Written 1999/07/30
When I first wrote about the freeware synthesis program Visual Orangator way back in issue 2, I hadn't attempted additive synthesis with it, nor did I fully understand the possibilities of the harmonic generator module. Now that I've done both, I'd like to share my tips on creating additive sounds using this great software.
But first thing's first: additive synthesis involves mixing many sinewaves (called partials) to create a more complex sound.
When I first made additive sounds with VOran, I did it the hard way: I mixed a slew of sinewaves together, set different frequencies for the partials, connected some linear envelopes for dynamic changes in amplitude, and spent lots of time tweaking the overall mix. The sounds I produced where quite pretty, but the whole process of setting up oscillator after oscillator got pretty tedious, not to mention having to set all their frequencies at pleasant harmonic intervals. For this reason, (as well as the tremendous amount of my computer's resources additive sounds take) I seldom went past 25 oscillators.
It wasn't until I understood the harmonic generator that I found an easier way. When you access the parameters page of the generator you'll see the sliders that control the amplitude of the harmonics are setup to produce a rough sawtooth wave. By connecting it to an oscillator's custom waveform input and selecting "custom" in the oscillator's parameters, you can hear this sawtooth. If you go back to the generator parameters and reduce all the sliders to minimum except the one on the far left, you will be left with a sine wave which plays at the amount of Hz specified on the oscillator's parameters. This is the fundamental frequency. Now when you gradually increase the harmonic sliders, the waveform will change shape as harmonics are added. Let me tell you, I nearly soiled myself when I realized all the time this module would have saved me, had I only known...
Well, now you know!
But one of the compromises of this shortcut to additive is that a single oscillator connected to a harmonic generator is rather static. You could connect an envelope or LFO to the amplitude input, but still all the partials will be proportionate in volume. The precise dynamic modulation of each partial's amplitude was the sole merit of the hard way.
The solution is a combination of the two techniques. Have a harmonic generator (or more, if you like) connected to several differently-tuned oscillators. These separate, harmonic-rich oscillators can now have completely different amplitude modulators. Finally you will be able to make sounds that are both complex and dynamic, without slowing or even crashing your computer.
To conclude, additive sounds have a certain purity about them. They can conjure descriptions such as "bell-like", "Japanese", "shimmery", or "real purdy-like". Done well, they have a timbral beauty all their own, and are well worth the effort.
Also download my Visual Orangator presets at the Sounds page
