SL Knock vs Tracker Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SL Knock
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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.
Tracker Pro
Create music with samples, synthesizers, and Audio Unit plugins within a pattern grid. Arrange patterns into songs, shape sounds with commands, and utilize touch, keyboard, or MIDI input. Includes built-in sounds and a demo to get started.
- Pattern grid for music creation
- Integrated samplers and synthesizers
- Audio Unit (AUv3) plugin hosting
- Advanced step sequencing with commands
- Song arrangement and structure
- Multiple input methods (touch, keyboard, MIDI)
- Export mixes and individual stems
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Tracker Pro puts samples, synthesizers, Audio Unit plug-ins and MIDI gear in one pattern grid. Write drums, bass lines and chords, shape each step with commands, and arrange your patterns into a finished song. Use touch controls, hardware-keyboard shortcuts or MIDI note input. On Mac, the same workspace also supports a keyboard and pointer. Built-in sounds and the STARTER 148 demo let you begin without extra equipment or downloads. TRACKER • Up to 16 tracks and patterns up to 128 rows, with independent track lengths for polymeter • Up to 8 FX slots per step for retriggers, chance, glide, sample start, slices and more • Chords of up to 6 notes, note tables, swing and grooves • 8 macros and 12 automation lanes per track • Song arrangement with sections, repeats and live row cueing • Piano roll editing, undo, copy and paste SAMPLER • Keep a whole kit in one Sampler: load files or a folder and choose the sample for each note • Random sample and slice selection for patterns that change as they play • Slice by transient, beat grid or hand, with up to 48 slices • Modern, Amiga, M3000 and SP12 playback modes, with editable bit depth, sample rate and interpolation • Stretch loops to fit bars, reverse playback and build crossfaded loops • Morphing filters with envelope, LFO, velocity and note modulation • Record the microphone, an audio interface, a track, a return bus or the master • Import audio files or extract sound from a video • Sample Crate: collect sounds from the web, your files and videos SYNTHESIZERS • Macro: 24 engines for basses, chords, percussion and evolving tones • VintagePoly: two-oscillator polyphonic synthesis with programmable modulation • VintagePD: phase-distortion synthesis with detailed multi-stage envelopes • VintageSub: subtractive synthesis with oscillator mixing, filter drive and modulation • Resonator: modal and string physical models • GrainOSC: pitched grain textures from built-in wavetable banks EFFECTS AND MIXING • EQP1 program EQ, Saturation, Tape and Vinyl for tone, drive and texture • Gate/Exp and Transient Designer for dynamics and attack • Granular FX, Ambient Reverb, Space, Delay, Lofi, Compressor and more • Put effects on tracks, two return buses and the master • Save presets and automate the controls PLUG-INS AND MIDI • Host compatible Audio Unit instruments and effects; presets and plug-in state save with the project • MIDI Out with notes, chords, bank and program changes, and 16 control lanes • MIDI input over USB, Bluetooth and virtual ports FINISH AND SHARE • Bounce a track’s current pattern and effects into a new Sampler instrument • Export WAV mixes and individual track stems • Self-contained projects with autosave and crash recovery • Transfer projects between iPhone, iPad and Mac; third-party plug-ins must be available on the destination device GOOD TO KNOW • iPhone, including iPhone Duo, and iPad: iOS/iPadOS 17 or later • One purchase covers iPhone, iPad and Mac • The compatible iPad app also runs on Apple Vision Pro • No account, subscription, ads or in-app purchases Documentation and tutorials: https://www.dubspot.com/tracker-pro/guide Support: https://www.dubspot.com/tracker-pro/support Includes open-source Plaits, Rings and Beads DSP by Emilie Gillet under the MIT License. Mutable Instruments is not affiliated with Dubspot.
Screenshots
Verdict
The clearest difference is price: SL Knock at $6.99 against Tracker Pro's $14.99. SL Knock also leads on iOS requirement (15.0 vs 17.0). On update cadence, 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
SL Knock costs $6.99 and Tracker Pro $14.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Both ship on a similar rhythm, roughly weekly. The most recent releases landed on November 10, 2026 and November 14, 2026 respectively.
| Parameter | SL Knock | Tracker Pro |
|---|---|---|
| Price | $6.99 — better | $14.99 |
| Rating | — | 5.0 (1 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 1 — better |
| Update frequency | Weekly | Weekly |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 29 MB | 47 MB |
| Age rating | 4+ | 17+ |
| Developer | VIACHESLAV ZHILTSOV | Dubspot |
In-app purchases
SL Knock
No in-app purchases
Tracker Pro
No in-app purchases









