Pitch and awe
A good drummer thinks of his drums as pitched instruments – just as any other instrument can be tuned to the key of a song, so too can drums. At the very least, the drums might be tuned to avoid buzzing and dissonant sounds, but in the unforgiving environs of a recording studio, it’s likely that the drums will be tuned to each song.
In addition to their basic pitch, note that drums change in pitch as they ring out. Think about a tom or timpani: there’s a clear downward sweep as the hit fades. As we learned in the previous section, you can use an envelope generator to control amplitude and filter frequency over time, so it’ll come as no surprise that you can simulate a drum’s change in pitch by modulating the tuning with a simple ADSR
(or even ‘AR’) envelope. Subtle changes in pitch will result in realistic tones, while exaggerated bends are used for the classic ‘disco tom’.
The pitch envelope can play another important role in the creation of drum sounds – an almost imperceptibly fast pitch sweep, for example, can add a lot of bite and aggression. The ear won’t hear it as a change in frequency, just as a burst of energy.
What if your synth of choice doesn’t offer a dedicated pitch envelope? It may be that it has an assignable modulation envelope that you can use instead. Of course, some instruments only have one or two envelopes. That’s OK, too – as long as there’s some means by which one of them can be connected to the pitch of the oscillators. This may be achieved using a modulation matrix. Many synths come equipped with one – they allow a number of modulation sources to be specified and connected to specific destinations, and oscillator pitch is invariably among those destinations.
We’ll be delving into the mod matrix and envelopes over the next few walkthroughs. We’ll also learn a bit about using some basic modulation effects to impart a metallic, ringing tone to certain sounds – most specifically to recreate the classic Roland CR-78 hi-hat sound so beloved by electro-pop legends Gary Numan and Ultravox, among others.
“It's important to realise that drums change in pitch as they ring out”