Geo Synthesizer vs PaSSBot
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Geo Synthesizer
This app is an expressive musical instrument and MIDI controller designed for multitouch surfaces. It offers advanced pitch control, custom sounds, and the ability to control external instruments or virtual MIDI apps. It also supports AudioBus for interconnecting audio apps.
- Expressive multitouch interface
- Advanced pitch bending
- MIDI output
- AudioBus support
- Customizable performance menus
- Multiple temperament options
- Load SampleWiz presets
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Geo Synthesizer is a musical instrument and MIDI controller. Originally a collaboration of Wizdom Music's Jordan Rudess and Kevin Chartier (MorphWiz, SampleWiz) and Rob Fielding (Mugician), Geo Synthesizer is an incredibly expressive musical instrument specifically created for a multitouch surface. Jordan is now working with Roli-Labs, creators of the amazing Seaboard instrument on an exciting future for Geo Synthesizer and it's users! A comprehensive Geo Synthesizer manual is available at: http://www.wizdommusic.com/GeoSynth/manual.html Jordan says: "Since touching a preliminary piano keyboard on an iPhone screen and realizing the amazing potential for musical expression on a multitouch device, I have been inspired to create next-generation musical instruments for iOS. Geo Synthesizer is a dream come true in many ways. It is the fastest truly playable iOS instrument that I have put my hands on to date. I can fly through the range of an instrument while expanding on the kind of advanced pitch control we introduced in MorphWiz. As someone who grew up with synthesizers, I can tell you that pitch bending has never been this good! "Geo features many of my custom sounds and in addition, Geo is also a MIDI controller, so you can use it with any external midi instrument or virtual MIDI. Virtual MIDI allows you to control an app running in the background on the same device! Geo Synthesizer also now features AudioBus, a technology that allows one to interconnect audio apps in exciting new ways! A great feature of Geo is that internally and externally we send independent voices on each note played, so as an example, you can pitch bend one note and not the other, or add unique expression on every note! I can't wait to see the YouTube videos of all of you guys rocking out with Geo Synthesizer!!!" Features: - AudioBus - ability to load waveforms from SampleWiz presets - octave rounding for effortless soloing over large ranges - whammy slider with absolute and relative modes - 12ET, 24ET, 53ET, and 665ET temperament options - mono, string, and full-polyphony modes - tuning and transposition controls - snap speed control to affect how quickly the instrument pulls notes in tune - playing surface options for number of rows and columns on screen - octave and fifth harmonics synthesis options to rich, organ-like sounds - gain control to add distortion to the sound - FM and touch FM controls for timbal variation - mono out for use with guitar amps - sine, sawtooth, square, and custom (SampleWiz) wave options - attack and release controls - synthesis body control - lowpass filter with resonance - stereo delay - reverb - MIDI output with polyphonic note bending and multiple configuration options to allow compatibility with a wide range of hardware and software synthesizers - performance menu lets you make your own custom menu so all the controls you need are always right at your fingertips - 40 presets carefully selected by Jordan Rudess, including patches from Jordan's personal sound library
PaSSBot
This app is a stochastic filter bank audio processor for iPad, offering advanced sound manipulation with various filter types and powerful stochastic generators. It allows for precise control over filter parameters and harmonic distribution, ideal for creating complex audio textures.
- Stochastic filter bank audio processor
- Multiple filter types (Biquad, Ladder, SEM, Resonators)
- Up to 64 filters in stereo
- Powerful stochastic generators
- Individual filter parameter control
- Harmonic distribution options
- Precision DSP rendering (<1ms control rate)
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PaSSBot is a unique stochastic filter bank audio processor. The desktop VST/AU version of PaSSbot has already arrived in February 2020 and this iOS version is equivalent to the latest version 2.1. PaSSBot filter types are Biquad, StateVariableFilter, Ladder, SEM and Resonators. With behaviors of bandpass, Lo + Hipass, Notch and up to 64 of them in true stereo ! The user can set values of center frequency, gain and resonance of the each filter, which will be then eloborated with powerful stochastic generators ( 4 independent GENs for each filter ) with continuous or discrete probabilistic distributions but also with standard waveforms. One can set each filter parameters individually, but also distribute them in harmonic order, again the harmonic spread ratio can be set by the user or even can be modulated by a GEN. Precision DSP rendering, less than 1milisec. control rate precision. The filters can run continuously or be triggered manually. In that case, each filter will be applied an independent AR envelope with configurable random duration. Important notes : - A recent iPAD model is being recommended and also setting the host buffer size to 128 or higher greatly helps to the CPU needs which also heavily depends on the number of parallel filters being used. - The resonators can be sensitive to input signal level. - The PaSSBot manual can be found at this link. https://www.sonic-lab.com/PaSSBot_files/PassBot_manual.pdf sonicLAB PaSSBot youtube playlist : https://www.youtube.com/playlist?list=PLP0cOkraQHDYUoMG6BETTN1eGm-Kq5z0T
Screenshots
Verdict
The clearest difference is price: Geo Synthesizer at $9.99 against PaSSBot's $34.99. Geo Synthesizer also leads on device support (3 vs 1) and iOS requirement (9.0 vs 11.0). PaSSBot's advantage is rating (5.0 vs 3.3) and review sentiment (100% vs 68%). On ratings volume, 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
Geo Synthesizer costs $9.99 and PaSSBot $34.99 up front. Neither carries in-app purchases, so what you see is what you pay.
PaSSBot holds the better App Store score, 5.0 against 3.3. Both are backed by a comparable volume of ratings — 19 and 8 respectively. Written reviews point the same way: 68% of Geo Synthesizer's written reviews are positive against 100% of PaSSBot's.
Geo Synthesizer ships an update every 11 months, PaSSBot every 4 months. The most recent releases landed on October 24, 2026 and October 23, 2026 respectively.
| Parameter | Geo Synthesizer | PaSSBot |
|---|---|---|
| Price | $9.99 — better | $34.99 |
| Rating | 3.3 (19 ratings) | 5.0 (8 ratings) — better |
| Positive reviews | 68.4% of reviews | 100.0% of reviews — better |
| Number of ratings | 19 — better | 8 |
| Update frequency | Every 11 months | Every 4 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod — better | iPad |
| Requires iOS | 9.0 — better | 11.0 |
| Further details — not scored | ||
| Size | 27 MB | 11 MB |
| Age rating | 4+ | 4+ |
| Developer | Wizdom Music LLC | SonicPlanet Audio Video Teknolojileri Anonim Sti. |
Customer experience
Geo Synthesizer
PaSSBot
Bugs and requests
Geo Synthesizer
Reported bugs
18 issues- Glitchy sound on iPad Pro
- App not working correctly
- No longer works on iPadOS
- Clicking sound on iPhone 6
- Core MIDI not working like before (iOS 9)
Show 13 moreShow fewer
- Crashing on launch (iOS 8.3)
- Audiobus initialization problem
- App crashes after last update
- New presets can't be loaded
- Envelope filters can't be adjusted
- No access to menu config page
- App shuts down on boot up (OS5)
- Crashes on start-up (iPad 2)
- Doesn't work on iPhone 4S
- Sounds sometimes drop out
- Horribly noisy until volume adjusted
- No smooth transitions between notes
- SampleWiz not working with it
Requested features
20 requests- Update for iPadOS
- Fix glitchy sound on iPad Pro
- Support for Bluetooth MIDI
- Refund option
- Fix zooming issue on iPhone 11
Show 15 moreShow fewer
- Add more columns like GeoShred
- Output MIDI note velocity based on touch pressure
- 3D Touch for velocity and aftertouch
- Assignable magic slider for FM or volume swells
- Broader sound library
- More control over MIDI output
- SF2 import for sounds
- MIDI input for live use
- Assign a major 3rd break between rows
- Record feature within the app
- Copy and paste functionality
- More intuitive menus and buttons
- More sophisticated patch programming
- Multi-channel pitchbending support
- More tutorial materials for technique and creativity
PaSSBot
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Geo Synthesizer
No in-app purchases
PaSSBot
No in-app purchases









