In­side ev­ery bass note…

Computer Music - - Make Music Now -

Play a note from a saw wave os­cil­la­tor – any note, not just bass – and check out the re­sult­ing sound on a fre­quency anal­yser. What you see are a se­ries of har­mon­ics, start­ing at the fre­quency of the note you’re play­ing, and con­tin­u­ing at in­ter­vals of that fre­quency. For ex­am­ple, in the im­age be­low we’re play­ing an A2, which is 110Hz. We see a har­monic at 110Hz, then the next at 220Hz (110 x 2), another at 330Hz (110 x 3), 440Hz, 550Hz, 660Hz and so on.

Switch the os­cil­la­tor to a sine wave, though, and you should only see one of these har­mon­ics – the orig­i­nal 110Hz (if you see more, you may have some dis­tor­tion in the sig­nal path). We can ac­tu­ally start to recre­ate the saw wave by play­ing just sines, adding to the orig­i­nal A2 (110Hz) note with the notes A3 (220Hz), E4 (about 330Hz), A4 (440Hz), C#5 (about 550Hz).

We could keep go­ing, but we’d need a lot of fin­gers. What we’re try­ing to get across is that a bass note – as long as it’s been made us­ing a ‘com­plex’ os­cil­la­tor (ie, not just a sine wave) – ac­tu­ally con­tains many har­mon­ics at many fre­quen­cies, and these fre­quen­cies are mu­si­cally re­lated to each other.

You can find these har­mon­ics in al­most ev­ery sound we con­sider mu­si­cal: a synth, a string, a trum­pet, a clar­inet, a vo­cal and any­thing else. The ‘times two, times three’ re­la­tion­ship is usu­ally the norm, although some in­stru­ments – a xy­lo­phone or a bell, maybe – have dif­fer­ent re­la­tion­ships be­tween their har­mon­ics. The point we want to get across here, though, is that when you cre­ate a bass sound, it con­tains en­ergy in the low­est fre­quen­cies, sure, but there’s also much more hap­pen­ing fur­ther up.

Bass and EQ

So while your ‘bass fre­quen­cies’ are al­ways low, your ‘bass sound’ might take up a far broader range of fre­quen­cies, with the sub bass, bass, low-mids, high-mids and pos­si­bly even the high­est fre­quen­cies play­ing a role in the sound. That means that it’s help­ful to iden­tify which parts of your patch, sam­ple or in­stru­ment are giv­ing it the char­ac­ter it has, in or­der to em­pha­sise or de-em­pha­sise each of them while mix­ing the bass into a mul­ti­track mix.

In the low-mids (250Hz - 1kHz), box­i­ness can be a bad qual­ity you’ll want to cut, while boost­ing might em­pha­sise any warmth al­ready present in the sig­nal. In the high-mids (1 - 4kHz), you might find the ‘nose’ of your bass sound; the area that gives it its bite and helps it at­tack fur­ther up the fre­quency spectrum. This may be more a hang­over from bass gui­tar mix­ing tech­niques, though, and for syn­the­sised bass sounds, it’s pos­si­ble to give a sound a char­ac­ter of your choos­ing by adding a lit­tle some­thing ex­tra at these high-mid fre­quen­cies.

No size fits all

We’re avoid­ing giv­ing you spe­cific fre­quen­cies and recipes for bass here for a rea­son: your bassline and your whole track will de­ter­mine which fre­quen­cies need care and at­ten­tion, and why. From synth sounds and tim­bres to note choices, the num­ber of in­stru­ments and the ar­range­ment – no­body can tell you ex­actly which fre­quen­cies to boost, re­duce or chop off com­pletely, be­cause dif­fer­ent tracks con­tain en­ergy and char­ac­ter at en­tirely dif­fer­ent places. We’re afraid it’s time for us to pull out the old ‘use your ears’ card here.

Top: A saw wave os­cil­la­tor play­ing an A2 note – we can see har­mon­ics at 110Hz, 220Hz, 330Hz, etc. Bot­tom: The same note on a sine os­cil­la­tor cre­ates only one spike, at 110Hz

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