Kauldron Synthesizer vs VAPoly
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
- AI-powered preset generation (SPAWN²)
- Analog modeling oscillators
- Extensive modulation matrix
- Dual XY-pads for control
- Powerful arpeggiator
- AUv3 plugin support
- Over 900 presets
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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
VAPoly
This virtual analog synthesizer offers 8-voice polyphony with built-in effects, a sequencer, and parameter automation. It functions as a standalone app or an Audio Unit Extension, supporting iCloud Drive and various MIDI and audio export options.
- Virtual analog 8-voice polyphony
- Built-in effects (delay, chorus, reverb, etc.)
- 16-bar sequencer with parameter automation
- Oscillators with modulation capabilities
- Standalone app and AUv3 extension
- iCloud Drive support for cross-device projects
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VAPoly is a virtual analog 8 voice polyphonic synthesizer for iPhone, iPad and Mac. VAPoly features built-in effects, built-in sequencer, parameter automation, oscilloscopes and spectrum analyzer. VAPoly works as a stand alone or as an Audio Unit Extension (AUv3). Stand Alone supports Ableton Link, Bluetooth MIDI, MIDI IN/OUT and audio file export. The synth features two oscillators, two ADSR envelopes, a high pass filter, a low pass filter and an amplifier per voice. The oscillators are capable of wide variety of modulation to shape the sound. The low pass filter is modeled on cascaded OTA filter circuit for classic analog sound. The Effects include delay, chorus, flanger, reverb, eq, and compressor. The sequencer offers ability to program 16 bar pattern per clip for total 16 clips and parameter automation. Project files can be saved in iCloud Drive to work on iPhone, iPad and Mac. Main Features Virtual analog 8 voice polyphonic synthesizer Sequencer 16 bar patterns per clip. Total 16 clips. Parameter automation. Audio Export Linear PCM format (AIFF, WAV and CAF) and compressed format (AAC) Support iCloud Drive. Support Ableton Link, Bluetooth MIDI, MIDI In / Out. Support Audio Unit Extension (AUv3) Support Universal Purchase. VAPoly works on iPhone, iPad and Mac. System Requirements - For iOS Devices, A10 Fusion or above is recommended. - AudioUnit Extension (AUv3) requires host application which support AudioUnit Extension. - AudioUnit Extension (AUv3) is supported by Apple Garage Band on iOS and macOS, and Apple Logic on Mac. For any other DAW, it depends on the application and some of them don’t support AudioUnit Extension (AUv3).
Screenshots
Verdict
The clearest difference is update cadence: VAPoly at every 3 months against Kauldron Synthesizer's every 49 months. VAPoly also leads on price ($3.99 vs $9.99) and rating (5.0 vs 4.6). Kauldron Synthesizer's advantage is ratings volume (136 vs 16). On review sentiment, ads, 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
Kauldron Synthesizer costs $9.99 and VAPoly $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
VAPoly holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: Kauldron Synthesizer has 136 ratings behind it against 16, so its average is the more settled of the two. Written reviews point the same way: 80% of Kauldron Synthesizer's written reviews are positive against 83% of VAPoly's.
Kauldron Synthesizer ships an update every 49 months, VAPoly every 3 months. The most recent releases landed on October 20, 2026 and October 26, 2026 respectively.
| Parameter | Kauldron Synthesizer | VAPoly |
|---|---|---|
| Price | $9.99 | $3.99 — better |
| Rating | 4.6 (136 ratings) | 5.0 (16 ratings) — better |
| Positive reviews | 79.7% of reviews | 83.3% of reviews — better |
| Number of ratings | 136 — better | 16 |
| Update frequency | Every 49 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 15.6 | 15.2 — better |
| Further details — not scored | ||
| Size | 32 MB | 19 MB |
| Age rating | 4+ | 4+ |
| Developer | Yonac Inc. | Ryo Togawa |
Customer experience
Kauldron Synthesizer
VAPoly
Bugs and requests
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
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- 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
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- Browser download feature
- Sequencer in Kauldron
- Effects tool
- Version history
- More developer responses/support
- Dark mode option
VAPoly
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Kauldron Synthesizer
No in-app purchases
VAPoly
No in-app purchases








