⚡️ The 30-Second Takeaway
The Pitch: A “Turbo Plaits” for iOS. Oliver Greschke takes the legendary 24-engine hardware module and supercharges it with 8-voice polyphony and recorded X/Y touch automation.
- The Hook: Hardware-grade DSP with “elastic” modulation you won’t find in Eurorack.
- Killer Feature: Import DX7 banks directly into the 6-op FM engines.
- The Damage: $14.99 (Core) + $3.99 for the Pro LFO pack.
- Verdict: Essential. It’s a massive studio’s worth of synthesis for the price of a lunch.
A bit of backstory: In 2014, when Oliver Greschke and Mouse on Mars dropped Elastic Drums on iOS, it changed what we expected from mobile music production. Fast-forward to May 2025, and Greschke has done it again with Elastic OSC—a synthesizer app that takes the legendary Mutable Instruments Plaits oscillator module and transforms it into a fully playable, polyphonic instrument for iPhone and iPad. What makes this special is how Greschke reimagined Emilie Gillet’s brilliant macro-oscillator design for touch-based performance rather than just porting the module.
What Is Elastic OSC?
Elastic OSC is a synthesizer app built around the DSP code from Mutable Instruments Plaits, one of the most beloved and cloned oscillator modules in the Eurorack modular world. While the hardware Plaits gave you 24 different synthesis engines in a compact 12HP module, Elastic OSC adds something the hardware could never offer: 8-voice polyphony, X/Y pad control for intuitive sound manipulation, and a complete effects chain—all optimized for touch-based performance.
The app works as both a standalone iOS instrument and an AUv3 plugin, integrating seamlessly with hosts like AUM, Cubasis, and Logic Pro for iPad. Desktop versions for Mac and Windows (AU and VST3) are planned for future release.
The Plaits Legacy
To understand what makes Elastic OSC special, you need to know about its source material. Mutable Instruments Plaits was essentially a complete synth voice in a single module, featuring a built-in modulation source and low-pass gate. The original MIT-licensed DSP code (created by Emilie Gillet) offered 16 synthesis modes at launch, expanding to 24 with the version 1.2 update. All 24 modes are reproduced in Elastic OSC, accessible via numbered buttons at the top of the screen.
Think of Plaits as a sonic Swiss Army knife. You get classic virtual analog oscillators, 2-op and 6-op FM synthesis, wavetable and additive synthesis, physical modeling (Karplus-Strong strings, modal resonators), granular clouds, speech synthesis algorithms, percussive sounds (kicks, snares, hi-hats), and even chiptune engines. Each mode has its own character, and the variety is staggering.
Perhaps I’m looking back with nostalgia, but when Plaits first appeared in the modular world, it felt like having access to an entire studio’s worth of sound sources in 12HP of panel space. Oliver Greschke has captured that same magic and made it genuinely playable.
The Elastic Difference
What separates Elastic OSC from other Plaits implementations—like the versions in VCV Rack, miRack, or Surge XT—is its focus on playability and touch-based performance.
Color-Coded X/Y Pads
The app’s defining feature is its elegant dual X/Y pad system. The left pad controls four core synthesis parameters (Frequency, Harmonics, Morph, and Harmo), which change behavior depending on which of the 24 engines you’ve selected. You can even swap which parameters appear on each axis, tailoring the interface to your workflow. The right pad provides direct control over the built-in effects chain.
These pads are genuine performance tools. You can record modulation and automation on almost any parameter with lengths of 1, 2, or 4 beats, then loop those movements in sync with your tempo. It’s the same “elastic” automation philosophy that made Elastic Drums so addictive, now applied to melodic synthesis.
Mono and Poly Modes
Hardware Plaits is strictly monophonic. If you wanted polyphony, you’d need multiple modules and a lot of patch cables. Elastic OSC gives you an 8-voice polyphonic mode with the tap of a button. This transforms the app from an experimental modular-style oscillator into a fully functional keyboard instrument capable of pads, chords, and complex harmonic textures.
For voice modes, you get both the original’s Low Pass Gate (LPG) envelope for modulating timbre, FM, and harmonics, plus a traditional ADSR envelope for amplitude control. The ADSR acts as a VCA at the end of the signal chain, so you’ll need to increase the LPG decay first to hear it work. For percussion engines, the ADSR is automatically disabled—a smart design choice.
Major Updates That Changed Everything
The DX7 Connection
In September 2025, version 1.1 added something unexpected: the ability to import DX7 banks into the three 6-operator FM engines (modes 19-21). This opens up decades of classic FM synthesis presets to iOS users. The harmonics slider was refined to 32 steps for these engines, reflecting DX7 preset switches, and the envelope behavior was improved to more accurately match the original hardware sound.
Needless to say, this turned Elastic OSC into a portal for endless DX7 sounds. 😳
The LFO Update
December 2025 brought version 1.2, and with it came the long-awaited LFO support. This is a game-changer for anyone who felt Elastic OSC needed deeper modulation options. The update includes one free LFO, with three additional LFOs available as an in-app purchase for $3.99 USD.
Each LFO is remarkably sophisticated, offering frequency control from 0.02 to 20,000 Hz (or tempo-synced), six waveform shapes (sine, triangle, ramp up, ramp down, pulse, and sample & hold), fade-in time, phase control, and three trigger modes: Retrigger (restarts with each note), One Shot (plays a single cycle when triggered), and Free (runs continuously without retriggering).
FYI: The LFOs integrate beautifully with the X/Y pad system. You can use the pad to control frequency and shape, and even record modulation of those parameters—essentially creating modulation of modulation. That’s proper modular thinking.
The LFO section provides six modulation targets that Greschke describes as having “the greatest impact”: Frequency, Timbre, Morph, Harmonics, Filter, and Pan. All amount knobs can themselves be modulated and recorded, enabling dynamic changes of modulation depth over time.
When you have multiple LFOs active, the MIX view lets you define how strongly each one affects a target parameter. The closer a target is placed to an LFO in the visual mixer, the stronger its influence. All active LFOs always add up to 100%, so if you have LFO1 at 50%, LFO2 at 30%, and LFO3 at 20%, they’ll proportionally affect the selected target.
The 1.2 update also made the filter polyphonic (a major improvement), added new presets from sound designers Servando and Another Machines, improved slider displays to show values like knobs do, and squashed various bugs including issues with Drambo integration and unwanted buzzing in the Wave Terrain engine.
Sound Engines Breakdown
All 24 synthesis modes from Plaits are present, organized into pitched sounds, noise/percussion, and experimental sources:
Classic Synthesis
- Two detuned virtual analog oscillators
- Waveshaping triangle oscillator
- 2-operator FM
- 24-harmonic additive synthesis
- Wavetable (four banks of 8×8 waves)
- Chord generator (wavetables or vintage organ-style divide-down)
- Phase distortion
- Three variants of 6-operator FM
- Wave terrain synthesis
- String machine emulation
- Virtual analog VCF (voltage-controlled filter)
Experimental & Physical Modeling
- Granular formants
- Speech synthesis algorithms
- Granular cloud (saw or sine wave-based)
- Karplus-Strong string modeling
- Modal resonator
- Chiptune synthesis (this one’s a personal favorite)
Percussive Engines
- Two analog kick models
- Two analog snare models
- Two analog hi-hat models
- Clocked noise + filter
- Dust/particle noise + filters
Each engine has its own sweet spots. The granular modes excel at evolving textures. The FM modes—especially with DX7 banks loaded—deliver everything from glassy bells to aggressive bass. The physical modeling engines (strings, modal resonator) respond beautifully to velocity and articulation.
The A/B Output Trick
Here’s something that often gets overlooked: Plaits (and by extension, Elastic OSC) offers two outputs. Output A is your main signal, but Output B delivers an “aux” signal that’s a “variant, sidekick, or by-product” of the main signal. What that means depends on which engine you’ve selected.
Sometimes it’s a sub-oscillator. Sometimes it’s a bitcrushed version of the main signal. In certain modes, panning A hard left and B hard right gives you a pseudo-stereo effect. You can also blend A and B together or mix them with hard panning. This effectively doubles your sonic options beyond the 24 engines, creating hybrid variations that aren’t possible with just the A output alone.
Do yourself a favour and experiment with the A/B output mixer. It’s one of those features that seems simple but opens up a world of creative possibilities.
Master Effects Chain
Oliver Greschke confirms that the effects in Elastic OSC are all-new code, distinct from what appeared in his earlier Elastic FX app. The processing chain includes:
- Distortion: Six modes (sine, bitcrusher, downsampler, asymmetrical, pow2, tanh2) coded by Lucie Gosset
- Filter: High/low filter with resonance
- Modulation: Chorus/flanger with feedback control
- Delay: Synced or free-running with spread parameter
- Reverb: Time, damping, and spread controls
- Limiter: Switchable master limiter
These effects sound great and integrate seamlessly with the second X/Y pad. The distortion modes, in particular, add significant character—especially useful for thickening up the more digital-sounding engines like the chiptune and additive modes.
How Does It Sound?
Versatile and Deep
The sonic range is massive. You can dial in warm, analog-style pads from the detuned oscillator mode, then switch to aggressive FM bass stabs, then jump to ethereal granular clouds—all within the same app. The speech synthesis modes are wonderfully weird, perfect for sci-fi soundscapes or unsettling ambient textures. The percussion engines are punchy and characterful, though if you want a full-featured drum machine, you’re better off with Greschke’s Elastic Drums (which remains one of the best iOS drum synths available).
Organic and Playable
What impressed me most is how organic Elastic OSC feels in practice. The X/Y pads encourage exploration in a way that rows of knobs or sliders don’t. You find yourself making happy accidents, stumbling onto parameter combinations that wouldn’t have occurred to you otherwise. The modulation recording feature amplifies this—capture a moment of inspired tweaking, loop it, and build a track around it.
The polyphonic mode transforms the app entirely. Suddenly you’re not just playing with modular-style oscillator timbres; you’re playing a legitimate polysynth with character and depth. The way the LPG and ADSR envelopes interact gives you fine control over articulation, from plucky and percussive to slow and evolving.
With the LFO update, the sonic possibilities expanded exponentially. Now you can create slow-evolving pads with LFOs modulating harmonics and filter cutoff simultaneously, or aggressive sequences with multiple LFOs set to different tempos creating polyrhythmic modulation. The ability to use the polyphonic filter as a pseudo-envelope via LFO modulation is particularly clever.
Practical Tips
- Start with the help overlay. Tap the question mark icon to see detailed explanations of what each parameter does in the current engine mode. This helps you learn the quirks of each synthesis type.
- Use the A/B output creatively. Don’t just stick with Output A. Experiment with A+B blend and A/B hard-panned modes to discover hidden variations.
- Record modulation in short loops. One or two-beat automation loops can add subtle movement without overwhelming the sound. Save four-beat loops for more dramatic transformations.
- Experiment with LFO trigger modes. Free mode is great for drones and evolving pads, Retrigger creates percussive articulation, and One Shot can function like an additional envelope.
- Layer mono and poly instances. If your host supports it, try running two instances of Elastic OSC—one in mono mode for a lead or bass, another in poly mode for pads or chords.
- Increase LPG decay before using ADSR. The ADSR envelope won’t do much if the LPG is cutting off the sound too quickly. Set LPG decay to a higher value first, then shape the amplitude with the ADSR.
- Explore velocity settings. You can adjust how velocity affects volume and/or LPG modulation. Subtle velocity response makes the synth feel more expressive and natural.
- Import DX7 banks for instant inspiration. If you’re stuck for ideas, load a DX7 bank into one of the 6-op FM engines and cycle through presets. Even if you don’t use them as-is, they’re great starting points for further tweaking.
- Use the LFO MIX view strategically. When multiple LFOs are active, the visual mixer helps you understand which LFO is doing what. Start with one LFO per target, then gradually introduce complexity.
Pricing and Availability
Elastic OSC launched in May 2025 with an introductory price of $9.99 USD (regular price $14.99 USD). The core app now sits at $14.99 USD on the App Store, which includes one free LFO. The additional three LFOs can be unlocked via in-app purchase for $3.99 USD, bringing the total investment to under $19 for the complete package.
Even at full price, the value proposition here is exceptional for what you’re getting—24 synthesis engines, polyphony, effects, sophisticated LFO modulation, DX7 bank import, and that unique touch-based interface.
The app is available now for iOS (iPhone and iPad) as a standalone app and AUv3 plugin. Desktop versions for Mac and Windows (Audio Unit and VST3 formats) are planned for future release but have no confirmed date yet.
You can find Elastic OSC on the App Store or learn more at the MoMinstruments website.
Final Thoughts: Do You Need This?
All I can tell you is this: if you make music on iOS and you’re even remotely interested in synthesis beyond presets, Elastic OSC is essential. What Greschke has done here is take one of the best oscillator designs in modular synthesis, enhance it and make it playable on a touchscreen.
The X/Y pad interface feels natural in a way that knob-based interfaces don’t. The polyphonic mode opens up musical possibilities that hardware Plaits users can only dream about (unless they’re willing to buy eight modules). The automation recording turns sound design into performance. The LFO update transformed an already powerful synth into something that rivals desktop modular environments in terms of modulation depth.
How about you? Are you making modular-inspired music on iOS, or are you still skeptical about mobile synthesis? 🤔
If you’re coming from hardware modular and wondering whether Elastic OSC captures the spirit of Plaits, the answer is yes—and then some. If you’re new to synthesis and looking for an app that rewards exploration without overwhelming you with complexity, this is one of the best entry points available.
I spent an evening just tweaking those X/Y pads with some DX7 banks loaded, and three hours vanished. After the LFO update dropped, I lost another evening setting up polyrhythmic modulation patterns that I’d normally need a full Eurorack case to achieve. That’s rare with music apps these days. When an instrument makes you lose track of time like that, you know the developer got something right.
