Stem Player & Slow Downer — Support

Last updated: October 1, 2026

Thank you for using Stem Player & Slow Downer. The app runs on iPhone, iPad, and Mac. If you run into trouble, please check the FAQ below first. If your issue isn't covered, feel free to email us.

Frequently Asked Questions

Q. How do I get songs into the app?

[iPhone / iPad] Two ways. 1) From a computer on the same Wi-Fi: tap the transfer button on the top screen — the app shows an address you open in your computer's browser to send a project folder. 2) From the Files app: tap the import button and pick a folder that contains your stems.

[Mac] Just open the folder that holds your stems (from the File menu, or drag it onto the start screen). Project files (.stem) also open on a double click, and you can open music files directly too.

Q. What are "stems"?

Stems are a song split into separate parts — vocals, drums, bass, and so on. Multitrack bounces you already have can be used as they are.

Q. What is the difference between "high quality" and "standard" slow playback?

If the project contains pre-rendered slow audio, the app plays it (high quality). For speeds without pre-rendered audio, it converts in real time (standard quality). The app shows which one you are hearing whenever the speed is not x1.0.

On Mac, the app can render the high quality slow versions itself. Pick a speed and playback starts right away in standard quality while a high quality version is rendered in the background. When it is ready the app switches over and saves it, so next time it plays at high quality with no wait.

Q. Does changing the key also change the speed?

No. Key change (±6 semitones) and speed are independent — you can play two semitones down at 80% speed. Double-tap the key display (double-click on Mac) to return to the original key (0).

Q. How do I practice the same bars over and over?

Set the start with the A button and the end with the B button to loop that section. Markers (the flag button) let you jump straight back to your practice spots. On Mac you can also Shift-drag on the ruler to set the loop range.

Q. (iPhone / iPad) The screen doesn't rotate to portrait.

That's by design — the app is landscape-only so the waveforms get the full width of the screen.

Q. Do I need to buy the Mac version separately?

No. One purchase covers iPhone, iPad, and Mac. On a Mac, get it from the Mac App Store with the same Apple Account. The Mac version requires macOS 14 or later.

Q. I moved to a new device. What about my purchase?

Just download the app again from the App Store with the same Apple Account — there is no need to buy it again.

Contact

If your issue isn't covered above, please email us with your device model, OS version (iOS / iPadOS / macOS), and what happened.