My introduction to synthesis began with subtractive ways of shaping sound and, later, granular synthesis and FM. For me, it wasn’t until Native Instruments released their now-storied vst Massive that I came face to face with wavetable synthesis and all the possibilities offered by wavetable oscillators.
The analog modeling synths I was familiar with had cross-modulation controls that let you do some interesting wave-shaping, but none of that prepared me for how cool it would be to design sounds using wavetables. So, what is a wavetable? MAGIC! Just kidding (kinda), but imagine this: You have a single-cycle waveform, like a square wave. Now we come to the “table” part of wavetable.
First, think about pulse-width modulation on a square wave (pick any synth you like) — it allows you to change the proportions of the wave-shape, creating semi-evolving sounds. Back to wavetables. Imagine you have twenty index cards, and on the first one is a regular square wave. On each successive index card, the square wave’s width changes slightly closer to the left side. Now, imagine flipping through those cards from first to last.
That’s kinda what a wavetable is: A collection of single-cycle waves that change sonically as you flip through them from first to last. If you take enough of those single-cycle waves, stack ’em together from first to last, and rendered it in 3D, you would get something like this:
Where the magic happens lies in scanning through the wavetable (i.e. collection of single-cycle waves). Imagine you set an LFO to a half-measure and a sine wave, and you route it to the wavetable. (NB: usually this is called something like wavetable index or position.)
Adjusting the depth of modulation to whatever you like, you will hear the sound change as the LFO modulates the wavetable position. As you scan through the wavetable, you get an evolving sound with movement — something dynamic. Which brings me to interpolation.
Most wavetable synths offer some control over what’s called interpolation, which refers to the way the synth handles scanning the single-cycle waves: It can smooth over transitions so they sound gradual, or it can dial in sharp changes from wave-to-wave. Here is one example of how a waveform changes over time while scanning a wavetable:
Notice how the complex waveform generated changes somewhat gradually as the wavetable is scanned/modulated. Again, this interpolation can be adjusted in most cases to give you smooth transitions or rough jumps from wave-to-wave.
Depending on the wavetable synth or soft-synth you get your hands on, you’ll have access to a collection of wavetables. If you’re into soft-synths, check out Massive and Serum. If you’re looking for hardware, Microwave is a vintage option, or grab a Blofeld or Mininova. The Blofeld even lets you upload your own wavetables, or ones you’ve downloaded.
Together, these collections of wavetables serve as the building blocks for this mode of synthesis. Here are a few Massive wavetables ported over to Serum:
Check out some tutorials on YouTube for whichever synth you choose to experiment with. There are tons of ’em out there that go into much greater detail than I have here. Explore, and have fun!