REPUN vs 1981 FM
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
REPUN
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REPUN is an analog-minded chorus and vibrato processor for iPhone and iPad. Use it as a standalone audio app or insert the included AUv3 effect in a compatible host such as GarageBand. Its sound is built around BBD-style delay behavior, band limiting, compander contour, and controlled waveform instability. The result moves with tonal weight instead of sounding like a clean digital modulation layer placed on top of the source. FEATURES - BBD-style chorus and vibrato character - Free-running or host-tempo-synced modulation - Continuous dry-to-chorus-to-vibrato Mix control - Adjustable Rate and Depth - LFO Wave shaping - BREEZE drift and random-motion control - Instrument and line input modes - 2x and 4x processing modes - Standalone iOS/iPadOS app - AUv3 audio effect for compatible hosts TRY BEFORE UNLOCKING The working release model assumes 10 minutes of full-featured active use, shared between the standalone app and AUv3 extension. A one-time, non-consumable In-App Purchase unlocks unlimited use in both formats, with Restore Purchases available in the standalone app. Confirm this behavior in the production build before submission. REPUN works on guitars, keyboards, synthesizers, pads, drones, and melodic layers that need width, instability, or animated pitch movement.
1981 FM
This app generates complete, unique musical tracks using chaotic mathematical principles. It offers various styles, modes, and keys, with customizable FM synth sounds and effects. Tracks can be recreated using seeds and exported via MIDI.
- Chaos-driven track generation
- Four-operator FM synth engine
- Multiple musical styles and modes
- MIDI export and input
- Customizable effects (chorus, delay, reverb)
- Offline functionality
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1981 FM writes complete tracks. Press generate and you get 64 bars with an intro, verses, choruses, a break and an outro, played by a four-operator FM synth. Lead, bass, arp, pad and a drum machine, through chorus, delay and reverb. Nothing is sampled. Every note is made on the fly and no two tracks come out the same. The music comes from chaos maths. A Lorenz attractor shapes the melody, rhythm and mood. A Hénon map keeps the arpeggio moving. A logistic map handles the drum fills: turn it down and they repeat every bar, turn it up and they never do. Chaos on its own is noise, so a small model filters it. It gets rewarded for consonant intervals and practises over the chord changes before it writes anything. The CHAOS / POLICY slider decides how much say each one gets. Ten styles, and they are properly different. Funk plays a 16th-note slap line with ghost notes between the backbeats. Bebop walks the bass and puts the ride in charge of the time. Bossa runs a clave. Space strips the kit back to a pulse. Every track is built from its seed. Write the seed down and you can have that exact track again, note for note, whenever you want it. You can play over it, too. The pads are the notes of the song's key rather than a piano keyboard, so nothing you touch is wrong, and the sixteen-step lane runs in time with the song and follows your host. Both play any part you like: lead, bass, arp or pad, through that part's sound and out on its MIDI channel. Choose which sections the lane plays in - just the choruses, say - and preview it on its own without starting the song. Turn on RADIO and it keeps playing, picking a new key, mode, style and tempo for each track. You also get: • 10 styles, 6 modes, 12 keys, tempo and density • Four-operator FM engine, 6 algorithms, 11 presets, random patch • Five-part mixer, chorus, delay, plate reverb and filter • A PLAY panel: pads in the song's own key, and a 16-step lane running in time with the song and only in the sections you pick • MIDI in, so your keyboard plays whichever part you have selected • MIDI export: five tracks, one per part • Live spectrum, waveform and a view of the chaos engine at work Two Audio Units, an instrument and a MIDI processor. Each part sends on its own MIDI channel, drums on 10, so one instance can drive five instruments. The MIDI version passes your keyboard through instead of swallowing it. Both follow your host's tempo and transport. One install registers both. The app is free and nothing in it is held back. Using the Audio Units inside other apps is a one-time purchase, and each AUv3 session plays for two minutes first so you can try them properly. No account, no ads, no subscription. Works offline.
Screenshots
Verdict
REPUN and 1981 FM are too close to call on the numbers: across 5 compared parameters — price, ads, in-app purchases and device support among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.
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. REPUN sells 1 one-off in-app purchase and 1981 FM sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
| Parameter | REPUN | 1981 FM |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (3 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 3 — better |
| Update frequency | — | Every 2 weeks |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | — | Free with in-app purchases |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 16.0 | 15.0 — better |
| Further details — not scored | ||
| Size | 35 MB | 15 MB |
| Age rating | 4+ | 4+ |
| Developer | Shoma Kondo | Soft Brew Mobile |
In-app purchases
REPUN
- REPUN Full Version$6.99
1981 FM
- AUv3 Unlock$2.99









