How to Make Slowed and Reverb on Your Phone (Android and iPhone)
A full walkthrough for Android Chrome and iOS Safari: picking the file, setting speed and reverb, where the export lands, how long it takes, and why you do not need an app.
You do not need an app to make slowed and reverb on your phone. The browser you already have, Chrome on Android or Safari on iPhone, can decode a song, run it through a speed and reverb chain, and hand you back an MP3, all without the file ever leaving the device. The slowed reverb app page explains why we built a web tool instead of a native one; the short version is that the browser already has the audio engine, and a web page cannot ask you for subscriptions or fill your lock screen with notifications.
This guide walks through the whole process twice, once on Android and once on iPhone, because the file pickers and download behaviour are different on each. It also sets honest expectations about speed. A phone is slower than a laptop at encoding, and knowing roughly how long a four-minute song takes stops you from thinking something is broken.
Before you start: get the song onto the phone
The editor works on files stored on your phone. It cannot pull a song from Spotify, Apple Music or YouTube, because those services do not give apps or websites access to the raw audio. So the first step is having an actual file: an MP3, WAV, AAC, OGG or FLAC.
Common ways people get one:
- A purchased download from Bandcamp or a store, saved to the phone.
- A file sent from a laptop by cable, AirDrop, Nearby Share or a cloud drive.
- A recording you or a friend made.
- A file from a cloud folder (Google Drive, iCloud Drive, Dropbox). On both platforms the file picker can browse these directly.
If the file is in a cloud folder, make sure it has downloaded to the device at least once, or the picker may hand the browser a placeholder that fails to decode.
Android (Chrome)
Loading the file
- Open Chrome and go to the slowed reverb maker.
- Tap the add files area. Android opens the system file picker.
- The picker usually lands on Recent. Tap the menu to switch to a specific location: Downloads, Music, your SD card, or a cloud provider such as Drive.
- Tap the song. To add several at once, long-press the first, tap the others, then Select or Open. Multi-select depends on the picker your phone ships with; Samsung's My Files and Google's Files differ slightly.
The track appears in the list and decodes. A four-minute MP3 decodes in a second or two. A long FLAC can take ten.
Setting the sound
The controls are the same as on desktop. Tap a preset to start from a sensible point:
- Haze Chamber for the heavy, dark sound.
- Wave Drift for something lighter with a longer tail.
Then adjust with the sliders. Sliders on a phone are coarse, so if you need an exact value, slide close and then nudge with small drags. Press play and the spectrum visualizer runs along the top while you listen.
For a first edit, Speed 0.85x, Reverb 40%, Space 2.8 s, Bass +5, Tone -3, Width 1.1 is a safe set of values on almost any pop or rap song.
Exporting and finding the file
Tap download. Chrome shows a progress state while the song is rendered and encoded in a web worker, then a download notification. The MP3 lands in the Downloads folder by default. Open it from the Chrome download bubble, from the Files app under Downloads, or from your music player if it scans that folder.
If you exported several tracks, you get a ZIP. Android's Files app can open ZIPs natively; tap it, then extract.
Time expectations on Android
| Device | 4-minute song, single export | 10-song ZIP |
|---|---|---|
| Recent flagship (2024 or newer) | 10 to 25 seconds | 2 to 4 minutes |
| Mid-range from the last three years | 25 to 60 seconds | 4 to 8 minutes |
| Budget or older than 2020 | 1 to 3 minutes | 10 minutes or more |
These are rough, from testing on a handful of phones, not a benchmark. Keep the screen on while it works. Android may throttle a background tab, and a locked screen pauses the worker on some phones.
iPhone and iPad (Safari)
Loading the file
- Open Safari and go to the slowed reverb for iPhone page or the main editor.
- Tap the add files area. iOS asks where the file is: Photo Library, Take Photo or Video, or Choose File. Pick Choose File.
- The Files browser opens. Your song may be under On My iPhone, iCloud Drive, or a connected provider like Dropbox. Downloads from Safari go to iCloud Drive/Downloads by default unless you changed it in Settings.
- Tap the file. For several tracks, tap Select in the top corner, choose each file, then Open.
Songs in the Apple Music app are not available to Safari, even ones you purchased, because the Music library is not exposed as files. Use a file you downloaded or transferred.
Setting the sound
Identical controls to Android and desktop. One iOS-specific point: Safari will not start audio until you tap play. That is a browser rule, not a bug. Tap play once, and from then on the sliders respond live.
If you are on an iPad, the layout widens and the controls behave like the desktop version.
Exporting and finding the file
Tap download. Safari shows a download arrow icon in the address bar. When the encode finishes, tap that icon to see the file. By default it is saved to iCloud Drive/Downloads, or On My iPhone/Downloads if you changed the Safari download location in Settings, Safari, Downloads.
From the Files app you can play the MP3, share it to another app, or save it to a cloud folder. ZIPs can be unpacked by tapping them in Files.
Time expectations on iOS
Recent iPhones are fast at this. A four-minute track typically exports in 10 to 30 seconds on a phone from the last few years, and an iPad with a laptop-class chip is quicker than many laptops. Older iPhones take a minute or two per song. As on Android, keep Safari in the foreground until the download arrow appears.
Settings that work on a phone speaker
Edits are usually made on headphones and then heard on speakers. Phones have almost no bass below 150 Hz and a peak in the upper mids, so an edit tuned on headphones can sound thin or harsh when played back on the device itself. If you know your audience will listen on phones, which is nearly everyone on TikTok, bias your settings toward this table.
| Control | Headphone-first setting | Phone-speaker-friendly setting | Why |
|---|---|---|---|
| Speed | 0.80x to 0.85x | 0.85x to 0.88x | A slightly faster speed keeps the vocal in the range phone speakers reproduce |
| Reverb | 45 to 55% | 30 to 40% | Small speakers blur a wet mix into noise |
| Space | 3.0 to 4.0 s | 2.4 to 3.0 s | Shorter tails stay clear on a mono speaker |
| Bass | +6 to +8 | +3 to +5 | Phone speakers cannot play it, and the boost only eats headroom |
| Tone | -4 to -6 | -2 to -3 | Too dark on a speaker that is already weak in the highs |
| Width | 1.1 to 1.3 | 1.0 | Phone speakers are mono; width does nothing useful |
Export once, play it back through the phone speaker, then adjust and export again. Two passes is normal.
Doing several songs at once
Both platforms support multi-select in the file picker, and the editor treats the batch the same way the desktop does. Select All Tracks, set the controls once, and Download All gives a ZIP. If you want different settings for one track, tap Clear Selection, select just that track, and change it. The bulk slowed reverb page goes into that workflow.
Be realistic about batch size on a phone. Ten songs on a mid-range Android is several minutes of encoding with the screen on. If you have a laptop available, do large batches there and keep the phone for one-offs.
Why a web page and not an app
A fair question, since app stores are full of slowed reverb apps. The reasons we went with the browser:
- Nothing is uploaded. The Web Audio API decodes and processes the file on the device. There is no server to send the song to and no server to lose it from.
- No permissions. The page does not ask for storage, microphone or notification access. The file picker is the only way it touches your files.
- Same tool everywhere. The edit you make on your phone uses the same chain as the desktop export. Presets you save are stored in the browser on that device.
- No subscription screens. Free, no account, no watermark, no limit on file count or length.
The trade-offs are real too. A native app could encode faster and run in the background. It could also export WAV, which this tool does not; output is MP3 at 96 kbps, 32 kHz. For posting to TikTok, YouTube and Shorts that is enough, because the platforms re-encode what you upload. For a lossless master you need a desktop DAW.
Troubleshooting
The file picker does not show my song. On iOS, songs inside the Music app are not visible to Safari. On Android, a song inside a streaming app's cache is not a file you can pick. You need a real downloaded file.
It decoded but will not play. On iOS, tap play once; Safari needs a user tap to start audio. On Android, check the phone is not on silent with media volume at zero.
The export seems stuck. Keep the browser in the foreground and the screen on. Switching apps mid-encode can pause the worker. If the progress has not moved in two minutes on a long track, reload and try again with that one file.
The download is nowhere. Android: Chrome menu, Downloads. iOS: the download arrow in Safari's address bar, then Files app, Downloads folder.
The MP3 sounds different from the preview. With Preserve pitch off it should not; the export uses the same chain. With Preserve pitch on, the export keeps the speed-linked pitch, so it will sound lower or higher than the preview. Otherwise, check you are not comparing a headphone preview with a speaker playback.
Reverb sounds choppy during preview. Older phones can struggle to run the convolution reverb live. The export is rendered offline and will be clean even if the preview stutters.
Open the free editor: upload MP3, WAV, AAC, OGG or FLAC, adjust speed, reverb, bass, tone, width and space, then export MP3 or a ZIP of many tracks. Everything runs in your browser.
Frequently asked questions
Do I need to install an app to make slowed and reverb on my phone?
No. Chrome on Android or Safari on iOS runs the editor in the browser, and the finished MP3 downloads to your phone.
Where does the exported file go?
Android: the Downloads folder, reachable from Chrome's download list or the Files app. iPhone: the Downloads folder in Files, usually under iCloud Drive, reachable from the download arrow in Safari.
Can I use a song from Spotify or Apple Music?
No. Streaming apps do not expose their audio as files. You need an MP3, WAV, AAC, OGG or FLAC saved on your device.
How long does it take on a phone?
Roughly 10 to 60 seconds for a four-minute song on a recent phone, a few minutes on an older one. Batches scale with the number of tracks.
Is the quality the same as on a computer?
Yes. The processing chain and the MP3 encoder are identical. Only the time it takes differs.
Does the page upload my music anywhere?
No. Decoding, processing and encoding all happen on the phone. Nothing leaves the device.
Can I save my settings on my phone?
Yes. The Create preset button stores a custom preset in the browser's local storage on that phone. It does not sync to other devices.