The science of bass
For some it’s all in the heart, but if you want to get your head around atom-shaking bass, here’s the lowdown on the down-low
This issue, we're all about that bass, and while we'll take you through tips, techniques and walkthroughs to help you get the baddest, most heavyweight bass around, we're going to kick it off with some science. If that doesn't sound like you, feel free to flip a couple of pages ahead, but if you're able to digest a bit of Acoustics 101, we can help your bass grow big and strong with some help from mother nature.
When most people talk about bass, they’re talking about low frequencies in general. As producers, though, we get a bit more specific, breaking it down into bass (about 60Hz to 250Hz) and sub bass (everything below 60Hz). But man cannot live on bass alone – as you’ll find out, other parts of the frequency spectrum play a part in helping us craft bigger bass, too.
Bass is big
Sound is caused by pressure variations in the air, and every frequency has a corresponding wavelength – an actual distance in metres, centimetres or millimetres that one cycle of the wave occupies in the air around us. A tone of 700Hz occupies about 50 centimetres in the air, for example, while 3kHz takes up roughly 11cm.
Bass, on the other hand, is all about the big waves. A heavy 40Hz wave occupies about 8.6 metres in the air – it’s massive. So the lowest parts of our beloved bass are, quite literally, heavier, which is why a large speaker cone is necessary to truly and accurately play back these frequencies.
The lowest tones surround us totally, interacting more with the space around us than simply with our ears. In home studios, the lowest bass travels more easily through solids like walls, floors and furniture than it does through the air – but we didn’t need to tell you that sub bass is primarily felt rather than heard, did we?
The lowest of the low
Working with bass means you’re working at the limits of human hearing, and the limits of what speaker systems are actually able to pump out.
MIDI note A1 will throw its lowest sound out at 55Hz. That’s low, but we can go even deeper – A0 will hit at half that frequency: 27.5Hz, getting right at your chest. We’re getting close to the limits of human hearing, but we can go further still – the generally accepted lowest frequency we can hear is 20Hz – that’s between MIDI notes D#0 and E0.
How do these huge, slow waves look at the surface of a speaker? The lowest tones need larger speakers. As large speakers shift more air, there’s a lot of movement going on; often so much that it becomes visible.
With so much movement happening at the speaker cone, it’s possible to demand too much from it by feeding it too many low-frequency signals in quick succession – imagine the double kick drums of metal, for example, which can easily lose impact for individual hits, turning into a wash of ill-defined bass if a soundsystem’s speakers and limiters are too slow to react.
You can’t guess at every playback system’s capabilities, but you can allow for quirks. Leave a short gap of silence between bass notes rather than running one straight into the other, and carefully mix your kick and bass signals, to help ‘reset’ the playback system and get the impact you want. Given that large clubs have a certain amount of reverb present anyway, you might not notice a thing.
Every frequency has a corresponding wavelength it occupies in the air around us – the lower the frequency, the larger the size of the sound wave