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.

Heart and Brain

The heart of SP2 is a 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 heart and the brain support each other while also pushing their behaviors out of normal routines in surprising ways.

Beyond 8 steps

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.

Softpop SP2 is a powerful sound processor!

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.

Tonality

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 digital VCO makes sure your melodies will be in tune in all octaves.

Connectivity, portability

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.

CASPERxBASTL

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.

Raving reviews

• Bastl Instruments Softpop SP2: A tiny terror, ten years in the making - a review by MusicTech
• Softpop SP2 selected as Eurorack Gear of 2022 by Orb Mag
• Softpop SP2 listed as Best hardware experimental Synthesizer releases 2022 by Synth Anatomy
• Casper Bastl Softpop SP2, portable experimental analog synth with an organic touch - a review by Synth Anatomy
• Bastl/Casper Electronics Softpop SPII im Test - a test/review by Sound&Recording

Features

• Modular synth with integrated digital control
• Patchbay with 37 eurorack compatible patch-points for ultra-flexibility
• Light orb for psychedelic inspiration
  
  
• Digital oscillator with several waveforms and waveshaping (alternatively legacy triangle core oscillator with PWM input and pulse and triangle outputs)
• Automatic oscillator tuning and octave-wide fine-tune control (for analog VCO)
• 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
  
  
• 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

SOFTPOP SP2 DIGITAL VCO UPDATE v1.3 (07/2025)

Softpop SP2 just got sharper. The v1.3 firmware update brings tighter sync, smoother MIDI response, and a brand new direct step editing workflow that makes sequencing feel more immediate and intuitive—whether you’re playing or stopped. You can now record GATEs directly, preview pitch while editing, and enjoy better stability with external clocks and MIDI input.

We also squashed a few bugs, improved filtering on CV inputs, and added quality-of-life updates like autosaving triggered pitch mode and better handling of RESET signals.

Important: If updating from the analog VCO version firmware (units manufactured pre-09/2022), this update requires switching to the DIGITAL oscillator via the onboard jumper before installing the new firmware. All update files and a full upgrade manual are in the Downloads section.

New features include

• TRIG/GATE recording: record gate events by pressing TRIG while holding REC
• Direct step editing: edit steps live or while stopped, with pitch quantization to scale
• Step pitch preview: hold step + press TEMPO to hear the note with envelope trigger

Tutorials

• Firmware update video manual
• Softpop SP2 short documentary with Peter Edwards / Casper Electronics
• All BASTL SOFTPOP SP2 tutorials in one playlist

What’s in the box

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

Technical details

• power: 5V via Micro USB
• power consumption: <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

Downloads

• quickstart guide pdf
• complete manual pdf
  
  
• patch sheet A4 pdf
• eurorack adaptor file gitHub
  
  
• press release pdf
• media files (hi-res pictures, wallpapers etc.) drive
• FAQ

Latest Digital VCO firmware v1.3

• latest digital VCO firmware v1.3 (07/2025) wav zip
• firmware update manual pdf video

Legacy Analog VCO firmware

All units from the batch shipped in February 2022 have version v1.1 installed. Please update to v1.2 for better sync stability (or you can switch to the digital VCO).

• complete manual for analog VCO SP2 pdf
• last analog VCO firmware v1.2 (03/2022) wav
• release notes & how to update to v1.2 pdf

Audio

Video