Comparison

JAX MIDI ModulePlayer vs ThereminAir

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

JAX MIDI ModulePlayer

This app functions as a General MIDI compatible multi-timbre synthesizer and file player. It can be used as a sound module for external MIDI signals or as an audio unit within compatible host applications. Create and play back standard MIDI files with over 370 instruments and drum sets.

Highlights
  • GM/GS compatible synthesizer
  • Plays standard MIDI files
  • Over 370 instruments and drum sets
  • 16 MIDI channels simultaneously
  • Audio Unit (AUv3) support
  • Standalone host functionality
  • Universal app for Apple devices
Features
Read full description

There is a manual at: https://midi.digitster.com/JAX%20MIDI/JAX%20MIDI%20ModulePlayer.pdf And a demonstration video at: https://youtu.be/DKwRxcfgy8s JAX MIDI Module & Player can be used as a GM/GS (General MIDI) compatible multi-timbre synthesizer for playing live or as a file player. It is usable as a sound module for external MIDI signals and as audio unit for usage in any host application, which supports Apples AUv3 format. With JAX MIDI Module & Player you can load available standard MIDI files and just play them back. It has inbuilt a fully featured GM/GS synthesizer with over 370 different instruments and drum sets, which is also playable in realtime on 16 MIDI channels simultaneously. The module works like the classic external hardware modules of the late 90s. If used as an audio unit, the MIDI stream is passed thru, so that other apps (like synthesizers and drum machines) can profit from the file playback. Internal sound generation can muted with the main volume slider. Important GM MIDI controllers are supported and also displayed for overview. The playing state of all channels is displayed in realtime. For JAX MIDI Module & Player, you may create your own MIDI files with notes with any external MIDI editor that can create standard MIDI files format 0 or 1, with controllers and tempo changes and all and then play back thru it with the internal or any external instrumentation. AudioUnits (AUv3) require a supporting host application to perform. But our app is able to perform as a standalone host for the embedded unit and provide basic Core MIDI functionality for communicating outside the sandbox. This build is truly 'universal', meaning, the unit is available for: - MacOS (Silicon M1) - iOS (iPhone) - iPadOS (iPads) Note: We now will separate the native macOS release (Mac Catalyst) from the iOS universal release, because native macOS releases need special optimizations. There also will be different prices for the native macOS apps. Making AUv3 technology available across all devices (for usage with GarageBand, Logic Pro X, MainStage 3 on the Mac), is quite a challenge. And we have chosen to deliver the releases across all devices instead of asking multiple times for money. Our builds come with latest technology support for all Apple devices (at the point of release). We therefore always develop with latest Apple frameworks and compilers. But we try to keep the compatibility at minimum requirements as far as even possible. Especially the latest M1/2/3 and cross platform optimizations forced us to drop all the legacy device support (below iOS 14). This is also true for all our older apps, which will be updated step by step to reflect the latest technologies.

About

ThereminAir

This app transforms your Apple Watch into a unique theremin instrument. Play music through arm gestures, controlling pitch and volume without touching any buttons. Explore different modes and scales to create a variety of sounds.

Highlights
  • Gesture-based pitch and volume control
  • Pure mode for continuous glide
  • Scale modes for staying in tune
  • Adjustable pitch ranges and vibrato depths
  • Live readout of frequency and note name
  • Complication for instant play
Features
Read full description

ThereminAir turns your Apple Watch into a theremin — the legendary instrument you play without ever touching it. Anchor your elbow and sweep your forearm like the hand of a clock: raise it and the pitch rises, lower it and the pitch falls. Rotate your wrist to swell the volume. There are no buttons to press while you play, no strings, no keys — just the motion of your arm in the air, exactly like the real thing. Your arm becomes the antenna. HOW IT WORKS • Sweep your forearm for pitch — glide smoothly or lock to musical notes • Rotate your wrist for volume — from a whisper to full voice • Wobble your wrist on a held note and it sings with real vibrato • Turn the Digital Crown to set your maximum volume • Watch the live readout — frequency, note name, and a scrolling trace of your vibrato PLAY IN KEY Pure mode gives you the classic continuous theremin glide. Prefer to stay in tune? Choose a scale and every note snaps to it: • Major and Minor • Major and Minor Pentatonic • Pick any root note Vibrato sings around the note you land on, so playing in key never sounds locked to a grid. MAKE IT YOURS • Three pitch ranges — Precise for playing in tune, Standard for everyday play, Wide for drama • Three vibrato depths — Subtle, Natural, Wide • The tone brightens as you play louder, the way an acoustic instrument does • Plays the right way round on either wrist, in either crown orientation • Vibrato-only mode, so travelling to a new note stays clean RECOMMENDED SETTINGS Precise range · Pure scale · Dynamic timbre on · Wide vibrato depth · Vibrato only on · Travel-proof vibrato off · Exclusive audio off TAP AND PLAY Add the ThereminAir complication to your watch face and a single tap launches you straight into play mode — no menus, no waiting. Or just say "Hey Siri, play ThereminAir". BUILT FOR THE WATCH • Smooth, low-latency synthesis tuned for Apple Watch • Clean, glanceable interface • Works on the go — your instrument is always on your wrist Whether you're making eerie sci-fi sweeps, practicing pitch, or just playing with sound while you wait for coffee, ThereminAir puts a real instrument on your wrist.

Screenshots

JAX MIDI ModulePlayer4 screens

Verdict

The call

The clearest difference is price: ThereminAir at $3.99 against JAX MIDI ModulePlayer's $29.99. ThereminAir also leads on rating (5.0 vs 4.2) and update cadence (every 11 days vs every 6 months). JAX MIDI ModulePlayer's advantage is ratings volume (5 vs 1) and iOS requirement (14.0 vs 17.0). On 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

CostPrice · In-app purchases · Ads · Monetization

JAX MIDI ModulePlayer costs $29.99 and ThereminAir $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

ThereminAir holds the better App Store score, 5.0 against 4.2. That said, the two scores are not equally well evidenced: JAX MIDI ModulePlayer has 5 ratings behind it against 1, so its average is the more settled of the two.

UpkeepUpdate frequency

JAX MIDI ModulePlayer ships an update every 6 months, ThereminAir every 11 days. The most recent releases landed on October 19, 2026 and October 11, 2026 respectively.

Scorecard6 real differences · 4 level
JAX MIDI ModulePlayer versus ThereminAir: the parameters behind the verdict, then further details
ParameterJAX MIDI ModulePlayerThereminAir
Price$29.99$3.99 — better
Rating4.2 (5 ratings)5.0 (1 ratings) — better
Positive reviews50.0% of reviews—
Number of ratings5 — better1
Update frequencyEvery 6 monthsEvery 11 days — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad, iPod, Mac — betteriPhone, iPad, Apple Watch
Requires iOS14.0 — better17.0
Further details — not scored
Size24 MB2 MB
Age rating4+4+
DeveloperJens GuellTom Pardee

Customer experience

JAX MIDI ModulePlayer

All ratings5 ratings
Positive80.0%
Neutral0.0%
Negative20.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

ThereminAir

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

JAX MIDI ModulePlayer

No in-app purchases

None

ThereminAir

No in-app purchases

Questions

Is JAX MIDI ModulePlayer free?
JAX MIDI ModulePlayer costs $29.99, with no in-app purchases.
Is ThereminAir free?
ThereminAir costs $3.99, with no in-app purchases.
Which has better reviews, JAX MIDI ModulePlayer or ThereminAir?
ThereminAir is rated higher. JAX MIDI ModulePlayer averages 4.2 out of 5 from 5 ratings, while ThereminAir averages 5.0 from 1 ratings.
Do JAX MIDI ModulePlayer or ThereminAir have ads?
Neither JAX MIDI ModulePlayer nor ThereminAir shows ads.
Which is updated more often, JAX MIDI ModulePlayer or ThereminAir?
JAX MIDI ModulePlayer ships an update every 6 months, and ThereminAir every 11 days. Most recently, JAX MIDI ModulePlayer was updated on October 19, 2026 and ThereminAir on October 11, 2026.

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