SoftPop 2

Softpop SP2 + BITWIG 8-Track

Casper x Bastl

Softpop SP2 is a unique instrument and a complete rework of the original 2017 CASPERxBASTL Softpop. 

Softpop SP2 is a radical subtractive synth under the influence of unconventional digital control. It’s a rare beast excelling at both melody and noise in equal measure, ranging from bassline bangers, angelic chord progressions, distorted beats to water droplets.

Softpop’s patchbay is eurorack compatible, with the capability of processing inbound audio through the filter and VCA.

Softpop features a 16-pin eurorack power header inside the enclosure (requires +5V in the bus-board). 

Now with a free BITWIG Studio 8-Track license.

See the product page for instructions/downloadable content.

- More details in the Description below. -

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Softpop SP2 is a radical subtractive synth under the influence of unconventional digital control. It’s a rare beast that excels at both melody and noise in equal measure.  

SP2’s favorite sounds include bassline bangers, angelic chord progressions, distorted beats, and water droplets. Softpop also has an external input with enough gain and saturation to process any sound thru the filter and VCA.


The heart of SP2 is an analog, modular synth replete with lush tones and a chaotic disposition. Its brain is a complex digital sequencer and quantizer that brings (some) order to the chaos. The analog heart and the digital brain support each other while also pushing their behaviors out of normal routines in surprising ways. 


SP2’s sequencer is built around simple 8-step loops of notes, gates, and slides called PATTERNS. These PATTERNS (8 per BANK) can be played and chained in any order (and in real-time) to create longer sequences. Softpop's sequencer expands on this classic format by adding 8 SCALES of user-definable quantization, 8 playback modes, and 8 performance FX, all of which can be independently chained and looped!

Use the SCALE chaining to build chord progressions or reach for playback modes to browse the 8 steps in different ways. Add randomness and modulation to the pitch with the PITCH MOD fader and transpose the sequence with the PITCH fader. Temporary FX can be played on the fly to help you build transitions or looped for yet another degree of sequenced complexity. 


Plug any external audio signal into the SP2 to radically transform its sound with the built-in filter, VCA, and overdrive. Create stepped modulation with the sequencer and auto-wah style effects with the input-tracking envelope follower. Randomize it all with the sample & hold and use the 37-point patchbay to dive into the modulation madness. 

Here are a few possibilities for SP2 signal processing: 

modulated overdrive, stepped filter, auto-filter (auto-wah), random filter, audio-rate modulated filter, resonant distortion, feedback distortion, MIDI-synced slicer, sequenced ring-modulator, MIDI-controlled ring-modulator, compressor/expander, and plenty more to be discovered.


Softpop has a unique voice that reaches beyond classic subtractive timbres. It is playable by MIDI, and for all the sequencing fun, it features a quantizer with 8 user-definable SCALEs that can also be set by MIDI. SP2’s analog triangle core VCO has a built-in automatic digital tuning feature so that your melodies will be in tune in all octaves in just a few seconds. 


Eurorack compatibility, analog sync, and MIDI connectivity make the SP2 a mighty collaborator when combined with other instruments. USB power makes Softpop ideal for battery-powered setups, while its immediate fader interface is superbly suited for performance situations. Like any real instrument, Softpop provides a lot of depth accessible by button combinations. These are described on the enclosure so you won’t get sucked into your phone while searching for the manual.


Softpop is the culmination of a near decade-long creative partnership between Casper Electronics and Bastl Instruments and brings together the strengths and quirky design stylings of lead engineers Peter Edwards and Václav Peloušek. We feel it’s our best work to date and a product of pure passion for innovative synthesis, music-making, and experimentation. There are a few things very unique to Softpop that you will not find anywhere else. For instance the super pingable filter with the POP cross-modulation, the quantizer chaining, the playback modes, and their chaining or the MIDI-controlled quantizer. 

The Softpop SP2 DNA comes from the original SoftPop, a unique art object inspired by a cult-classic synth called the Benjolin designed by Dutch synth genius Rob Hordijk. The primary locus of inspiration from the Benjolin was the intricate interplay of the controls that create sonic behaviors more akin to a creature you can befriend than a studio tool you can control. 


  • Fully analog signal path with integrated digital control
  • Patchbay with 37 eurorack compatible patch-points for ultra-flexibility
  • Light orb for psychedelic inspiration
  • Triangle core oscillator with PWM input and pulse and triangle outputs
  • Automatic oscillator tuning and octave-wide fine-tune control
  • Quantized V/OCT semitone transpose
  • State variable resonant filter with lowpass, bandpass, and highpass modes
  • POP control for unique subtle and distorted timbres
  • Flexible attack-decay cycling Envelope with a ton of control inputs

  • Drone or envelope mode switch for the VCA
  • Musical sequencer with a lot of tricks
  • 8 step sequencer with pattern chaining to extend the length
  • Sequenceable scale quantizer with 8 user-editable scales
  • 8 patterns per bank, 8 banks (saved on demand)
  • Envelope gates per step
  • Slide option per step for that acid feel
  • Playback modes will turn your simple patterns on their head
  • Temporary FX section (ratchets, arps, noise, and more)
  • CV, gate, and clock outputs from the sequencer
  • External input for processing audio with dynamics analyzer 
  • Analog sync Input
  • Tempo section with divider/multiplier
  • MIDI input for sync and musical control
  • XY crossfader utility section and 4-way multiple for advanced patches


SP2 has officially leveled up. This free firmware update (present in all units shipped after 09/2022) unlocks enhanced MIDI control, MIDI CC implementation, new CV and GATE output modes, and a bunch of quality-of-life improvements. But the real big news is that the original analog oscillator (bless its pitch-drifting soul) has gone digital. That means vastly improved tuning precision and stability and 8 new variable waveforms to explore and run through SP2's rich and unruly analog filter and VCA.

Detailed description of all new features in the digital VCO upgrade manual. This update requires moving a jumper on the SP2 circuit board before uploading the new firmware. Files and upgrade manual available on the product page.


  • Digital VCO
  • Fine-tune fader mode
  • ENV G and SLIDE G trigger/gate modes
  • Envelope gate probability as FX8
  • Triggered pitch change mode
  • VCO Pitch Limiter
  • CV pitch tracking mode
  • MIDI clock detection
  • FX controlled by MIDI notes
  • Envelope triggered by Note On mode
  • MIDI CC implementation
  • MIDI transpose
  • Improvements and bug fixes
  • New button combos

Adaptors for mounting Softpop SP2 to eurorack rails are available as open-source files or sold here


  • Softpop SP2
  • Quickstart guide
  • 5 patch cables (15cm: Green, Dark Green, Brown, Black and White)
  • Micro USB cable (excl. power supply)
  • Rubber feet
  • Sticker 


  • USB power (micro): <250mA
  • Dimensions: 173 x 112 x 41 mm
  • Inputs are capable of receiving eurorack signals
  • 16 pin protected eurorack power connector requires 5V from busboard: <250mA
  • Eurorack size rail adaptors available as open-source files
  • All outputs are 5Vpp except for: PULSE, EDGE, ENV, BP, and DYNAMICS that are 4Vpp


See the product page for instructions/downloadable content.


Data sheet


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