Speldosa vs RingsFX
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Speldosa
This digital instrument plugin recreates the enchanting sound of a music box, offering four distinct sonic characters and two room ambiences. It's designed to inspire immediate melody creation and can be used as a standalone app or an AUv3 plugin.
- Four music box sound models
- Two room ambiences
- Algorithmic reverb
- Optional vibrato
- Standalone app and AUv3 plugin
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Speldosa (Wintergatan Music Box) is an Audio Unit instrument, the result of a unique collaboration between Klevgrand and the Swedish artist Wintergatan/Martin Molin. Wintergatan has primarily worked in the physical world (the Marble Machine is probably the most astonishing example), while Klevgrand has performed its craft within the digital sphere. When these two worlds now meet, the result is something that both visually and aurally inspires the creation of new compelling melodies. Speldosa (Swedish for “Music Box”) is the essence of the shared beliefs of Klevgrand and Wintergatan, and their fascination with minimalism. A simple melody played on a music box can contain an equal amount of emotional power as any symphonic work. There is something about the music box sound that never ceases to fascinate. The instrument itself has been meticulously recorded by Wintergatan and transformed into a playable digital instrument plugin. It features four different models (Modern, Vintage, Antique, and Eternal = Reversed), two different Room models, and an algorithmic reverb. Wintergatan about Speldosa: "I created the sound by sampling a music box using an acoustic guitar as resonance box. I chose the best samples and it was instant magic. The Music Box went on to become the sonic signature for my two bands, Detektivbyrån and Wintergatan, both recognised for their unique sound. The Speldosa has been the secret sauce in my music career and i hope other musicians finds it as useful as i have. There is a special quality to this exact music box sound that lifts it above the novelty feeling of a toy and turns it into a real music instrument. It just sounds so good, that’s really it. And it is a sound that makes you write music instantly - the music comes from the sound itself. During the collaboration with Klevgrand, when they sent me the first beta version of the plugin, i ended up playing around with the sound for three hours, losing track of time. I wrote three songs that day when i was scheduled to actually do something else. That’s what the sound does to me, and i think it will do the same for others." Features: - Four different music box characters - Two room ambiences - Spacious reverb - Optional vibrato - Output level Speldosa works both as a standalone app and as an AUv3 plugin. Check out the product web page for more info, sound examples and a user manual. Feedback or suggestions? Drop us a mail: support(at)klevgrand.se or @klevgrand on Twitter.
RingsFX
This music app emulates a renowned physical modeling synthesizer, offering diverse synthesis techniques and polyphonic capabilities. It allows for real-time parameter manipulation and can process external audio, creating unique sonic textures and rhythms.
- Physical modeling synthesis emulation
- Multiple polyphony modes (Mono, Duo, Quad, True Polyphonic)
- Supports MIDI MPE and velocity sensitivity
- External audio excitation
- Mod Matrix for real-time parameter control
- 7 unique synthesis modes
- 6 mod-able and 6 global effects
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RingsFX is an AUv3 plugin based on the famous Mutable Instruments Rings, one of the most dedicated and fully-featured Physical Modeling Eurorack modules ever created. At its core is a resonator that needs to be 'excited' or 'strummed' by MIDI input, noise, or external audio excitation. RingsFX emulates vibrations of structures simulated by 3 different synthesis techniques that can be plucked or process external signals: Modal Synthesis, Sympathetic Strings, and Inharmonic Strings. Traditionally, Rings was only monophonic but used a unique approach to polyphony that allowed the previous note to 'ring' out and decay while a new note was played. Rings FX provides these same modes (Mono, Duo, and Quad), but expands it with a true Polyphonic mode. RingsFX also expands the capabilities of the original engine by adding support for velocity sensitivity and MIDI MPE mode. The new polyphonic mode allows RingsFX to play up to 12 notes of true polyphony, depending on the settings. Doing so requires RingsFX to use multiple Rings resonators, but the more true polyphony you use, the more processing power it requires. Running in the traditional Monophonic, Duophonic, or Quadrophonic modes may be preferred in order to keep CPU usage under control. RingsFX has 7 modes in total, by combining the 3 basic modes with additional properties such as chords or specially tuned reverbs. The original hardware also had a secret 'Easter Egg' mode, which in RingsFX is simply calling 'Synthesizer' mode, rumoured to be based on one of the early Korg synthesis methods. This mode supported a number of mutable effects which now work on in all resonator modes. RingsFX also has a Mod-Matrix which allows you to combine the built-in LFOs and FEGs to great effect by manipulating parameters and mutable effects in realtime. Finally, RingsFX can be loaded as an AUv3 effect plugin. Set the Exciter Source to 'INPUT', and you can pass any audio through RingsFX and use this audio as an external exciter. For example, it can be used to great affect on a drum beat to create some crazy rhythms. Use the Output Mix to combine the original audio with the synthesised resonator output to create some stunning effects. Features ○ 7 unique synthesis modes. ○ Supports Mono, Duo, Quad and true polyphony. ○ Supports 2 fluid LFO's per note. ○ Up to 4 FEG's per note. ○ External Exciter modes. ○ White noise Pulse Sequencer. ○ Supports 6 mod-able effects and 6 global effects. ○ Mod Matrix ○ Input and white noise filters. ○ Program Manager with drag and drop. ○ Preset Search and Favourites. ○ Easy export and import of banks and presets. ○ Extensive help manual. ○ Web Transfer for backing up to PC/Mac. ○ MPE Support.
Screenshots
Verdict
The clearest difference is update cadence: RingsFX at fortnightly against Speldosa's every 10 months. RingsFX also leads on review sentiment (100% vs 72%) and price ($7.99 vs $9.99). On rating, ratings volume, ads and in-app purchases 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
Speldosa costs $9.99 and RingsFX $7.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.8 for Speldosa against 4.9 for RingsFX. Both are backed by a comparable volume of ratings — 28 and 26 respectively. Written reviews are what separate them: 72% of Speldosa's written reviews are positive against 100% of RingsFX's.
Speldosa ships an update every 10 months, RingsFX fortnightly. The most recent releases landed on September 22, 2026 and September 21, 2026 respectively.
| Parameter | Speldosa | RingsFX |
|---|---|---|
| Price | $9.99 | $7.99 — better |
| Rating | 4.8 (28 ratings) | 4.9 (26 ratings) — better |
| Positive reviews | 72.4% of reviews | 100.0% of reviews — better |
| Number of ratings | 28 — better | 26 |
| Update frequency | Every 10 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 | 13.0 |
| Further details — not scored | ||
| Size | 15 MB | 23 MB |
| Age rating | 4+ | 4+ |
| Developer | Klevgrand Produkter AB | 4Pockets.com |
Customer experience
Speldosa
RingsFX
In-app purchases
Speldosa
No in-app purchases
RingsFX
No in-app purchases








