- Molten tube warmth makes this Erica system a sonic force of nature.
- Vacuum tubes aren't something you'd usually associate with modular synthesis. The fast paced, forward-thinking approach championed by the Eurorack movement seems a little at odds with the warm, traditional images conjured up by tube amplification. So what happens if you combine the two? Latvia's Erica Synths has been answering that question for a little while now, building a range of valve-equipped Fusion modules that mix tube warmth with rock-solid modular gear.
Basing an all-in-one modular system around the concept of drone creation is fairly novel. Modulars have an increasingly unfounded reputation for being the preserve of bleep and bloop enthusiasts, thanks to their use of wiggy sequencers, clock dividers and modulators. The Fusion Drone System, on the face of it at least, is more dour and simplified in its approach. There's no sequencer in the traditional sense, so any sort of solid rhythmic impetus has to be provided by external sources. Otherwise, you'll need to set the two modulators to work and ping CV signals around the system. This is a more chaotic and unpredictable approach, which seems to be exactly what Erica Synths would approve of.
The Fusion Drone System reviewed here is an expansion of the original first released back in 2016. Although it loses a couple of the little 3HP PICO VCOs, it gains an updated version of their Fusion VCF, the Fusion VCA, a two-in eight-out mult and the Black Series Modulator and EG modules. The choice and configuration of modules makes a lot of sense. In many ways, this system would be ideal for those looking to understand the basics of synthesis—and I mean synthesis in general, not just the modular kind. It's laid out logically, following the traditional synthesiser signal flow from left to right across the system. There's a simple rule to follow that helps get your head around the concept: tube-based Fusion modules control the audio, while the Black Series modules work as modulation sources.
Despite being on the far left of the system, the Fusion VCO is the centrepiece. It's powerful VCO is smooth, clean and deep sounding when it wants to be. But dial in the tube-saturated low-end and mess around with the waveshape knob and things take a dark and noisy turn. Modulating the waveshape with a slow sine wave LFO from the Black Modulator is probably the easiest way to get some movement into your patch. Modulating the pulse-width of the square wave sounds particularly naughty. A host of useful ins and outs means its presence is felt in a number of ways across the system, particularly through its FM input. Feed it an audio or modulation source to obtain everything from classic, metallic-sounding FM tones to weirder, more obtuse business. The Fusion VCO's double triode vacuum tubes work as sub-oscillators, creating pitches an octave and two octaves below the digital VCO. It's also possible to route in an external audio source, which bypasses the internal VCO. This could be anything from another VCO to a drum loop or hardware synth. The tube subs will still track the fundamental pitch of the incoming audio, beefing up and fleshing out the signal considerably.
The Ring Modulator is a pretty simple piece of kit that nevertheless does quite a lot. Despite what the manual says, I found it impossible to get a completely clean signal passing through it. But to be honest, clean isn't really the point. Audio is fed directly into the tube circuit, picking up plenty of high-end grit along the way, though you do sacrifice some low-end in the process. For me, the best way to use this module would be as a sort of effects send. You could run a cable straight from the VCO to an input on the VCF, then connect the VCF's Mix Out to the Ring Modulator's input, before bringing that output into a second channel of the VCF. This way you have the clean signal from the VCO on one channel, and a wet signal from the Ring Modulator on the other, which can then be blended to taste. A switch allows you to flick between lighter and darker flavours of ring modding (cutely defined by sun and moon pictograms), while the obligatory carrier input allows further modulation from any signal within or outside to the system.
Next in line, the Fusion VCF is a two- or four-pole low-pass filter. The tube's role here is to drive the signal between the filter's second and third stages. There's volume compensation built in to the resonance circuit to stop things getting out of hand, which it invariably tends to do. The filter resonance tends to spike quite aggressively around the one or two o'clock position, before the very harshest frequencies start being reduced. This being the second version of the filter, it gains an additional output compared to its predecessor. This means it's possible to feed the filter back into itself, which is handy for working with signals in parallel.
The Black Modulator spits out LFO or audio-rate modulation via its sine, triangle, pulse or sample & hold outputs (or all four at once), as well as four flavours of noise. The Black EG works as an ADSR envelope generator and features an inverted output and a looping AR mode, allowing for much quicker modulation cycles. Last in line is the Fusion Delay Flanger Vintage Ensemble. Switchable between long and short delay modes, it works as a bucket brigade type at the former setting and a tight, metallic flanger at the latter, but it's possible to find a number of pleasing sweet spots in between. The Colour knob acts as a low-pass filter, while an internally patched LFO is controllable with the CV Level knob.
If there's one way in which tubes and modular gear are related, it's cost. Eurorack is a well known burner of wallets (there's a reason some people call it Eurocrack). Tube amplifiers, meanwhile, are almost exclusively Not Cheap. You save a little money here by buying the Fusion Drone System compared to purchasing the modules individually, but more importantly, it's all ready to go right out the box. The 104HP skiff, power supply and copious amounts of patch cables are all essential items you'll need to get those modules in some sort of working order, and that alone will appeal to those wanting to dip their toes in the modular world. And while some may lament the lack of built-in sequencing options, the pure sound of the thing should more than make up for it.
Ratings:
Cost: 3.8
Versatility: 4.0
Ease of use: 3.7
Sound: 4.3