Is a valve modular system just a gimmick, or could it really offer something unique? Greg Scarth puts the Erica Fusion system to the test to find out.

In the early days of electronic music, all synths were modular and all modular synths had a distinct character.

Although in theory it was possible for certain manufacturers’ modules to work alongside each other, the emphasis was more on complete systems. If you wanted a Moog modular, you bought a complete Moog setup then maybe added a few modules to it later. If you wanted Buchla, you bought a complete Buchla system. If you wanted to go Japanese, you bought a Roland System 100m or 700…

There are, of course, a few companies who will offer you complete Eurorack systems today – notably Eurorack pioneers Doepfer, whose extensive range of modules encompasses almost everything you can imagine from the most basic LFOs, mults and mixers through to complex sequencers, VCOs and filters. What’s different is that very few of today’s companies offer the same kind of distinctive character you would have got from the varied modular synths of days gone by. That’s no sleight on companies like Doepfer, whose A-100 system is a hugely capable and versatile instrument, but it shows the way the market has changed.

Erica Synths are one of a handful of modular manufacturers who understand the value of philosophies, systems and design methodologies

Back in the 60s, modular synth design was as much about philosophy as it was about sound. On the east coast of the USA, Bob Moog’s instruments were all about offering the benefits of subtractive synthesis to keyboard players. By contrast, over on the west coast, Don Buchla largely eschewed keyboards, focusing on experimental sounds created using different synthesis methods (additive, wave shaping, FM…) and triggered by sequencers rather than keyboards.

There are plenty of Eurorack manufacturers today who follow a philosophy of sorts, but Erica Synths are one of a handful of modular manufacturers – alongside the likes of Make Noise and Bastl Instruments – who understand the value of philosophies, systems and design methodologies. The Latvian company regularly releases products in batches, built around a specific theme: the Polivoks modules based around the classic Soviet monosynth; the Pico system with its focus on using minimal rack space; the Fusion system we’re focusing on here, all based around valves.

When I first heard about the valve-based Fusion series from Erica Synths, I was interested to find out two things: firstly whether the valve circuits bring anything good to the table in terms of sound, and secondly whether the system works as a cohesive instrument in its own right.

Erica will sell you the modules from the Fusion range separately or as a €1,960 Fusion Drone System (both of which will interact perfectly well with any other Eurorack modules) but our test setup was rigged up as shown in the video above, with a few of the company’s Pico modules to link them together. From the Fusion range, we have VCO, ring mod, VCF and delay/flanger/vintage ensemble module. Alongside them are an additional Pico VCO (which doubles as an LFO), envelope generator, VCA and output section. Erica also make Fusion VCA and mixer modules, which take up much more space than the Pico equivalents but could be incorporated into a larger system.

A lot of cheaper valve gear relies on the valve as little more than a gimmick, tagging it onto a solid-state circuit as a final distortion stage to warm up the signal. It’s good to see that that’s definitely not the case here: each of the Erica valve modules is truly built around the valve itself. The Fusion VCO is based around a digital oscillator with valve-based sub-oscillators generated by two 12AX7 dual triode valves in “bistable latch connection”. The ring mod is based around germanium diodes with valves for wave shaping. The VCF uses a common twin-T bandpass circuit with the valve acting as pre-amp and feedback driver. The delay/flanger/vintage ensemble module uses bucket brigade chips with tube overdrive in the delay output and feedback path.

The VCO is a surprisingly blunt instrument for a digital oscillator, with a coarse tuning knob that spans the octaves, and no fine-tuning knob to get things precisely in tune. Nevertheless, it tracks precisely once you’ve got the tuning right and sounds suitably aggressive for powerful bass sounds. The sub oscillators are big and round, and can be made edgier using the colour control (marked with a moon at the anti-clockwise position and a sun at the clockwise setting). The ring mod is seductively grimy on its own but frankly it’s a bit unnecessary in the broader context of this setup, with plenty of other options to add harmonics and grit to the sound. The filter is unashamedly raw, with a pleasingly musical tone at low resonance, quickly turning filthy and self oscillating as the resonance is cranked up. The delay/flanger is harder to get to grips with, requiring a fine balance between the various controls to coax out different effects. The level of valve overdrive on the input is particularly sensitive here, with higher drive easily provoking endless drones at higher feedback settings.

The idea of valve synth circuits isn’t by any means new, but it’s still definitely unusual. The iconic early modular synths – Moog, Buchla, Serge, et al. – were based around solid-state technology (transistors, integrated circuits and the like), perhaps wisely eschewing the soon-to-be-near-obsolete valve technology. As such, there isn’t really a common reference point here in terms of iconic circuits or distinctive sounds, but the sound is impressive either way. Overall, the best way I can describe the modules is that they sound naughty. It’s a rough and ready sound with a similarly imprecise approach to dialling in many of the controls, far removed from something like the straightforward accuracy of a Doepfer setup or the mathematical complexity of Make Noise modules. Each one of the Fusion series contributes something interesting in its own right, but if I had to pick just one I’d be tempted by the delay/flanger module, which is capable of everything from basic delays to full-fat valve distortion and twisted modulation.

Would I build a setup around valve modules? I was expecting to say no, but having spent time with the Fusion setup I’m surprised to say I actually would. It’s distinctive, it’s versatile, but more importantly it’s fun. Music has always been about philosophies and aesthetic choices; Erica understand that and offer something fantastically different with the Fusion series. These are not sterile, surgical tools. Far from it. And they’re all the better for that.

Author Greg Scarth
8th November, 2017

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