Comparison

Zeeon synth vs KORG iMono/Poly

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

Head to head
About

Zeeon synth

This app is a virtual analog synthesizer that recreates the sound and feel of classic hardware. It features a detailed circuit-modeling engine, powerful modulation, and multiple filter models for rich, organic soundscapes. Explore a vast array of presets and expand your sonic palette with additional sound banks.

Highlights
  • Circuit-modeling engine
  • Powerful modulation matrix
  • Dual oscillators with variable waveforms
  • Multiple filter models
  • Built-in effects unit
  • Audio Unit v3 support
  • Polyphonic step sequencer
Features
Read full description

Zeeon is a virtual-analog synthesizer built on a deeply detailed circuit-modeling engine. We’ve studied classic and modern analog synths to uncover what gives them their unmistakable character and recreated that essence with precision. The result is a unique instrument that delivers the warmth, movement, and organic depth of true hardware. While many emulations sound flat, Zeeon breathes. Every note is alive, with tight lows and shimmering highs. All audio and modulation are processed at 176 kHz (4× oversampling) for uncompromised quality across the entire spectrum. “Desktop-class sound engine … fidelity of this analog emulation goes beyond everything else on iOS.” – App Store review Features • Audio Unit v3 and standalone application with a simple polyphonic step sequencer • Powerful modulation matrix offering self-modulation and cross-layer modulation, 8 modulation slots, 17 signal sources and 41 targets available, both from modulation modules and audio signal path. This takes Zeeon into semi-modular territory. Imagine oscillator waveform, panning, filter cutoff, resonance or LP-HP mode modulated by oscillators or another layer! • 2 oscillators with continuously variable waveforms, hard-sync and sub-oscillator. Carefully simulated analog drift and PSU influence. • Filter: 3 models available: Transistor ladder low pass, OTA cascade low pass and State Variable Filter with continuously variable LP-HP + BP mode. • 2 low frequency oscillators and envelope generators per voice. • Overdrive: diode clipper, transistor saturation, wave folder, pre and post filter. • Up to 2 layers per voice. Layers can modulate each other. • Effects unit: Circuit modelled BBD chorus, bass booster, zero-delay Phaser, Stereo delay and Reverb. • 280 presets and Tutorials bank. 3 additional banks available as IAPs. Full manual and audio demos available at the BeepStreet website.

About

KORG iMono/Poly

Experience a classic analog synthesizer reborn on iOS. This app faithfully reproduces the iconic 4VCO sound engine, offering deep sound design capabilities with virtual patches and multi-effects. Seamlessly integrate it into your music production workflow.

Highlights
  • Faithful reproduction of classic 4VCO analog synthesizer
  • Deep sound design with extensive modulation
  • Eight virtual patches for expanded sound potential
  • Two multi-effect units
  • Quick access to all synth parameters
  • Integration with KORG Gadget
Features
Read full description

Reviving a classic KORG analog synthesizer. The iconic 4VCO synthesizer, reborn on iOS. The Mono/Poly analog synthesizer appeared in 1981 at the same time as the acclaimed Polysix. Not only was it a fat-sounding four-VCO monophonic synthesizer, it featured a revolutionary design that allowed it to also be used as a four-voice polyphonic synthesizer, which helped cement its legendary status. The long-awaited “KORG iMono/Poly” iPad/iPhone app completely reproduces all features of the original Mono/Poly. Four VCOs and a rich array of modulation allow a wide range of detailed sound design. New functionality such as two multi-effects units and eight virtual patches are also provided. In addition, the seamless integration that you expect from KORG’s iOS apps will fit perfectly into your music making process. The Mono/Poly has been reborn for today’s world, bringing you a unique and legendary sound. * Due to differences in CPU speed of iPads / iPhones, iPad 3rd gen/2/iPad mini/iPhone 4s are not supported, only iPad Air/iPhone 5s or later is recommended. [ Features ] • Deep 4VCO sound. A complete reproduction of the classic Mono/Poly The Mono/Poly synthesizer featured four VCOs, a dedicated envelope generator for the VCF, and also sync and cross-modulation, earning it a reputation for its detailed sound-shaping potential and its distinctive character. • Powerful virtual patches, and the latest presets to catch the scene Eight virtual patches provide the ultimate expansion of the Mono/Poly’s distinctive sound-design potential. Two multi-effect units are also provided, allowing you to create complex and broad-ranging sounds with complete freedom. • Quick access to all panels Although iMono/Poly provides a vast number of parameters, it’s designed with a screen structure that provides quick and seamless access to all of them. With a single tap, you can rotate between the main synth & key assign screen and the virtual patch & effect screen. There’s no need to open individual screens for specific functions, or to move back and forth between them. • Produce music in conjunction with KORG Gadget iMono/Poly can be used in conjunction with “KORG Gadget,” the music production DAW app that has won numerous prizes within Japan and around the world. When you install both apps, iMono/Poly appears as the “Montpellier” gadget within KORG Gadget. More info at korg.com

Screenshots

Zeeon synth3 screens
KORG iMono/Poly4 screens

Verdict

The call

The clearest difference is price: Zeeon synth at $14.99 against KORG iMono/Poly's $29.99. Zeeon synth also leads on rating (4.8 vs 4.3) and review sentiment (76% vs 62%). KORG iMono/Poly's advantage is iOS requirement (9.3 vs 15.6). On ratings volume, update cadence, ads and in-app purchases 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

Zeeon synth costs $14.99 and KORG iMono/Poly $29.99 up front. Zeeon synth sells 3 one-off in-app purchases and KORG iMono/Poly sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

Zeeon synth holds the better App Store score, 4.8 against 4.3. Both are backed by a comparable volume of ratings — 209 and 85 respectively. Written reviews point the same way: 76% of Zeeon synth's written reviews are positive against 62% of KORG iMono/Poly's.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 6, 2026 and November 4, 2026 respectively.

Scorecard4 real differences · 6 level
Zeeon synth versus KORG iMono/Poly: the parameters behind the verdict, then further details
ParameterZeeon synthKORG iMono/Poly
Price$14.99 — better$29.99
Rating4.8 (209 ratings) — better4.3 (85 ratings)
Positive reviews76.0% of reviews — better62.4% of reviews
Number of ratings209 — better85
Update frequencyEvery 2 monthsEvery 2 months
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchasesFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.69.3 — better
Further details — not scored
Size27 MB203 MB
Age rating4+4+
DeveloperBeepStreetKORG INC.

Customer experience

Zeeon synth

All ratings209 ratings
Positive93.8%
Neutral2.4%
Negative3.8%
Written reviews167 reviews
Positive76.0%
Neutral7.2%
Negative16.8%

KORG iMono/Poly

All ratings84 ratings
Positive81.0%
Neutral6.0%
Negative13.1%
Written reviews141 reviews
Positive62.4%
Neutral16.3%
Negative21.3%

User reviews

Zeeon synth

From 209 App Store ratings

What we love

  • 🎨 Excellent sound quality
  • 🎹 Intuitive and well-designed interface
  • 🔧 Flexible and deep sound design capabilities
  • 💻 Seamless integration as an AUv3 plugin
  • 🎚️ Smooth and responsive controls

Room to improve

  • 🐛 Stability issues, crashes on some devices
  • 🔌 Compatibility problems with newer iOS versions
  • 📂 Preset management could be improved
  • 🔀 Lack of MIDI learn and sequencer features
  • 🖥️ UI scaling issues on larger iPad displays

KORG iMono/Poly

From 85 App Store ratings

What we love

  • 🎶 Great sounding synth
  • ✨ Fantastic sound quality
  • 🎵 Amazing features and sounds
  • 💻 Excellent for Gadget integration
  • 💡 Versatile for sound design

Room to improve

  • 🔌 No AUv3 support
  • 🚫 Useless without AUv3
  • 💸 Waste of money without AUv3
  • 📉 Low output volume
  • 🤏 Small controls, difficult manipulation

Bugs and requests

Zeeon synth

Reported bugs

4 issues
  • Preset settings not retained after app restart
  • Synth reverts to default settings when reopening Logic Pro project
  • Crashes and freezes on certain iOS 14+ devices
  • Inability to access in-app purchases from within the app

Requested features

5 requests
  • Add MIDI learn functionality
  • Implement a more robust preset management system
  • Include a built-in sequencer with save/load capabilities
  • Improve UI scaling and layout for larger iPad screens
  • Provide better integration with inter-app audio and Audiobus

KORG iMono/Poly

Reported bugs

15 issues
  • Cannot restore expansion pack
  • Cannot find store tab
  • Scale selection broken
  • User scale does nothing
  • MIDI unstable
Show 10 more
  • Audio pops
  • Monopoly skin removed
  • Does not work with nanokey studio Bluetooth
  • IAA Panel not displaying host link, transport, record buttons
  • MIDI IAA selection not appearing in Cubasis
  • On-screen keyboard plays fixed velocity notes
  • Arpeggiator doesn't work as expected in Gadget
  • User programmed sounds not visible in Gadget
  • Patches sound different in Gadget
  • App does not take advantage of larger iPhone XS Max screen size

Requested features

42 requests
  • AUv3 support
  • Adaptive Cubasis 3 AUv3
  • More iMPC integration
  • Transfer patches to desktop VST
  • Store preset files on device/flash drive
Show 37 more
  • Keyboard portamento to filter cutoff
  • Double tap knob to zero/fine adjust
  • Save mod wheel position in preset
  • Scroll and lock keyboard to key
  • Octave switches on left with large keyboard
  • Key transpose for arpeggiator
  • Undo/redo feature
  • Portamento on/off button
  • Arpeggio rate as mod destination
  • Full-sized keyboard button
  • Turn into AUv3
  • Bring back Monopoly skin
  • Add high-pass filter (HPF)
  • MIDI sync in
  • Export/share sounds
  • Assign right Kaoss pad like left
  • AUv3 version
  • Latch button for ARP patches
  • Random feature
  • Double tap to return dials to 0
  • Right XY pad assignable
  • More extensive external MIDI controller support
  • MPE support
  • More expansion packs
  • Access user patches within Gadget's Montpellier
  • Mod destination for VCO Mod Type
  • MIDI learn for all controls
  • Link on standalone
  • Improve effects quality
  • Add Korg Prophecy
  • Add Trinity, Triton
  • Improve IAA panel functionality
  • MIDI IAA selection from host
  • Fixed velocity on-screen keyboard improvement
  • Tempo synchronization with other apps (IAA, MIDI clock, Ableton Link)
  • Improve UI for larger screens
  • Immaculate skin option

In-app purchases

3 purchases

Zeeon synth

One-time3
  • OI - Exploration Vol. 1$3.99
  • BB Z-Space$4.99
  • BB Synthwave$4.99
1 purchases

KORG iMono/Poly

One-time1
  • Expansion Factory Pack$4.99

Questions

Is Zeeon synth free?
Zeeon synth costs $14.99, and also offers in-app purchases.
Is KORG iMono/Poly free?
KORG iMono/Poly costs $29.99, and also offers in-app purchases.
Which has better reviews, Zeeon synth or KORG iMono/Poly?
Zeeon synth is rated higher. Zeeon synth averages 4.8 out of 5 from 209 ratings, while KORG iMono/Poly averages 4.3 from 85 ratings.
Do Zeeon synth or KORG iMono/Poly have ads?
Neither Zeeon synth nor KORG iMono/Poly shows ads.
Which is updated more often, Zeeon synth or KORG iMono/Poly?
Zeeon synth ships an update every 2 months, and KORG iMono/Poly every 2 months. Most recently, Zeeon synth was updated on November 6, 2026 and KORG iMono/Poly on November 4, 2026.

Other comparisons