TETSUO vs FAC Gravity
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
TETSUO
This app offers a unique, generative percussion experience with no pre-loaded samples. It features a complex sound engine and a dynamic sequencer that can be unpredictable, allowing for negotiation rather than direct programming. Create and save evolving soundscapes with its section-based recording system.
- Chaotic percussion engine
- No samples or library
- Resonant filter and bitcrusher
- Dynamic 16-slot sequencer
- Randomized hit skipping
- Section-based sound recording
- AUv3 and standalone support
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TETSUO is a chaotic percussion machine. No samples, no library. One voice built out of a pitched body with noise dragged through it, a resonant filter that saturates the harder you lean on it, a bitcrusher, and a waveshaper that runs from a bit of weight to total structural failure. The sequencer is sixteen unseen slots and STEPS knob decides how many of them fire, adding and taking away hits one at a time in a fixed order, so you can strip a pattern to the bone and build it back and the same beats come home. The SKIP control works against you on purpose, stealing hits at random while it plays, so it never quite settles. MUTATE modulates the pitch at random, setting fire to voices on every turn. You do not program TETSUO so much as negotiate with it. The strip along the top is how you attempt to hold onto anything. Sixty four steps, four turns of pattern, carved into as many as eight sections. Select a section. Find a sound. Hit RECORD, and that section keeps every knob position. Change it, record the next, then hit PLAY and it walks left to right dropping each snapshot in as it reaches it, looping. Drag the dividers to give a section longer or cut it short. It keeps settings, not audio, so the engine is playing live the entire way through. Sections save with your presets and your session. AUv3 and standalone.
FAC Gravity
Create unique audio effects like Barberpole glissandos, spectral illusions, and evolving echoes. This frequency shifter offers stereo or mono processing with customizable feedback loops and modulation for dynamic sound design.
- Barberpole glissandos and spectral illusions
- Stereo or mono frequency shifting
- Spiral feedback loop with delay and filtering
- Modulation matrix with LFO and envelope follower
- Tempo-synced or MIDI-driven effects
- Dry/wet mix and optional limiting
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FAC Gravity AUv3 Plugin is a frequency shifter for creating Barberpole and Shepard style glissandos, spectral illusions, stereo rotation, chorusing, phasing, evolving echoes, infinite cosmic spaces, and all the combinations you’ll make. The plugin gives you two ways to process the audio source. In Stereo mode, each channel is shifted independently, with a Ratio control determining how closely their frequency shifts align. In Mono mode, FAC Gravity extends the internal quadrature processing to create a wide stereo image from the mono source. The frequency shift can move up or down, from subtle to more extreme spectral transformations. You can set the amount in Hz for classic Bode-style frequency shifting, make it follow your host tempo for rhythmic patterns, or even control it from MIDI notes for a more hands-on approach. A new dimension appears when you let the shifter feed back into itself with Spiral, a customizable loop with delay, blur, filtering, and different characters that shape how the sound circles, smears, interacts, and evolves over time. The result can range from bubbling textures to infinite sustained tones and noisy analog self-oscillation. Each character takes the feedback somewhere different. To dive deeper into new sonic dimensions, FAC Gravity comes with its own modulation module. The LFO, envelope follower, and flexible modulation matrix let you animate most parameters, from subtle evolving movements to complex, rhythmically reactive changes. You can even make the stereo field animate and rotate continuously by making the Width, Phase, and Pan parameters spin! You can shape the effect further by blending the processed signal with the original, while the optional limiter keeps the most extreme combinations in check. • Barberpole glissandos, spectral illusions, rotating stereo, evolving echoes • Dual Frequency Shifting, or Mono Shifting with Quadrature Stereo Widening • Organic Spiral Loop, from gentle feedback to pure analog self-oscillation • Integrated delay, diffusion blur, and independent low/high filtering • Modulation matrix, multi-source envelope follower • LFO with classic waveforms and random spline • Spinning modulation to rotate and animate the stereo field • Tempo-synced or MIDI-driven Frequency Shift, LFO, and Delay • Dry/Wet mix, optional limiting, and goniometer visualization • Advanced Responsive Design, portrait and landscape views • Universal Purchase: AUv3 for iOS (iPad/iPhone), macOS and Vision Pro The documentation is available at fredantoncorvest.com/FAC_Gravity.html This is an AUv3 Effect and requires a compatible host to work The in-app purchases are for tipping only, the app is fully functional without them
Screenshots
Verdict
The clearest difference is in-app purchases: TETSUO at none against FAC Gravity's 3. TETSUO also leads on iOS requirement (15.6 vs 17.0). FAC Gravity's advantage is ratings volume (7 vs 2). On price, rating, ads 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
TETSUO costs $9.99 and FAC Gravity $9.99 up front. FAC Gravity sells 3 one-off in-app purchases. TETSUO asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for TETSUO against 4.9 for FAC Gravity. Both are backed by a comparable volume of ratings — 2 and 7 respectively.
| Parameter | TETSUO | FAC Gravity |
|---|---|---|
| Price | $9.99 | $9.99 |
| Rating | 5.0 (2 ratings) — better | 4.9 (7 ratings) |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 2 | 7 — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Requires iOS | 15.6 — better | 17.0 |
| Further details — not scored | ||
| Size | 29 MB | 4 MB |
| Age rating | 4+ | 4+ |
| Developer | Anthony Moran | Frederic Corvest |
In-app purchases
TETSUO
No in-app purchases
FAC Gravity
- Small Tip$1.99
- Medium Tip$4.99
- Large Tip$14.99









