Comparison

JAX MIDI ModulePlayer vs SL Knock

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

SL Knock

Features
Read full description

SL Knock is a focused AUv3 dynamics and tone effect for adding punch, body and controlled low-end weight to drums, samples and loops. • Fast controls for impact and body • Tone shaping for tighter or heavier character • Mix control for parallel processing • Factory presets and local user presets • AUv3 support for compatible iPad music hosts Works as a standalone preview app and as an AUv3 effect in GarageBand, AUM, Cubasis, BeatMaker 3 and other compatible hosts.

Screenshots

JAX MIDI ModulePlayer4 screens
SL Knock3 screens

Verdict

The call

The clearest difference is price: SL Knock at $6.99 against JAX MIDI ModulePlayer's $29.99. SL Knock also leads on update cadence (weekly vs every 6 months). On ads, in-app purchases, device support and iOS requirement 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 SL Knock $6.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

JAX MIDI ModulePlayer ships an update every 6 months, SL Knock weekly. The most recent releases landed on October 28, 2026 and October 31, 2026 respectively.

Scorecard2 real differences · 8 level
JAX MIDI ModulePlayer versus SL Knock: the parameters behind the verdict, then further details
ParameterJAX MIDI ModulePlayerSL Knock
Price$29.99$6.99 — better
Rating4.2 (5 ratings) — better—
Positive reviews50.0% of reviews—
Number of ratings5 — better—
Update frequencyEvery 6 monthsWeekly — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
DevicesiPhone, iPad, iPod, Mac — betteriPhone, iPad, iPod
Requires iOS14.0 — better15.0
Further details — not scored
Size24 MB28 MB
Age rating4+4+
DeveloperJens GuellVIACHESLAV ZHILTSOV

In-app purchases

None

JAX MIDI ModulePlayer

No in-app purchases

None

SL Knock

No in-app purchases

Questions

Is JAX MIDI ModulePlayer free?
JAX MIDI ModulePlayer costs $29.99, with no in-app purchases.
Is SL Knock free?
SL Knock costs $6.99, with no in-app purchases.
Do JAX MIDI ModulePlayer or SL Knock have ads?
Neither JAX MIDI ModulePlayer nor SL Knock shows ads.
Which is updated more often, JAX MIDI ModulePlayer or SL Knock?
JAX MIDI ModulePlayer ships an update every 6 months, and SL Knock weekly. Most recently, JAX MIDI ModulePlayer was updated on October 28, 2026 and SL Knock on October 31, 2026.

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