. Spending a little on a great surgical EQ like FabFilter Pro-Q3 (which also has a spectrum analyser) wouldn’t be the worst investment of your production career. 

Obviously you'll want to cut the low end out of all other instruments, like keys and vocals, by high-passing up to as high as 150Hz depending on your track. The most important area of the range is 40-60Hz so use a spectrum analyser to view this area and make sure nothing extraneous is creeping in.

7. Shaping the foundations 
The relationship between the kick and the bass provides the foundation of your track, so it’s vital to get them to sit together in harmony. Arranging the kick and bass so that they don’t fall on the same beat together is obviously a great way of keeping the low-end clean and sharp, but it’s not always possible. 

When you're EQing, make sure to solo the kick and bass together and do a little work on them solo’d before switching back to hearing them in the context of the entire track. It’s a good idea to switch back and forth often when sculpting with EQ. Also, switch between speakers and headphones and vary your listening levels. 

8. Feed the aux
A good way to deal with subs in the mix is to create an aux track with a specialised plug-in such as Waves Submarine/Renaissance Bass or Little Labs VOG, and introduce them in incremental amounts as required. Set the mix to 100% wet and then you can send whatever channel you want. As discussed before, only one instrument should occupy the sub, but this could be handy for an FX part in a breakdown, for example.

9. Multiband considerations 
Using a side-chain compressor to duck the volume of the bass when the kick triggers is a fairly standard and effective technique. The only problem with it is that it ducks the entirety of the signal, when we are only wanting the low-end to move out of the way. Using a multi-band compressor can more precisely target the frequencies that we want to be ducked, therefore leaving the bass more present in the mix.

A typical example would be that every time the kick is triggered, everything below 70Hz is ducked by -6dB. Generally aim for as short an attack and release as you can get away with, and play with the threshold and ratio settings to find the right amount of ducking for your track. Be careful to listen out for clicks, solo your bass and adjust attack and release to get it super-tight. 

10. Layer and distort
If you really want your bass to cut through sharply, try layering your sub with a more mid-range sound at a higher octave.This will help it be audible on smaller speakers and will also enable you to sculpt a more unique timbre. Try a multi-band distortion plug-in to bring out some harmonics above 100Hz, leaving the low sub band untouched. Again, this will also help your bass cut through on domestic playback systems 

Producing in small rooms is difficult, but many great sounding records have been made using some of these techniques. With patience, practice and good reference tracks to measure your mix against, chest-rattling subs will soon be yours!

Words: Chris Lyth







Tags: studio tips, production tips, sub-bass, bassline, kickdrum