Zorx Electronics
Sofia  -Xaoc Devices

Sofia -Xaoc Devices

by Jason Czyeryk

Superbooth 2022 was an interesting affair. Still heavily impacted by the pandemic, there was less traffic, both in terms of manufacturers and attendees; however, that in no way meant a dearth of interesting and exciting synths and modules being shown there. All of the new modules that Xaoc Devices presented were GAS-inducing, but Sofia, their new all analog VCO, was the one I had anticipated the most.
Sofia is based on a unique waveforming idea that centers around a core oscillator with two waveshaping sections called “ripple elements” that use time-domain components like density and decay to modulate the main core oscillator. According to Xaoc, this is a method employed by computer music that’s called FOF [fonction d'onde formantique], a technique to create formant sounds, one that I’d never encountered before.
Every new cycle of the base tone creates a new pair of ripple elements, kind of like a pair of sidekick oscillators that interact with and contribute to the overall sound and changing of the main oscillator. The way Sofia operates is similar in some ways to a more traditional complex oscillator, but it’s got three oscillating elements instead of the usual two.
Sofia is a great looking module with sliders and knobs of various sizes and shapes. It’s got an intuitive layout with the MAIN oscillator’s controls running down the center of the module and with each of the ripple element sections [A and B] on both sides. The main section consists of a large PITCH knob, which sports a two-octave span, situated below a chicken head pointer knob for selecting the OCTAVE, that has an eight-octave range, one of those being an LFO. There’s a PITCH CV V/OCT input to control the PITCH of the MAIN sine wave oscillator with external CV, and PITCH FM and GLOBAL FM inputs, both with attenuators. At the bottom are MAIN and FUNDAMENTAL outputs. On the left side of the OCTAVE knob is the ELEMENT MIX, which controls the mix between elements A and B—with the center position being equally mixed between the two ripple channels—that affect the MAIN oscillator. On the right of the OCTAVE control is the FUNDAMENTAL ELEMENT MIX, which determines how much the output of the ELEMENT MIX affects the MAIN oscillator. Fully CCW and you only hear the MAIN oscillator at the MAIN output, and fully CW and you only hear the mix of the ripples—no MAIN oscillator to be found. With a center position on both mix controls you will get an even mix of both the A and B ripples affecting the core oscillator, along with an even mix of the unaffected core oscillator and the ripple-affected core at the MAIN output.
Both ripple element sections are similarly laid out with controls for WARP and RATIO [both with CV inputs] and a DAMP CV input. RATIO and DAMP utilize light up slider attenuators for honing in on the desired amount. The RATIO controls how compacted the ripples are in relation to the fundamental tone, while the DAMP controls the decay rates of the ripples. The WARP control changes the ripples uniformity through each fundamental cycle of the wave.
Each element section also has a small switch to choose the core shape of the ripple for either a sine or square wave and switches for the RATIO and DAMP that determine whether or not those parameters are related to the fundamental period of the core oscillator, and if the ripple tracks the pitch or not. Each ripple element also has a pair of outputs: IMPULSE and A or B OUT. The IMPULSE outs give you the decay curve for each of the ripple elements to use for modulation, while the A or B outputs give you exactly what they advertise; the output of either ripple. One of the unique features of Sofia is that even though the MAIN output can look like all sorts of craziness, that it can have what seems to be a chaotic frequency cache, the frequencies are in fact all harmonically related, which is one of the ways Sofia is not like a traditional complex oscillator.
I won’t lie; it took me several passes through the manual to get a somewhat decent grasp of Sofia’s features. It’s not complicated in theory so much as I just didn’t grasp the relationship [and functionality] of the WARP, RATIO, and DAMP functions right off the bat. Nonetheless, the studiousness I undertook to get a hold on Sofia was worth it. Even at its most basic, manipulating one of the ripples to hear the sounds Sofia can conjure up internally, was rewarding, with wonderful tones emanating from it. It’s a superb sounding module and can/does have a metallic formant aesthetic, almost like a nasally filter sweep, which actually sounds way cooler than my description. Modulating the RATIO with any kind of LFO and you can hear Sofia whispering a hostile robot-y takeover ever so sweetly and with a smooth modulator this formant slant is really pronounced. Messing with the switches, with RATIO and DAMP in the off position, a square wave for the ripple [only working with A here], and an even mix of the A ripple and the core oscillator at the MAIN output, and the sequenced melody I had going sounded absolutely beautiful, one of the best oscillators I’ve ever heard. I put a little reverb on it and added some slow moving out of sync LFOs to the RATIO and DAMP and did some self-patching from IMPULSE B to the WARP A input, and remained really impressed.
Utilizing more complex modulation and teaming Sofia with Xaoc’s excellent Koszalin frequency shifter [reviewed in Waveform, #9] and the Worng Parallax filter, and doing some cross modulation, the resulting output became more predictably complex, more complicated. Whistling howling winds, bouncing ball fizzles, un-namable bonkersness, I got lost many times within the modulation. It’s such a great sounding module, I realized I didn’t want to obfuscate its beauty, only to enhance it to where I felt that having a light touch was best. Sofia can get nasty with the best of them, but there are plenty of modules in my rack that can get nasty, with very few of them that can sound as elegant and pleasing as Sofia. Let those other oscillators and sound sources run through various distortions, manglers, and souped up filters, Sofia needs none of that.

24 HP +12v 90mA -12v 80mA
Price: $490