Repitro™ User Manual

Version 1.0 | macOS 13 or later

Repitro™ is a macOS music practice application with audio playback, precision loops, adjustable playback speed and pitch, recording, a mixer with recording effects, optional six-stem separation, MIDI automation, and project transfer. Some optional features described in this guide require external equipment or a user-provided Core ML model.

1. Getting Started

Load an audio file

1. Choose Project > Open Audio File or press Command + O.
2. Alternatively, click the folder icon in the upper-left corner, or drag an audio file into the main window.
3. The waveform appears after the audio is loaded. Select a recently loaded file from the song-title dropdown beside the folder icon when needed.
4. Select the audio output device from the upper-right dropdown or in Preferences.
5. Press Space to play.

Supported file formats are MP3, WAV, M4A, OGG, FLAC, and AIFF. Files longer than 30 minutes cannot be loaded. A previously exported Repitro™ project can also be dragged into the main window.

First practice session

Start playback, choose a difficult passage, define its loop start and end, then slow the speed as needed. You can practice playback and recording without loading a Core ML model.

2. Main Window and Playback

The main waveform shows the song and playback position, practice-loop markers, and MIDI cues. Recording clips appear in the recording track below the waveform.

Playback stops when the song reaches its end. Changes to playback speed and transpose can also be made during loop playback.

3. Precision Looping

Repitro™ stores up to 10 loops per song. The waveform shows markers for the start and end of each loop.

Create and activate a loop

1. Seek to the start of the desired passage and press [ or click the Loop Start button.
2. Seek to its end and press ] or click the Loop End button. The end point must be after the start point.
3. Press Return or click the Loop Activation button to turn looping on or off.
4. To create another loop, press + / = or click the + button, then set its boundaries.

A loop repeats when it is active and the current playback position is before its end point. Recording is disabled while a loop is active.

Select and edit loops

Loops are reordered automatically if a marker change moves one loop before another. The shortcut actions above apply to the selected loop, not every loop.

4. Metronome and Count-in

Set tempo and volume

• To adjust the tempo, drag the BPM number upward or downward. Double-click the number to reset it to the default 120 BPM.
• To set the tempo by tapping, press Tab at least twice at your desired beat interval.
• To change the beat pattern, select a time signature such as 2/4, 3/4, or 4/4 to hear accented and regular beats.
• To adjust the metronome volume, drag the volume number upward or downward. Double-click the number to reset it to the default 75.
• To stop the metronome, click the X button.
• To use the analyzed tempo of the loaded song, click Auto when available. Note that this sets the BPM only. The metronome does not automatically synchronize its beats with the song's playback.

Automatic beat analysis and count-in

Automatic beat timing depends on successful drum-stem generation and sufficiently confident beat analysis. When analysis fails or confidence is below 60%, automatic count-in is unavailable. The count-in controls let you choose the number of beats and the timing of the final beat. The count-in tempo automatically adjusts to match changes in the music playback speed.

Important: The metronome operates independently of music playback. Matching the metronome BPM to the song's tempo does not automatically synchronize the clicks with the song's beats.

5. Audio Devices and Preferences

Open Preferences to configure output, recording input and input channel, MIDI output, reduced stem level, and the recorded-clip deletion confirmation option.

Audio output

Choose the desired speakers, headphones, or compatible audio interface. Devices may appear or disappear as they are connected or disconnected.

Audio input

Choose an input device and select the correct input channel (mono or stereo as supported by the device) before recording. A wrong channel selection can produce silence or unexpected audio. Input and output devices are configured separately.

Some Bluetooth microphones or earbud input devices that would significantly degrade audio quality are automatically switched to None. This is expected behavior. A wired or USB audio interface is recommended for recording and low-latency monitoring.

Input Gain: The Input Gain control in the Mixer does not replace the hardware gain control on your audio interface. To adjust the actual input signal level, use the gain control on your audio interface or input device.

6. Audio Recording and Clips

Record a performance

1. In Preferences, select a valid audio input device and channel.
2. Deactivate any active practice loop. Recording is not available while a practice loop is active.
3. Press R or click Record to begin a take, either while playing or from a stopped position.
4. Press R or click Record again to finish the clip.
5. The recorded clip appears in the lower timeline; use the recording channel fader in the Mixer to hear it at the desired level.

If macOS requests microphone permission, allow it for Repitro™.

Manage clips

Click a recorded clip to select and highlight its boundaries. Drag the triangular handles to trim it. To remove the selected clip, press Delete or right-click and select Delete. Whether deletion requires confirmation depends on the preference setting. Deleted clips cannot be recovered.

Recorded clips are aligned to the song timeline for playback, including when playback speed or pitch settings change. Recording at slowed playback speed may produce audible degradation when later reproduced at a different speed.

Locate your recordings

Choose Open Track Saved Folder from the application menu to open the storage folder for the recorded tracks.

7. Mixer and Stem Controls

Open the Mixer window from the main player. The Mixer includes Master, Input Gain, Recording, Stem Master, and six individual stem channels.

When a user-provided Core ML model has produced stems, use the six individual faders to mix them. M mutes a channel, while D reduces it to the level configured in Preferences. The six circular stem buttons in the main window cycle through normal → reduced → muted → normal and correspond to the Mixer states. Stem Master controls the overall separated-stem level.

When no stems are available, their six faders remain disabled; the recording and other applicable Mixer controls remain usable. Changing a stem fader after newly generated stems become available can activate their per-stem meters if they initially appear inactive.

If the song is silent, check the Master and Stem Master faders, then confirm that the relevant channels are not muted.

8. Recording Effects

The recording channel offers a Compressor, 8-band Equalizer (EQ), and Reverb. Click the blue FX button beneath the recording fader to enable or bypass the full rack. Each effect also has its own on/off control.

• Compressor: Adjust Threshold, Headroom, Attack, Release, and Makeup gain. Lowering Threshold typically increases gain reduction; watch the GR meter. Makeup gain can increase the audible recording level.
• Equalizer: Adjust individual frequency-band levels to shape the recording tone.
• Reverb: Adjust room size and mix to control the simulated acoustic space and amount of effect.

To assess recording effects, balance recording and stems in the Mixer so the recorded track is audible. If a recording is unexpectedly quiet, check its fader, adjust compressor settings, or temporarily bypass the Compressor. Export options let you include or bypass recording effects.

9. Optional Core ML Stem Separation

Repitro™ supports separating music into drums, bass, vocals, guitar, piano, and other with a user-provided Core ML model. A model is not included in the app.

Set up stem separation

1. Prepare a compatible Core ML model package using resources such as the Kurtzford Audio Core ML tutorial. Models generated by following this tutorial have been verified to be compatible with Repitro™.
2. Open Preferences, choose Load Model, and select your model package.
3. Load a song and allow separation to finish. Once available, individual stems can be controlled from the main window and Mixer.
4. To stop using the model, select Unload Model in Preferences.

The Core ML package must follow the input and output specifications required by Repitro™. If loading fails, compare the model input/output shapes and data types with the app's documented requirements. If instruments appear in the wrong stem channels, verify the model's output instrument order.

Model Loading and Stem Separation Performance

Model creation, loading, and stem separation times vary significantly depending on Mac performance. The following results were obtained during testing:

Note: Model loading and stem separation run in the background, allowing you to continue using Repitro™ for music playback and practice while these operations are in progress. Actual processing times may vary depending on hardware and system conditions.

10. MIDI Control and Automation

MIDI automation sends Program Change (PC) and Control Change (CC) commands to a compatible USB-connected MIDI device at specified song positions.

1. Choose the MIDI output device in Preferences.
2. Seek to a desired timeline position and press A or click Add MIDI Action.
3. Open MIDI Controls, configure the cue's Trigger setting, and define PC or CC commands, numbers, and CC values. Add action delays when needed.
4. Start playback before the cue position to send its commands when the playhead reaches it.
5. Drag the MIDI cue tag on the waveform to adjust the trigger position.

The application supports a limited cue list (up to 10 cues). MIDI PC/CC numbers and supported values vary by device manufacturer. Refer to the device's MIDI implementation chart. Verify that your hardware supports USB MIDI command reception.

Example: Changing Presets on a Guitar Multi-Effects Processor or Amp Modeler

Many guitar multi-effects processors and amp modelers support MIDI Program Change (PC) commands to switch presets. Some devices also require Control Change (CC) commands to select a preset bank.

Repitro™ can automate these preset changes at specific positions during music playback, allowing you to switch guitar tones without manually operating your device.

Example: Switching to Preset 275 on Fender Tone Master Pro

To switch to Preset 275 on a Fender Tone Master Pro, open the MIDI Controls window in Repitro™ and configure a MIDI cue with the following settings:

• CC Number: 0
• CC Value: 2 (Bank 3)
• PC Number: 18 (0-based numbering)

When playback reaches the cue position, Repitro™ sends the Bank Select command followed by the Program Change command.

Note: MIDI commands, preset numbering, and bank selection methods vary by manufacturer and device. For the Tone Master Pro, set the MIDI Receive Channel to OMNI to accept commands from any MIDI channel. Refer to your device's MIDI implementation chart for details. Fender Tone Master Pro is a product of Fender Musical Instruments Corporation. Repitro™ is independently developed and is not affiliated with, endorsed by, or sponsored by Fender. Tone Master Pro is referenced solely as an example of MIDI device compatibility.

11. Export Audio

Open Export Audio from the app. Choose a source, format, pitch option, and whether to include recording effects, then click Export and select a destination.

Mixed with stems and Stems mix + recording tracks require separated stems and are disabled when stems are unavailable. During processing, the other application windows and the Export control are disabled to prevent conflicting actions.

12. Projects and Persistence

Each song is treated as a project. Repitro™ preserves practice configuration between sessions, including song-related loop and MIDI settings, detected tempo information, and recordings.

Export a project

Select Export Project from the top menu to bundle the original song with its loop settings, MIDI settings, automatically detected BPM, and recordings. This is different from exporting rendered audio.

Import a project

Select Import Project from the top menu, or drag a compatible project file onto the main window. Project transfer can be used to resume practice on another Mac. Confirm connected input, output, and MIDI devices after moving between computers.

Why use project export and import? If you use Repitro™ on multiple Macs, you can transfer your projects between computers and continue practicing without having to recreate loops, MIDI cues, or other practice settings.

13. Keyboard Shortcuts

Main-window keyboard controls also operate when the Mixer window has focus. For the complete current list, open Keyboard Shortcuts inside Repitro™.

14. Troubleshooting

Recording does not start

Confirm that no loop is active, a valid input device other than None is selected, and the desired input channel is configured. Check macOS microphone access if prompted.

The recording is silent, distorted, or sounds incorrect

Check the input device's channel settings. Make sure the correct physical input and mono/stereo channel are selected, and adjust hardware gain at the interface.

I cannot hear my recorded track

Check the Recording channel fader in the Mixer. If necessary, adjust the Compressor controls or bypass the Compressor to determine whether it is reducing the signal.

Where are my recordings?

Use Open Track Saved Folder from the application menu.

Changing Input Gain does not make the input louder or quieter

To change the actual physical input level, use the gain control on the connected input device or audio interface. The in-app Input Gain is not a replacement for hardware gain.

The song has no sound

Check the selected output device and Master fader; if using stems, check Stem Master. Confirm that the relevant channels are not muted.

My song sounds out of tune

Check Transpose and double-click its value to restore 0 semitones.

The Core ML model cannot be loaded

Check that its input/output tensor specifications, including shapes and data types, are compatible with Repitro™. Use the Kurtzford Audio tutorial to prepare a model.

The stem instruments are assigned incorrectly

Check the Core ML output stem order. The six output channels must correspond to the instrument mapping expected by the app.

What is a Core ML model, and how do I obtain one?

Core ML is Apple's on-device machine-learning framework. Repitro™ uses an optional, user-supplied compatible model for stem separation. See the independent Kurtzford Audio model-preparation guide.

MIDI automation does not trigger

Confirm that the correct MIDI output device is selected, the device supports USB MIDI, and PC/CC command numbers, values, and MIDI channel settings match the manufacturer's instructions.

Count-in is unavailable

Count-in needs sufficiently reliable beat detection from separated drums. It is disabled when analysis fails or beat confidence is too low.

The metronome is not in sync with the song

The correct BPM does not necessarily establish the correct beat phase. A manually set metronome tempo can run at the right speed without aligning to the song's beat positions.

My Bluetooth microphone is unavailable

Bluetooth input devices judged likely to cause significant playback-quality degradation are automatically changed to None. Use a compatible wired microphone or USB audio interface instead.

Playback or recording sounds delayed

Check the audio interface and output-device selection. Wireless devices can add latency. Prefer wired monitoring for timing-sensitive recording.

Input monitoring is not available

Repitro is designed to record audio from the selected input device without routing the incoming signal to the selected output device. To hear your instrument while playing or recording, use direct monitoring through your audio interface or source device. Changing Repitro's output device does not redirect the incoming audio to that device.

Repitro™ User Manual, Version 1.0, © 2026 Repitro™.