Comparison

SL Knock vs Tracker Pro

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

Head to head
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.

About

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.

Highlights
  • 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
Features
Read full description

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

SL Knock3 screens
Tracker Pro4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly weekly. The most recent releases landed on November 10, 2026 and November 14, 2026 respectively.

Scorecard2 real differences · 8 level
SL Knock versus Tracker Pro: the parameters behind the verdict, then further details
ParameterSL KnockTracker 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 frequencyWeeklyWeekly
AdsNoNo
In-app purchasesNoNo
Monetization—Paid
DevicesiPhone, iPad, iPodiPhone, iPad, Mac
Requires iOS15.0 — better17.0
Further details — not scored
Size29 MB47 MB
Age rating4+17+
DeveloperVIACHESLAV ZHILTSOVDubspot

In-app purchases

None

SL Knock

No in-app purchases

None

Tracker Pro

No in-app purchases

Questions

Is SL Knock free?
SL Knock costs $6.99, with no in-app purchases.
Is Tracker Pro free?
Tracker Pro costs $14.99, with no in-app purchases.
Do SL Knock or Tracker Pro have ads?
Neither SL Knock nor Tracker Pro shows ads.
Which is updated more often, SL Knock or Tracker Pro?
SL Knock ships an update weekly, and Tracker Pro weekly. Most recently, SL Knock was updated on November 10, 2026 and Tracker Pro on November 14, 2026.

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