Comparison

SynthMaster 2 vs Audulus 4

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

SynthMaster 2

This powerful software synthesizer offers a vast array of sound design capabilities, including multiple oscillator modes, extensive modulation options, and a wide selection of filters. Explore over 1000 factory presets or create your own unique sounds. Available as a standalone app or AUv3 plugin.

Highlights
  • Multiple oscillator modes (Basic, Additive, Wavetable, Vector)
  • Extensive modulation architecture
  • 6 filter categories
  • Import custom wave files
  • 1000+ factory presets
  • Standalone app and AUv3 plugin
Read full description

KV331 Audio is proud to announce the availability of their award winning software synthesizer SynthMaster 2.9 on iOS platform. As being the first app developed using KV331 Audio’s new cross-platform UI framework, SynthMaster 2 runs as a standalone app or AUv3 plugin on iPads with iOS 11 and above. SynthMaster 2 supports native resolutions of various iPad devices. User interfaces are provided for 9.7, 11 and 12.9 inch iPads in 4 different skins (Blue, White, Dark, Proto). Separate interfaces are provided for the AudioUnit plugin as well. SynthMaster 2 comes with 1000 factory presets designed by world class sound designers such as BigTone, Nori Ubukata, NatLife and Yuli Yolo. Thanks to the comprehensive preset browsing features, users can easily filter presets by author name, bank name, instrument type or preset name and find the sounds that they are looking for. There’s also an IAP Shop, which lets users purchase additional sounds: 1. "Desktop Presets Upgrade": This IAP adds all factory presets in SynthMaster 2.9, increasing the total preset count to 2000. 2. "All Expansions Bundle": This IAP adds all current 38 SynthMaster preset expansion banks. Sound Engine: At the heart of SynthMaster 2’s powerful sound engine lies its oscillators, modulators, and filters. Oscillators: The oscillators can operate in 4 different modes to generate sound: 1. In Basic mode, the oscillator plays single cycle waveforms or samples. With the Oscillator Unison turned on, up to 8 voices per oscillator can be played. 2. In Additive mode, 8 Basic oscillators can be stacked up to create richer tones. 3. In Wavetable mode, the oscillator can play wavetables with up to 256 frames. 4. In Vector mode, 4 Basic oscillators are mixed in 2 dimensions. Modulators: Modulators are simply basic oscillators that can be added to other oscillators or modulate other oscillators’ or modulators’ phases. By connecting modulators to other oscillators or modulators, complex FM tones can be synthesized. Importing Wave Files into SynthMaster: While designing sounds, users can easily import wave files into SynthMaster 2. SynthMaster 2 can categorize those files into waveforms, wavetables or multi samples and import them accordingly. Filters: Once the sound is generated by the oscillators it goes through SynthMaster’s filters, which can operate in 6 different categories: Digital, VAnalog, Ladder, Diode Ladder, State Variable and Bite. Custom distortion can be applied before or after the filters as well. Modulation Architecture: SynthMaster 2 features a comprehensive modulation architecture with a wide range of modulation sources: 1. MIDI controls 2. Macros controls 3. 4 ADSR envelopes per layer 4. 4 Multisegmented envelopes per payer 5. 4 LFOs per layer 6. 4 Sequencers per layer 7. 4 Keyscalers per layer There’s real-time visual feedback that lets users see how modulation sources and targets are changing when a note is being played. This is extremely helpful when designing sounds with SynthMaster 2. New modulations can be created easily by dragging and dropping a modulation source onto a knob or slider control. Users can easily see which controls are modulated by a modulation source by clicking on that source. Controls that are being modulated by that source will display modulation amounts. By long pressing a control, the modulation amount can be edited without the need to go through the mod matrix. Arp/Sequencer: SynthMaster features a comprehensive arpeggiator / sequencer with 32 steps. Users can easily create sequences by recording steps one by one. Effects: Each of the 2 layers in SynthMaster has 5 insert effect slots. 13 different types of effects can be instantiated in any of those slots. There are also 2 global effect send busses which can be used to create more complex effect routings.

About

Audulus 4

Create and shape sounds with a professional-grade modular synthesizer environment. Explore a vast library of modules for synthesis and sound design, with the option to expand your toolkit with premium instruments and effects. Available across Apple devices for seamless workflow.

Highlights
  • Modular synthesizer environment
  • Sound design tools
  • Real-time audio shaping
  • Extensive module library
  • Premium Pro Modules (in-app purchases)
  • Cross-device iCloud sync
  • AUv3 plugin support
Features
Read full description

Build synthesizers. Design sounds. Shape audio in real time. All with professional-grade, low-latency performance ready for live use — and it’s free. Audulus gives you a complete modular environment at no cost. Its clean, fluid interface stays out of the way so you can focus on what matters: exploring sound. A modular playground with room to grow — from first experiments to advanced designs. Looking for more? Discover the Pro Module series: premium instruments and effects that show what’s possible when world-class sound design meets true modular freedom. Each Pro Module is crafted specifically for Audulus, giving you new ways to expand your sonic toolkit. Available on iPhone, iPad, and Mac — your modular system travels with you. ▶ What People Are Saying: "gem for Apple platforms – gorgeous, fluid" — Peter Kirn, createdigitalmusic.com "stunning!" — Richard Devine, devinesound.net "Remarkable gesture control" — sequencer.de ▶ Join our forum and Discord community! ▶ What You Get: • Complete modular environment — free to download and explore • Pro Module series — premium modules available as in-app purchases • Available on iPhone, iPad, and Mac with iCloud sync • Standalone app or AUv3 plugin • Deep node library for building from scratch • Extensive module library for synthesis and sound design • Multi-channel signal flow for polyphony and complex routing • Next-gen multi-core audio processing • Smooth, high-performance graphics even with massive patches • MIDI I/O with MIDI learn • GLSL shader node for creating advanced visuals • Lua scripting for custom DSP and vector graphics Terms of Use: https://audulus.com/terms.html

Screenshots

Audulus 44 screens

Verdict

The call

The clearest difference is price: Audulus 4 at Free against SynthMaster 2's $14.99. Audulus 4 also leads on ads (none vs shown) and device support (3 vs 1). SynthMaster 2's advantage is rating (4.8 vs 4.3) and ratings volume (451 vs 74). On review sentiment, update cadence, in-app purchases and monetization model there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Audulus 4 is free to download; SynthMaster 2 costs $14.99 up front. SynthMaster 2 sells 32 one-off in-app purchases and Audulus 4 sells 27 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

SynthMaster 2 holds the better App Store score, 4.8 against 4.3. That said, the two scores are not equally well evidenced: SynthMaster 2 has 451 ratings behind it against 74, so its average is the more settled of the two. Written reviews split almost evenly too, at 68% and 69% positive.

UpkeepUpdate frequency

SynthMaster 2 ships an update every 3 weeks, Audulus 4 monthly. The most recent releases landed on September 23, 2026 and September 12, 2026 respectively.

Scorecard6 real differences · 4 level
SynthMaster 2 versus Audulus 4: the parameters behind the verdict, then further details
ParameterSynthMaster 2Audulus 4
Price$14.99Free — better
Rating4.8 (451 ratings) — better4.3 (74 ratings)
Positive reviews68.5% of reviews69.2% of reviews — better
Number of ratings451 — better74
Update frequencyEvery 3 weeks — betterMonthly
AdsYesNo — better
In-app purchasesYesYes
MonetizationFree with in-app purchasesFree with in-app purchases
DevicesiPadiPhone, iPad, Mac — better
Requires iOS15 — better18.0
Further details — not scored
Size918 MB103 MB
Age rating4+4+
DeveloperKV331 AudioAudulus LLC

Customer experience

SynthMaster 2

All ratings407 ratings
Positive94.3%
Neutral2.2%
Negative3.4%
Written reviews111 reviews
Positive68.5%
Neutral16.2%
Negative15.3%

Audulus 4

All ratings74 ratings
Positive82.4%
Neutral4.1%
Negative13.5%
Written reviews78 reviews
Positive69.2%
Neutral10.3%
Negative20.5%

User reviews

SynthMaster 2

From 451 App Store ratings

What we love

  • 🚀 Best synth on iPad
  • 👍 Delicious sound
  • 👍 Tremendously powerful synth
  • 👍 Great synth with complex possibilities and great sound(s)
  • 👍 Perfeito

Room to improve

  • 🐛 Auswahl der Modulationsquellen funktioniert nicht richtig
  • 🐛 Echt schlecht
  • 🐛 Broken Preset System for a powerful synth
  • 🐛 Please fix the OSC behavior on Square and Saw
  • 🐛 Preset issues

Audulus 4

From 74 App Store ratings

What we love

  • ✨ Powerful modular environment
  • 💡 Deep DSP programming capabilities
  • 🎨 Intuitive and beautiful UI
  • 🚀 Seamless workflow across devices
  • 📚 Great for learning synthesis

Room to improve

  • 💸 Expensive in-app purchases/subscriptions
  • ⚠️ Steep learning curve for beginners
  • 📱 UI issues on mobile (scrolling, view obstruction)
  • 📉 High CPU usage
  • ❓ Lack of comprehensive documentation

Bugs and requests

SynthMaster 2

Reported bugs

4 issues
  • Presets not loading correctly
  • Modulation not working after loading project
  • Skin resets to default
  • App crashes frequently

Requested features

2 requests
  • Pitch bend/glide for imported samples
  • Integration with AUM audio mixer

Audulus 4

Reported bugs

13 issues
  • iOS 18 compatibility issues (app not working)
  • Save presets but no 'Load' button
  • Undo command issues with DAWs
  • CMD+Z causing data loss
  • Opt+drag not duplicating modules
Show 8 more
  • Plugin window not resizable
  • Menu filtering not functioning properly on iPhone
  • Select and Import buttons not working
  • Blank screen on open
  • App freezes on iPad Pro
  • Black screen on launch after update
  • No modules appearing after iOS 18 update
  • Patches not appearing after iOS 18 update

Requested features

7 requests
  • Add 'Load' button for presets
  • Improve DAW integration (Undo, duplicate)
  • Resizable plugin window
  • More modules (FFT/IFFT, granular buffering)
  • Add CC in module
Show 2 more
  • Sync to host as AUv3
  • Make upgrade path clearer from Audulus 3

In-app purchases

32 purchases

SynthMaster 2

One-time32
  • BigTone Tableworks Vol.2$1.99
  • Burak Yeter Synth Sounds Vol1$1.99
  • Aiyn Zahev Expansion 1$1.99
Show 29 more
  • BigTone Tableworks Vol.1$1.99
  • Michael Kastrup Expansion$1.99
  • EDM Stars Volume 1$1.99
  • Nori Ubukata Pop Hits Vol.4$1.99
  • Rob Lee EDM Expansion Vol.2$1.99
  • Alonso Sound Future Rave$1.99
  • Nori Ubukata Pop Hits Vol.1$1.99
  • BigTone Techno Bits Vol.1$1.99
  • Club Sequences Vol.1$2.99
  • Historical Synth Giants Vol.3$2.99
  • Dawn of Electronic Music Vol.2$2.99
  • Nori Ubukata Art Rock Basics$2.99
  • BigTone Analog Basics 02$4.99
  • BigTone Analog Basics$4.99
  • BigTone Signature Sounds Vol.1$4.99
  • NU Sounds of the World$4.99
  • Historical Synth Giants Vol.4$4.99
  • Historical Synth Giants Vol.1$4.99
  • Historical Synth Giants Vol.2$4.99
  • Japan Vintage$4.99
  • NatLife Future Bass Sounds$4.99
  • Danyella EDM Expansion Vol.1$4.99
  • Dawn of Electronic Music Vol.1$4.99
  • Dawn of Electronic Music Vol.3$4.99
  • Rob Lee EDM Expansion Vol.3$4.99
  • Natlife Disco Funk$4.99
  • Insigne Essentials 4 Clubbin$4.99
  • Desktop Presets Upgrade$9.99
  • All Expansions Bundle$49.99
27 purchases

Audulus 4

Subscriptions2
  • Audulus Pro (1 Month)7 Days trial$4.991 Month
  • Audulus Pro (1 Year)7 Days trial$29.991 Year
One-time25
  • 1-shot Sample$1.99
  • P-Train$2.99
  • CLK RS-1$3.99
Show 22 more
  • CG-1 Chord Generator$3.99
  • CLK Clock Generator$4.99
  • MetaEnvelope$4.99
  • Modal Percussion$4.99
  • CLK: TimeWarp$4.99
  • CPR-1$4.99
  • LMT-1$4.99
  • MS-FUNC$5.99
  • CLK SS-516$7.99
  • J-23 Reverb$7.99
  • J-23 Effects$7.99
  • CLK GS-1$7.99
  • Chaos LFO Bundle$7.99
  • ARP-1$7.99
  • CPR-3$7.99
  • SynD-K1$7.99
  • TRIKOR VCO$9.99
  • CLK Tools Bundle$9.99
  • Essential Synth Bundle$9.99
  • VCF Bundle 1$9.99
  • J-23 Space Console$14.99
  • Patch Editing$29.99

Questions

Is SynthMaster 2 free?
SynthMaster 2 costs $14.99, and also offers in-app purchases.
Is Audulus 4 free?
Audulus 4 is free to download, with in-app purchases available.
Which has better reviews, SynthMaster 2 or Audulus 4?
SynthMaster 2 is rated higher. SynthMaster 2 averages 4.8 out of 5 from 451 ratings, while Audulus 4 averages 4.3 from 74 ratings.
Do SynthMaster 2 or Audulus 4 have ads?
SynthMaster 2 shows ads; Audulus 4 does not.
Which is updated more often, SynthMaster 2 or Audulus 4?
SynthMaster 2 ships an update every 3 weeks, and Audulus 4 monthly. Most recently, SynthMaster 2 was updated on September 23, 2026 and Audulus 4 on September 12, 2026.

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