Catching the Wave…

Sep 24 2009

While sound fanatics are always on the lookout for new ways of synthesizing or processing sound, there are a number of techniques that have fallen in and out of favor over the years, yet still remain useful and interesting. Some of these have been tied to the fortunes of specific companies, as was the case with the Hartmann Neuron, while others have become synthesizer “cult classics.” A favorite technique of mine is wavesequencing. This is one of the hidden treasures in Reason’s mother-or-all subtractive synths, Thor, and one of the many techniques covered in Berkleemusic’s Sound Design for the Electronic Musician, a course I co-authored and teach.

In a digital synthesizer, any basic, geometric waveform used in an oscillator is stored as a digital representation of a single cycle. These are often referred to as a wave or a wavetable, a list of samples that is read at different rates to produce a pitched sound. As this became a popular method of generating sound in the early 1980s, a couple of pioneering instruments allowed users to cycle through a series of different waves while a note was held. The sequence of waves here is also called a wavetable. This produces some evolving timbral effects and rhythmic patterns not available any other way. The first of these instruments was the PPG Wave 2.2 released in 1982, followed by the Sequential Circuits Prophet VS in 1986 and the Waldorf Wave series in 1993. This technology is also incorporated in the Korg Wavestation series which first appeared in 1990. While the original hardware versions of these classics can be hard to come by, Korg has an excellent software version of the Wavestation, and Waldorf markets a software PPG Wave.

We can think of wavesequencing as a kind of “sound movie,” in which each individual wave is a frame. Each wave is assigned an index number, and plays in turn, reading through the list.

Wavetable

Wavetable waves.

Play the wave sequence movie linked below to see how these blend together over time. Although there are a number of ways to sequence these, this is a close approximation of how we’ll hear these in a wavesequence. This is our “sound movie.”

Sequenced wavetable.

Reason’s Thor implements this with it’s Wavetable Osc, one of the six types of classic oscillators available. While most of its parameters provide the typical control of tuning and key-tracking, the Position and X-Fade are exclusive to a wavetable.

The following steps will get you started with wavesequencing in Thor.

1. Open Reason, add an instance of Thor, and choose Initialize Patch from the Edit menu.
2. Change the Analog Osc that comes up as the default to a Wavetable.
3. The first wavetable is Basic Analog. It stores four waves, a sine, triangle, square, and sawtooth. Hold a note and turn the Position knob clockwise. This selects which wave in the table will be heard. As you move the knob, you’ll hear the sound morph between these waves.

Wavetable position.

Wavetable position.

4. The X-Fade function provides a smooth transition between the waves. Click on the X-Fade button to disable this; the red indicator will turn off. Move the position knob again and you’ll hear an abrupt switch between each wave.

Wavetable crossfade function.

Wavetable crossfade function.

5. Each of the 32 wavetables will have a different number of waves. Take a few minutes to select different wavetables and scroll through the available waves with the X-Fade function both enabled and disabled.

6. Call up the table named MixedWaves1. Hold a hold and scroll through the table, as before. There are eight different harmonically rich waves stored here. Turn off the X-Fade function and set the position to 63.

Wavesequencing, as a technique, yields two main timbral effects. With X-Fade enabled, we get a smooth timbral shift that works well for pads, while disabling the X-Fade function is useful for rhythmic effects.

7. The key to either effect is modulation, and Thor’s matrix offers many possibilities. We’ll start with a rhythmic effect This is produced using an LFO to control the wavetable position. In the first slot of the matrix, set LFO1 and the Source and Osc1Pos as the destination. Set Amount to 100.

Modulation matrix settings.

Modulation matrix settings.

8. Thor has a number of evenly stepped LFO waveshapes, where each step will select a specific wavetable position. Select the 8-step sawtooth shape shown below. Play and hold a note and you’ll hear an even progression thorough the eight positions in the wavetable.

8-step sawtooth LFO shape.

8-step sawtooth LFO shape.

Rhythmic wavesequence.

The wavetable we’ve been working with is a collection of eight distinctly different waves. Other wavetables will have a more subtle variation between a common shape.

9. Change the wavetable to PPG2 Bell. This is from one of the classic Waldorf synthesizers. Manually cycle through the table while holding a note and you’ll hear that these waves have a common timbral characteristic, while each has a distinct spectrum.

10. In the Modulation Router, choose Mod Env as the source and keep Osc1Pos as the destination. Set the amount at 100.

11. Set the Mod Env attack time to 1.49 seconds and the decay time to 6.24 seconds. Play and hold a note, you’ll hear a distinct timbral shift here.

Timbral shift wavesequence.

While these examples illustrate the basic idea behind wavesequencing, there are a number of factory patches that offer great examples of this technique. Check out: Kaleidoscope, Relay Stepper, and Scan Dance from the folder of Rhythmic patches for starters.

Surf’s up…

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    Hey MR.B!!!!!! I saw this on Synthtopia and I sent it around to the audio department here at Activision. Goood Stuff!! We will have to meet up for lunch next time I’m in Boston!! Hope all is well. Talk to ya soon Mr.B!
    -Chris

    Wave-sequencing is one of my main tools. I am very inspired by some of Howard Scarr’s patches in Reaktor… And for lo-fi wavey fun Oki Computer honestly also ROCKS.
    Thor is a beast and that’s for sure, but my weapon of choice for this will allways be the Mono Evolver from Dave Smith, the waveshape oscillators sound so close to the Prophet VS it’s almost weird.
    Also the Malstrom in Reason can satisfy if you connect the note CV from a Matrix to the Index modulation jack and go bananas programming notes…
    Wave sequencing is FUN!!!

    Michael, nice to see your up-to-date blogs.

    I’ve always incorporated the wavesequencing technique you taught us in class and I’m using it in creating original sounds for music catalogue submissions as well as for the “arsenal”.

    Fortunately, I got 2 songs already accepted in a music library and most sounds from those successful submissions were from the waveseq techniques learned from class.

    Take care!

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