Pendulums vs ThunderBeast
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Pendulums
This app generates unique musical compositions based on the principles of chaos theory and physics. Users can interact with a pendulum system to influence the music's structure and mood, with no pre-recorded loops or arrangements. It offers a wide range of scales, instruments, and accompaniment styles for creative exploration.
- Chaos theory-driven music generation
- Interactive pendulum control
- Dynamic song structure based on physics
- 26 diverse musical scales
- 8 accompaniment styles
- Multiple sampled and synthesized instruments
- Exportable MIDI files
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Twin Double Pendulums is more chaotic than my other engine using 2 Lorenz. This is more suited for Oriental music like Koto. The pendulums are released from the same angle, one of them offset by a ten-thousandth of a degree. Both drive a lead voice. While the runs agree the two voices land on the same note, so you hear a single line over a rolled arpeggio. As the gap opens the twin becomes a real second voice, chords swell in behind it, and once the runs have parted for good the whole band is in. Nothing is pre-recorded and nothing loops. Every release is new. THE SONG FORM IS THE PHYSICS There is no bar counter and no scripted arrangement — the piece is however long the pendulums stay together. Their separation is the structure: IN SYNC — lead and twin on the same note, one line over an arpeggio that re-voices itself every bar. DRIFTING — the twin splits into real intervals; chords enter and swell. DIVERGED — bass enters, the grooves open up, the mood engine wakes. Watch it happen: the gap is plotted live on a log scale with the running Lyapunov exponent beside it, so you can see the divergence coming before you hear it. DRAG THE RIG Pull the pendulum round to set the release angle and both twins let go again, from anywhere in the piece. Release it inside about 79 degrees and the motion stays regular, the twins never part, and the solo holds indefinitely — chaos is a regime, not a law, and the scope draws you that boundary while you drag. Outside it, the twin offset sets how long the solo lasts before chaos takes over, though only logarithmically: each extra decimal place buys about the same few seconds again. CHAOS PROPOSES, A POLICY DISPOSES The far bob's position proposes a region of pitches rather than one note. A Markov policy then decides what actually plays, learning from its own output and rewarding intervals that sound consonant. Slide BLEND to choose who wins. WHAT YOU GET • 26 scales — major and minor modes, pentatonics, blues, whole tone, harmonic and melodic minor, altered, both octatonics, and folk scales from Japan, China, Egypt, Spain, Arabia and Hungary • 8 accompaniment styles — chaos grooves, jazz comping with walking bass, stride piano, Alberti bass, classical, arpeggios, oriental rolls, ambient • Four sampled instruments — grand piano, koto, zither and shakuhachi — plus synthesised voices: soft piano, glass, strings, FM bell, AM organ, pluck, fat saw and more • 6 moods on a valence/arousal plane, from serene to tense, driving chord quality, register, tempo and note length • Expression built into the physics: ring, note bend, grace notes, and octave doubling called by the second bob • Live displays — the rig itself, the divergence chart, the note-probability distribution the engine samples from, and the mood point • Record a take and export it as a standard MIDI file to the Files app — lead, twin, chords and bass on separate tracks TWO AUDIO UNITS Pendulums ships as an instrument AUv3 and as a MIDI processor AUv3, so it can either play its own sounds or sequence any other instrument in your host. Lead, twin, chords and bass each send on their own MIDI channel, so one instance can drive four different instruments. Both Audio Units follow your host's transport and tempo — hit play in AUM, GarageBand, Logic, Cubasis or Zenbeats and it locks to the grid, on the bar line, even if you start mid-bar. One install registers both. CREDITS Sampled piano: Salamander Grand Piano by Alexander Holm (CC BY 3.0). Koto and shakuhachi: FluidR3 GM soundfont by Frank Wen (MIT). Zither: đàn tranh from the Versilian Community Sample Library (CC0).
ThunderBeast
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Rain, wind and thunder, all synthesized in real time. No samples, no loops. Every storm ThunderBeast makes is a storm happening for the first time. EIGHT CITIES, EIGHT SKIES A New York night storm. London drizzle. A Miami squall. Seattle mist. The Bangkok monsoon. A Reykjavik gale. An evening shower in Kyoto. A Cape Town storm front. Choose a preset and the scenery, the weather and the colour of the panel change together, so the city you are listening to is the city in front of you. TEN WEATHER CONTROLS Precipitation and drop size shape the rain; wind speed, gust and turbulence move the air. Storm rate decides how often lightning happens and storm energy decides how heavy each strike lands, while cell distance walks the storm from directly overhead out to the horizon. Humidity and pressure change the whole feel of the sky, and width and gain finish it. FOUR KINDS OF LIGHTNING A crack at close range, thunder that rolls, strikes that repeat, a sheet of light across the whole sky - each one carrying the swell that comes back off the landscape. The bolt is drawn on screen as it happens and changes colour as the storm moves away. No two strikes are ever the same. PLAYABLE WEATHER Play from C2 up and the rain rings at that pitch. Chords and melodies come out of the falling rain. Play below C2 and lightning strikes instead: pitch sets the distance, velocity sets the weight. Twelve hardware controller presets are built in; the mod wheel is storm energy and the sustain pedal is lightning. STANDALONE AND AUv3 Use it on its own, or as an AUv3 plug-in in GarageBand, Logic Pro and others. START FREE Three cities are free from the first launch. ThunderBeast Pro is a one-time purchase, not a subscription: it opens the remaining cities (eight in all) and adds recording and export to WAV, AIFF and FLAC.
Screenshots
Verdict
The clearest difference is update cadence: Pendulums at every 4 days against ThunderBeast's every 2 weeks. On price, ads, in-app purchases 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
Both are free to download. Pendulums sells 1 one-off in-app purchase and ThunderBeast sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
Pendulums ships an update every 4 days, ThunderBeast every 2 weeks. The most recent releases landed on November 6, 2026 and October 31, 2026 respectively.
| Parameter | Pendulums | ThunderBeast |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (3 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 4 days — better | Every 2 weeks |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod, Mac — better | iPhone, iPad, Mac |
| Requires iOS | 15.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 25 MB | 63 MB |
| Age rating | 4+ | 4+ |
| Developer | Wilfredo Jr Bigol | Tomocreate, Inc. |
In-app purchases
Pendulums
- Unlock AUv3$2.99
ThunderBeast
- ThunderBeast Pro$9.99









