Modular Monthly

Make the most of utilities and voltages

Erica Synths are a perhaps lesser known Eurorack brand who have been releasing extremely solid, well thought-out and just plain interesting modules for several years now. They’re maybe best known for their Polivoks range of both pre-built and DIY modules (you can build complete systems from their modules), trademark black panels and fluted knobs, and a classy design aesthetic, which is sort of like a mashup of Formanta and Shadow Hills Industries in one.

To complement their range of analogue VCOs and filters in the ‘Black’ range, the folks in Riga have just brought out a new (black) digital wavetable VCO, named, appropriately enough, the Black Wavetable VCO (BWTVCO). We’re massive fans of wavetable synths and digital modules in general (indeed, all the standalone oscillators we own are digital), so we’ll preface this by saying they’re preaching to the converted here. A wavetable VCO is always a great complement to analogue VCOs, and with a good selection of basic waveforms onboard (as we do have here), may be all the oscillator you need, though many in Eurorack can be arguably a bit wild for that…

Indeed, wavetable VCOs are certainly nothing new in Eurorack so it’s a tall order to offer something new in what is, as ever, an intimidatingly crowded market. The BWTVCO goes up against longstanding favourites like the Harvestman Piston Honda, Synth Tech E350, Intellijel Shapeshifter, Mutable Instruments Braids, WMD Gamma Wave Source, Richter Megawave, and the cheaper Waldorf nw1, all of which have their own personalities and tricks up their sleeves. Like others, the BWTVCO features the possibility of adding more wavetables via three chip slots on the rear; two are pre-filled, one empty. These are accessible around the back, and of course you could potentially replace them all. Erica Synths say that a third chip should be available to buy separately later at a very reasonable 10 euros apiece, and they mention the possibility of a service allowing customers to purchase chips pre-flashed with their own submitted wavetables.

As it ships, it comes pre-filled with two chips, containing a total of 16 banks of 16 wavetables each (that’s 256 total, maths fans), and a well considered and broad collection of waves it is – more on that in a moment. The key hook with the BWTVCO is that, while bank selection is instant (we tap the bank button to cycle through them), we smoothly morph through the wavetables themselves with a knob. So in fact, those 256 wavetables are really just the tip of the iceberg; there is no discrete wavetable ‘quantising’, so any setting in-between those 256 locations offers new hybrid in-between timbres, and marvellously we can use external CV to both step (instantly, but clicklessly) between banks, and smoothly morph the wavetables at the same time, leading to all manner of rhythmic timbral madness when jamming with the BWTVCO under sequencer control – a Music Thing Turing Machine, with its repeatable randomness, is an excellent modulation companion for this kind of feature.

We should point out that the wavetable morphing concept is certainly not a unique feature, several other wavetable VCOs can do this too, but that the BWTVCO is both physically smaller than all of them, and, most importantly, it’s (currently) one of the least expensive. The only cheaper ‘competitor’ would be the Waldorf nw1, which for a variety of reasons (see 6/10 review in issue 299) we didn’t recommend.

The included wavetables cover a thoroughly solid range of ‘places’ you’d want to go sonically, starting out with very accurate traditional waveforms (sine, saw, square etc), and with that inbuilt morphing providing forms of pseudo-PWM, as it blends from shape to shape. Some of the wavetables are quite cleverly prepared so as to provide a simulation of a filter sweep (which it doesn’t quite manage but still sounds interesting) – to ‘FM’ timbres which simulate through-zero modulation of an oscillator (which do sound pretty convincing) – all by just sweeping the Wave CV parameter. You have classic Wavestation and ‘Megawave’ tones, AEIOU vowel progressions, formant tones, organs, strange harmonic tones and collections of fizzier, grittier, digitally generated wavetables in various forms.

Unlike some of Eurorack’s nuttier Wavetable VCOs, the wavetable tone and quality here is actually rather clean and high quality. We do have a bitcrusher to add ‘fur’ to the output at lower settings, and completely devolving the waveform into squares at the other. The extreme end, when combined with wave ‘animation’, either from external CV modulation or by hand-sweeping the pot, gives very curious PWM effects – it in effect turns the module into a complex square wave VCO – and that CV input

is remappable too, so we can either CV control this Bitcrush amount, or have a second FM Input for more wobble, or CV-bank-select as we’ve seen, or most nicely of all, it can act as a ‘virtual VCA’, following envelope generator and LFO outputs (up to rates of around 1kHz), and so saving us the need for a VCA to control its level.

Asking designer Girts Ozolins from Erica Synths about the thoughts behind the design, their intention was to make something that was compact and with, in their words, “sound pressure”… and it feels like they did just that. There does seem to be a fundamentally solid and ballsy tone at play here – ‘beef’, for want of a better term, which is especially evident when you engage the Sub Octave generator. The ‘traditional’ waveforms could easily be mistaken for an analogue VCO in a mix; only at the highest registers do the warbles of digital aliasing give it away.

That Sub Octave generator needs to be mixed in externally, and has three modes – a copy of the current waveform minus one or two octaves, or a square wave minus one octave. There’s some voodoo going on here as the Sub octave generator isn’t locked in phase with the primary one; it intentionally drifts slowly, adding a lovely growling purr as these two waveforms play against one another. The square waveform isn’t ‘perfect’ either; it’s a little rounded off, with a spot-on fullness and warmth that just completes the voice, so that the two outputs in combination made us note adjectives like ‘classic, weighty and meaty’ – which is not to say that other wavetable VCOs sound bad, but that this one really does sound very, very good. It’s now one of the most affordable and compact wavetable VCOs in the format, with both digital modern wildness and synth tradition being well represented.