Before you even turn it on, it's clear the softPop is going to be interesting. With six reasonably large faders dominating the controls, it looks more like a tiny DJ mixer than a modular synthesiser. Unfortunately, not every control has grown out of the tiny-fingered domain—other than the faders, all the synth's buttons and switches are small as ever. Saving space is still a priority here as several crucial controls like input gain and filter resonance are found not on the front panel but along the box's sides.
At its core, the softPop is a two-oscillator subtractive synth, albeit a pretty complex one. The two oscillators (VCO0 and VCO1) have identical controls on the far left and far right of the fader array. In each VCO group, one fader controls pitch while the other controls the modulation index. VCO0's modulation source is normalised to the patchbay's Track+Hold output (more on that later) while VCO1's mod source is normalised to a mix of its own inverted square wave output, VCO0's triangle output and the external input. VCO1 can also be switched from continuous cycling to a one-shot mode triggered by an impossibly small button. This button is my only real gripe with the softPop—it would have been really helpful if there was a way to trigger this with the patchbay.
VCO0 has a few extra controls of its own. First comes an autotune-style quantiser that converts its continuously variable pitch range to a stepped scale of chromatically tuned notes; then there's a pattern generator that records and loops the behaviour of the VCO's faders. Last but not least, it also has a humble but practical fine-tune thumbwheel with a range of five semitones. The quantiser and fine-tuner are useful and straightforward, but the pattern generator was a bit hard for me to wrap my head around. It seems to function like a shift register but I often had trouble figuring out if it was actually doing anything. However, it functions well as an extra voltage source available within the patchbay.
Between the two VCO controls lies the softPop's mighty multimode filter. The first fader controls cutoff and switches from low- to high-pass as you slide through the middle. The second fader controls modulation sourced from a mix of VCO0's square output and VC01's triangle wave. Below the front panel is a Walkman-style thumbwheel for the crucial resonance control. This is where the softPop earns its name: the filter becomes incredibly bubbly and feeds back beautifully without losing any low-end as the resonance goes up. Even if you aren't sold on the softPop's VCOs, its strength as an effects processor and filter for external signals is considerable, especially once you've taken advantage of the patchbay's envelope follower as a mod source for the filter cutoff.
Upon closer inspection, the patchbay reveals far deeper functionality than the minimal fader controls suggest. Each oscillator has a mod input that can be attenuated by the faders. There's also a CV input for additional full-strength modulation or 1 volt/octave pitch control. What's more, there's a sync input and outputs for each VCO's square and triangle waveforms. The filter has identical inputs for mod/CV signals as well as an external input socket. Once you get over the awkwardness of the patchbay's tiny sockets, you realise Bastl hasn't cut corners on functionality. For one, you get separate sockets for low-, band- and high-pass outputs. There's also an easily-overlooked aux input for patching signals directly to the output mix, skipping the filter in the process.
The bottom row of patch points deal with more practical and easily-missed functions. There's an output for the pattern generator's looping voltage sequences and a rather handy envelope follower, which is hardwired to follow the EXT output socket's signal. Next, there's a pair of unusual waveform outputs. The first contains a mix of (take a breath) VCO0's square wave, VCO1's triangle wave and the EXT input signals; the second is just a mix of VCO0 and VCO1's triangle waves. The manual suggests it's "especially useful for filter modulation," a statement that I fully agree with.
At the very bottom of the patchbay is the aforementioned Track+Hold section. As it makes a few appearances in the softPop's normalised signal path, it's worth mentioning that the input is normalised to the filter's bandpass output and is gated by VCO1's square wave. This means changing VCO1's pulse-width via the mod fader will give immediate and dramatic results without patching in a different gate signal.
Along the top edge of the softPop are three stereo minijack sockets, labeled A, B and C. These are mirrored in the patchbay as L/R socket pairs. They're also bi-directional, meaning you can use them to bring external CVs in from other gear or send audio and control voltages out from the softPop. This opens up really deep possibilities for integrating with a modular system and even more so if you notice the mysterious Secret Chamber (official name) hidden in the softPop's underbelly. The manual warns that this wood-shielded cavern is for "advanced users only," but anyone looking to use the softPop as a fully modular machine should feel free to slide those tiny doors aside and dig in. The important thing here for most users is the bank of six switches for breaking normalisation routings. Everything important is labeled on the PCB itself, but the Secret Chamber is also well-documented in the manual. There's also access to the pattern generator's microcontroller for the programming-inclined.
There's no lack of features to explore on the softPop. I haven't even mentioned the hypnotic, mood ring-like LED orb that makes even the simplest drone a fun audio-visual experience. This tiny, battery-powered box with a built-in speaker somehow rivals the Moog Mother-32 as a compact but feature-rich analogue synthesiser. The experimental approach to interface design lends itself to quickly devising gurgling drones, extreme leaky-faucet sounds, laser zaps and distorted random basslines. But taking advantage of the softPop's deep patchability reveals a terrific sounding (if sometimes harsh) synthesiser that can be much more than a noise set in a box. The black panel, fiddly switches and small buttons don't lend themselves to playing in a dark club. But as a sound design tool and out-there filter unit, the softPop packs a lot of bang for its buck.
Ease of use: 3.8