Comparison

iVoxel vs Kauldron Synthesizer

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

Head to head
About

iVoxel

This app transforms your voice into a singing machine using a powerful vocoder and synthesizer. It allows real-time voice manipulation, pitch correction, and the creation of unique vocal effects from recorded speech.

Highlights
  • Real-time voice analysis and resynthesis
  • 20+2 Channel vocoder
  • Pitch follower and automatic tuning
  • Voice spectrum recorder (voxels)
  • Included prerecorded voxels
  • Live keyboard playback of vocoded voice
  • Polyphonic synthesizer with analog waves
Features
Read full description

iVoxel is not only an amazingly sounding vocoder - the unique concept of iVoxel turns this vocoder into a singing machine. iVoxel is a combination of a voice optimized synthesizer and a vocoder. The vocoder part is based on the Matrix vocoder from VirSyn used by many famous artists - one of them the well known german group Kraftwerk. The channel filters used by iVoxel are based on the Sennheiser Vocoder VSM201 resulting in a rich and fat analogue sound characteristic. The pitch follower and automatic tuning let you sing correct to a selectable scale. You can use iVoxel in many different ways: As a realtime vocoder talking into the microphone while playing tunes on the keyboard. The sound character of your voice can be changed in many different aspects like pitch, gender or breath noise. Use it to sing over your favorite iTunes song ! Record the analyzed spectrum of phrases and words from your own voice. Then use this voxel to play with your own voice on the keyboard or with the build in sequencer. Nearly 300 hundred prerecorded voxels are already included. iVoxel is Audiobus compatible and can be used in the Input, Filter and Output slots in the Audiobus signal chain. The carrier signal and the vocal signal can now be fed by any Audiobus compatible Apps. The output of your creations can be recorded to an audio file which you can use with other Apps and programs for further processing. Features: • Realtime analysis/resynthesis of your voice • 20+2 Channel vocoder • Pitch Follower and automatic tuning correction to selectable scale • Realtime pitch to MIDI Note converter • Voice spectrum recorder (voxels) • Nearly 300 prerecorded voxels included • Play your vocoded voice live on keyboard. Drag for slides and vibrato.  • Polyphonic sequencer for notes & lyrics • Voice optimized polyphonic synthesizer with up to 64 analog waves • Time warping of voxels • Gender changer • Breath noise • Pitch vibrato with delay • Hi-end Reverb and Chorus/Delay effects • Export/Import of projects and voxels • Export of audio recordings • Upload recordings to SoundCloud • Copy audio recordings to Clipboard • Virtual MIDI and Background audio • flexible MIDI control for Gender and Vibrato • compatible to Korg/WIST standard • CoreMIDI • Audiobus 2 support (Input/Filter/Output) with state saving (requires iOS 7 or newer)

About

Kauldron Synthesizer

This app combines classic analog synth warmth with AI-powered sound design. It offers intelligent preset generation, extensive modulation options, and a powerful arpeggiator for creating rich synth textures.

Highlights
  • AI-powered preset generation (SPAWN²)
  • Analog modeling oscillators
  • Extensive modulation matrix
  • Dual XY-pads for control
  • Powerful arpeggiator
  • AUv3 plugin support
  • Over 900 presets
Read full description

Kauldron is where classic warmth meets Artificial Intelligence. One of our toniest and punchiest synths, Kauldron features a completely new analog modeling technology. The full spectrum of rich synth textures is bolstered by the groundbreaking SPAWN intelligent preset generation system that allows new patches to be created at the touch of a button. Abounding with pure hard-hitting tones, Kauldron requires little to no FX or production gimmicks to sound big. Kauldron is designed with modulation and fine dynamic control in mind. The two fully-featured LFOs and the mod envelope combine with a wide variety of MIDI learnable controls to manipulate multiple parameters. Everything is easily set up in a clearly laid out ‘mod matrix.’ The dual XY-pads can be used for controlling modulation or a wide range of synth parameters. MIDI aftertouch can be routed via the matrix for even greater control over expression and tonality. Kauldron also debuts the next generation of our Artificial Intelligence preset creation system, SPAWN². Completely reimagining the groundbreaking SPAWN algorithms in our hugely popular Magellan, the new SPAWN² gives you unprecedented control over generating presets. In the expert mode, you can accomplish anything from subtle ‘variations on a theme’ to bold new sounds. In the basic mode, where Kauldron does all the thinking, you get preset after usable preset with just a touch. This is not simple randomization: it is the power of A.I. put to benevolent use! Kauldron also includes its AUv3 plugin version so that you can seamlessly run multiple instances in your favorite DAW. Powerful arp with both live & program modes; comprehensive MIDI features with effortless MIDI learn; over 900 presets; recording, sharing, these are just some of the features brewing inside Yonac’s Kauldron. Selected specs include, SYNTH • 3 analog modeling oscillators w/ multiple waveforms & true PWM • FM via Osc 2 • Maximizer module with drift, spread & voice count for huge, stereophonic all-synth sounds • New vAnalog filter design w/ ‘dirt’ overload for even warmer, harmonically complex tones • Dedicated filter ADSR envelope • Filter tracking, contour & more • Pink/white noise generator • Osc. phase reset & sync • Retro & modern glide algorithms • Virtual VCA envelope with 2 attack types • Poly/mono operation • Legato mode for buttery smooth passages • Extensive modulation options via the ‘mod matrix’ • 2 LFOs w/ BPM sync, keytracking, trigger mode & more • Assignable mod envelope • 23 mod targets • 11 mod controllers, including aftertouch, velocity & keytracking • 2 XY-Pads for controlling mod targets or synth parameters • Arpeggiator with live & program modes, 11 algorithms, gate, swing, note value, octaving & more • Stereo mod effect with chorus & flanger modes • BPM-syncable stereo delay • Studio quality reverb w/ 7 room types, damping, time & mix • 900+ presets in a wide variety of styles & sounds SPAWN² • Automatic preset generation via artificial intelligence • Generate infinite new, usable presets at the touch of a button • Expert mode lets specify Variation & Autonomy for each major synth module • 3 unique A.I. algorithms • Auto arp programming in any listed scale PRO FEATURES • AUv3 - use as Audio Unit instrument plugin on iPad & iPhone • Fullscreen AU mode • Extensive MIDI: MIDI learn, aftertouch, MIDI CC map save/share, KB mapping, program changes & more APP • iPhone & iPad Compatibility • Powerful YPAT2 preset management system • Classic or ribbon key controller • Ribbon controller: Poly aftertouch into Kauldron • Ribbon controller: Settable musical key & scale • Classic KB: Velocity w/ sensitivity setting • Tapedeck: Record, loop & share • Metronome • Tap BPM

Screenshots

iVoxel1 screens
Kauldron Synthesizer4 screens

Verdict

The call

The clearest difference is rating: Kauldron Synthesizer at 4.6 against iVoxel's 3.3. Kauldron Synthesizer also leads on review sentiment (80% vs 55%) and ratings volume (136 vs 17). iVoxel's advantage is update cadence (every 5 months vs every 49 months) and price ($6.99 vs $9.99). On ads, in-app purchases, monetization model and device support 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

iVoxel costs $6.99 and Kauldron Synthesizer $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Kauldron Synthesizer holds the better App Store score, 4.6 against 3.3. That said, the two scores are not equally well evidenced: Kauldron Synthesizer has 136 ratings behind it against 17, so its average is the more settled of the two. Written reviews point the same way: 55% of iVoxel's written reviews are positive against 80% of Kauldron Synthesizer's.

UpkeepUpdate frequency

iVoxel ships an update every 5 months, Kauldron Synthesizer every 49 months. The most recent releases landed on November 6, 2026 and November 3, 2026 respectively.

Scorecard6 real differences · 4 level
iVoxel versus Kauldron Synthesizer: the parameters behind the verdict, then further details
ParameteriVoxelKauldron Synthesizer
Price$6.99 — better$9.99
Rating3.3 (17 ratings)4.6 (136 ratings) — better
Positive reviews54.9% of reviews79.7% of reviews — better
Number of ratings17136 — better
Update frequencyEvery 5 months — betterEvery 49 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better15.6
Further details — not scored
Size46 MB32 MB
Age rating4+4+
DeveloperHarry GohsYonac Inc.

Customer experience

iVoxel

All ratings17 ratings
Positive52.9%
Neutral5.9%
Negative41.2%
Written reviews204 reviews
Positive54.9%
Neutral14.7%
Negative30.4%

Kauldron Synthesizer

All ratings136 ratings
Positive88.2%
Neutral6.6%
Negative5.1%
Written reviews74 reviews
Positive79.7%
Neutral9.5%
Negative10.8%

User reviews

iVoxel

From 17 App Store ratings

What we love

  • 🎵 Excellent sound quality and vocoder capabilities
  • 💡 Innovative vocal sound design tool with unique spectral shaping
  • 🎹 Versatile instrument for creating robot/Kraftwerk-style vocals
  • 👍 Intuitive once users understand the interface
  • 🎧 Works well with built-in microphone for live vocoding

Room to improve

  • 🐛 Frequent crashes and stability issues across iOS versions
  • ❌ Poor documentation and unclear user interface
  • 🔇 Volume levels inconsistent - too quiet or too loud
  • ⚠️ Unreliable audio input/output routing
  • 🚫 Limited microphone compatibility and connection issues

Kauldron Synthesizer

From 136 App Store ratings

What we love

  • ✨ Warm and rich sound
  • 👍 Easy to use interface
  • 💡 Great presets included
  • 🚀 Powerful sound engine
  • 🌟 High quality emulation

Room to improve

  • 🐛 Buggy AUv3 implementation
  • 🔊 Shrill noise issue
  • 🔇 No Bluetooth speaker support
  • ⚠️ Strange behavior/no reset
  • 📉 Lacks oomph/personality

Bugs and requests

iVoxel

Reported bugs

14 issues
  • App crashes on launch or during use
  • Hangs when changing presets or settings
  • Random background noise and clicking sounds
  • Microphone input not recognized or working intermittently
  • No sound output in standalone or Audiobus mode
Show 9 more
  • Touch controls unresponsive in certain screen areas
  • Import/export functionality broken
  • Sequencer not playing sounds or producing audio
  • Recording functionality causes crashes
  • Compatibility issues with iOS 18, iOS 17, and older versions
  • Audiobus carrier wave option not appearing
  • MIDI stuck notes and keyboard responsiveness issues
  • Display rendering issues on certain devices
  • Audio routing not working with external interfaces

Requested features

14 requests
  • AU v3 plugin support for modern DAW integration
  • Audiobus 3 and IAA (Inter-App Audio) support
  • Core MIDI support beyond Akai controllers
  • Lightning to USB audio interface compatibility
  • Custom word/text input for voice synthesis
Show 9 more
  • Metronome for sequencer alignment
  • Direct audio export and playback within app
  • Improved sequencer with copy/paste/undo functionality
  • Bluetooth audio output support
  • Sync options for modern music production
  • Better microphone input handling
  • Volume normalization and better level controls
  • Ability to delete recorded voxels
  • More comprehensive tutorial and help system

Kauldron Synthesizer

Reported bugs

15 issues
  • Oscillators cannot be set to -1 octave
  • Shrill noise
  • No Bluetooth speaker output
  • Fails to reload with Logic projects
  • Cannot load into Logic Pro
Show 10 more
  • Starts and quits on latest iOS
  • AUv3 bug: receives notes regardless of track selection
  • AUv3 implementation flaky, random crashes
  • AUv3: plays all instances simultaneously
  • Bug with Garageband: duplicates patterns
  • MIDI learn functions not saved
  • Sometimes glitchy
  • XY pad movements not recorded as automation
  • CPU killer on iPad 4
  • No function to share sounds

Requested features

11 requests
  • Bring synths/effects to macOS
  • Mac App version
  • More comprehensive FX section (distortion/saturation)
  • MIDI-out for arpeggiator
  • Drum machine, PAD launcher, DAW
Show 6 more
  • Browser download feature
  • Sequencer in Kauldron
  • Effects tool
  • Version history
  • More developer responses/support
  • Dark mode option

In-app purchases

None

iVoxel

No in-app purchases

None

Kauldron Synthesizer

No in-app purchases

Questions

Is iVoxel free?
iVoxel costs $6.99, with no in-app purchases.
Is Kauldron Synthesizer free?
Kauldron Synthesizer costs $9.99, with no in-app purchases.
Which has better reviews, iVoxel or Kauldron Synthesizer?
Kauldron Synthesizer is rated higher. iVoxel averages 3.3 out of 5 from 17 ratings, while Kauldron Synthesizer averages 4.6 from 136 ratings.
Do iVoxel or Kauldron Synthesizer have ads?
Neither iVoxel nor Kauldron Synthesizer shows ads.
Which is updated more often, iVoxel or Kauldron Synthesizer?
iVoxel ships an update every 5 months, and Kauldron Synthesizer every 49 months. Most recently, iVoxel was updated on November 6, 2026 and Kauldron Synthesizer on November 3, 2026.

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