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This Month’s Module:
 MOK Waverazor Dual Oscillator

Chris Meyer

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Create your own Frankenstein’s monster of a waveform by splicing together multiple waves.

Splicing together multiple waveshapes to create a new composite wave is an increasingly popular synthesis technique. The output contains harmonics from each of its component waves, with an overlay of higher harmonics whenever the splices between waveshapes creates a discontinuous jump in level. Modulating the source waves or the splice point varies the resulting harmonic series. The result is usually an unabashedly bright, aggressive, noisy sound, with a lot of animation.

Waverazor was originally available as a software synthesizer. MOK has ported its oscillator section to 1010music’s programmable hardware platform. It features a large color LCD touchscreen, two pushbuttons for menu navigation, four continuous rotary encoders, four input and output jacks each, and 20 jacks for modulation inputs. The module supports two oscillators, each with its own slices, settings, and modulation inputs. You can control it with either CV or MIDI.

Understanding the Algorithm

To get a better handle on how wave splicing works, let’s walk through a simple example.

In the image below, I have set up one of the Waverazor’s oscillators to have two segments, spread evenly across one full cycle of the final composite wave. Using Waverazor lingo, this means the Number of Steps is 2, and the Step Size is 1/2. The first segment uses a sawtooth wave; the second uses a sine.

Even though each wave is present only part of the time, you will hear “ghosts” of their harmonic content overlaid on top of each other. In this case, the resulting harmonic spectra is a mixture of the sawtooth (every harmonic present, steadily decreasing in strength at higher frequencies) and the sine (just the fundamental present).

With a Step Size of 1/2, the “razor” is splicing segments at twice the waveform’s fundamental frequency. Since two splices happen per final wave, the act of splicing introduces a harmonic component that is shifted up one octave from the composite wave’s fundamental. A smaller Step Size would shift this component higher; larger Step Sizes can introduce subharmonics.

Both the sawtooth and sine waves cross the center line halfway through their cycles. When we splice together one-half of a sawtooth with one-half of a sine, they line up at their segment boundaries. As a result, no additional high harmonic content is added by these splices.

However, altering the phase offset of one of the waves changes where they join up, which in turn introduces additional harmonics.

Harmonic Madness

Detuning the pitch of one of the waveform components changes the frequencies of its ghost harmonics. This creates the effect of a pair of detuned oscillators chorusing or beating against each other, with harmonic spikes that no longer maintain a nice, clean integer relationship. And since they are being spliced together rather than mixed, the discontinuities at the segment boundaries again contribute additional harmonics to the final mix.

You can see how complex the final harmonic spectra can get with just this simple example. As you start introducing more splice segments and modulate their parameters, the resulting harmonic stew quickly becomes quite complex, buzzy, and animated. 

In addition to editing each wave slice by hand, the Waverazor also offers sync and amplitude modulation. A set of “X” control parameters can also adjust the tuning, volume, or phase of all of the splice segments at the same time, but by different amounts. These all provide quick access to more harmonic madness.

Using the Module

The MOK Waverazor divides its user interface into two sections. Pressing the Home button in the upper left gives you quick access to the two oscillators, including the ability to see their respective composite waveforms. The front-panel encoders are dedicated to coarse and fine tune, with six additional parameters across the two pages per oscillator. There is also a graphic X/Y modulation section that you can drag with your finger.

Pressing the Info button in the upper-right corner accesses deeper controls per oscillator. These include fine-tuning the setting of each individual wave, setting up offsets and scaling for each of the control voltage inputs, and overall system controls including MIDI continuous controller assignments corresponding to the CV inputs.

The Waverazor makes good use of the display’s touch properties. In addition to the X/Y performance controller mentioned above, touching a parameter resets it to its default value—particularly convenient for tuning adjustments. You can also reset the component waves to their original phase offsets by touching a Phase Reset button in the top right corner of the Home pages.

Interface Issues

However, despite the size of the display, the MOK Waverazor is not as fast or friendly to use as you might expect. The default colors are dark (I’ve changed them for the illustrations), and the parameter names and values are small. The highly useful oscilloscope display is not available for any of the Info pages, which is where most of the nitty-gritty editing takes place. In most cases you can’t edit more than four parameters per page…and the Waverazor has a lot of parameters, especially as you use more slices or get into controller mapping. Also, some of the user interface options—such as which sound-engine parameters an encoder controls—can’t be configured on the module itself. 

Therefore, power users will want to get the software user interface (currently in beta), which more closely resembles the Waverazor software synth.

Patches you create with the software interface can be saved from your computer onto an SD card, which you then load into the front of the module. You can have up to 512 presets arranged in 64 banks. The Waverazor also comes with a number of presets that provide good starting points for your own explorations.

Razor’s Edge

The MOK Waverazor is a very deep, flexible Eurorack module that will take a fair amount of time to navigate and master. However, if you like swarming, metallic, noisy, aggressive sounds, you will find an endless supply of them here.

Website: 1010music.com

Price: $600

Synth and Software would like to thank longtime modular user and former synth designer Chris Meyer for his contribution. Chris is the force behind Learning Modular, where he teaches how to master modular synthesizers.

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