The 4ms SWN is more than a wavetable oscillator module; it’s also a powerful six-voice drone and generative music device.
More powerful microcontrollers are having a profound impact on the world of Eurorack modules—oscillators, in particular.
Most analog oscillator modules produce just a single note or voice. If you want two voices, you must essentially double the amount of hardware, with size and price not far behind. By contrast, microcontrollers that previously were just powerful enough to create one oscillator voice can now create two, four, or more with virtually the same amount of hardware, size, and price. The challenge has now become how many jacks, knobs, and switches to add to access that power. Another challenge is writing software to coordinate those voices in interesting ways.
An excellent example of this is the 4ms Spherical Wavetable Navigator (SWN). It is a six-voice instrument, with one wavetable oscillator, VCA, and LFO per voice. You can treat the SWN as a single, fat, six-tone crossfading wavetable oscillator with chords and detuning. Or you could treat it as six independent oscillators for polyphonic applications. But what makes the SWN particularly charming is the way it can coordinate those six voices to create arpeggios, evolving drones, and other musical delicacies in between and beyond.
Wrap Your Head Around the SWN’s Wavetables
How does the SWN crossfade between waveshapes? 4ms initially describes it in their manual as a set of three spheres—one inside the other—that you can navigate by Latitude, Longitude, and Depth. Once you get deeper inside the manual, they describe it as 3-torus—a three-dimensional structure existing in a four-dimensional space.
Personally, I have found it easier to think of the SWN’s wavetables as being arranged as a cube built from an array of 3x3x3 waveforms. What’s the difference between it and other crossfading wavetable oscillators? When you reach the edge of the cube, you don’t stop; you wrap back around to the same place on the other side and keep going. That means when you turn one of its wavetable navigation encoders, the result is a continuous morphing of the sound without stopping or doubling back on yourself.
However you picture it, 4ms refers to the resulting wavetable as a Sphere. Twelve Spheres are built in, along with memory slots for an additional 108 User Spheres. You can record up to 2.5 seconds of audio into the SWN and have it slice it up and process it into a new Sphere. A free SphereEdit program is available on macOS, Windows, and Linux. It allows you to create, edit, import, and export waveforms and Spheres and then load them into the SWN. You upload these computer-generated Spheres—as well as update the firmware—by playing an audio file into the module.
Spread the Love (er, Channels)
To give you a taste of the flexibility offered by the 4ms SWN, here are a couple of common scenarios for manipulating it.
When you first power on the SWN or load a blank preset, all six channels are set to the same waveform and frequency (unison). Turning the Transpose control shifts all six channels up or down by semitones. Holding the Fine button while turning Transpose offsets them smoothly by smaller increments; there is also an Octave encoder.
Pressing and turning Transpose (Spread mode) assigns each channel to a different note in a chord. At this point you realize you’ve spread the channels across the stereo field. Holding Fine down while pressing and turning Transpose detunes the six channels from each other. This is particularly effective when in unison mode, creating effects ranging from gentle chorusing to inharmonic noise. To mute a channel, press one of the six buttons along the top of the module. To tune one channel differently from the others, press and hold that channel’s button and then perform any of the above gestures.
Similarly, to change the waveform being played, turn the large Browse encoder, which steps through the 27 individual waveforms that make up a Sphere. To change Spheres, press and turn the Browse encoder. If you want to smoothly navigate between the waveforms in a Sphere, turn the smaller Depth, Latitude, and Longitude encoders.
To offset which channel is playing which waveform, press and rotate the Depth encoder (Dispersion mode). This is akin to detuning the parts from each other, but in timbre rather than pitch. Pressing and rotating Browse (or rotating Depth, Latitude, or Longitude) will move all of the channels together while keeping the Dispersion you have set up. To edit each channel’s waveform individually, press its Channel button and do any of the above.
That may sound like a lot of information to keep in your head at once, but the user interface helps. Any knob’s primary function is printed below it, and its secondary press-while-turning function is on a gold background below that. LEDs for the channels that are arranged around the Browse encoder also give clues as to which channel is offset to which note, how the pitch and waveforms are offset, etc. I found that I could quickly memorize basic functions such as the above. Tweakier edits will require refreshing your memory using its refreshingly thorough manual.
Sliders allow you to edit the mix between channels. However, you can also modulate this mix as well.
The SWN has one LFO per channel, pre-patched to an internal VCA per channel. Press the LFO —> VCA button, and now those LFOs control the volume of each channel. By default, they are offset 60° in phase from each other to create smooth crossfades or cycles through the channels.
As with tuning and timbre, you can adjust the LFO waveform, speed, and musical division globally or individually; there is also a master clock input. The LFOs also each has its own CV output. If you prefer to control the VCAs externally, a switch changes the function of another row of six jacks to either be the 1V/oct pitch CV or VCA level per channel.
Something to be aware of when controlling the SWN externally is that it only responds to positive control voltages. For example, pitch control is 0 to 10 volts. To control parameters such as Depth and Latitude, you need to offset a normal bipolar LFO or random voltage to be just positive, and scale it down to a range of 0 to 5V (For comparison, the standard for most new modules is either -5 to +5V, or 0 to 10V.) It makes sense for the VCAs to be unipolar, but for ease of use, I wish the other CV inputs were bipolar.
The examples above just scratch the surface of what is a very deep module with a lot of control. This is not a module you’re going to master in one day. In the way many treat iconic instruments such as the Buchla Music Easel or EMS VCS3 as self-contained instruments that they devote their life to exploring, you can think of the 4ms Spherical Wavetable Navigator as a similarly deep heart of a compact intentional or generative music composition device.
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.