Turn an MP3 into slowed + reverb
Drop the file in, move three sliders, export. It runs in the browser on your own machine, so it is free, unlimited, and your audio never leaves your device.
The steps
- Load the MP3. Drop it onto the page or pick it from your device. Nothing uploads, so a long track opens as fast as a short one.
- Set the speed first, alone. Start at 0.90×. Speed on its own decides whether the track still holds together — add effects before you have settled it and you will not know what caused what.
- Then reverb, 12 to 18 %. Raise it gradually. Past 25 % the words start to blur.
- Then bass, 8 to 15 %. Slowing thins the low end. This puts it back.
- Listen on the speaker you expect people to use. Phone speakers hide reverb and eat bass; headphones flatter both.
- Export. MP3 to publish, WAV or FLAC if the file goes into a video editor.
Free, and why it can be
Converting a file from your own device costs nothing, has no limit and needs no account. That is not a trial or an introductory offer: the effects are computed by your browser through the Web Audio API, and the export is encoded on your machine as well. Your file is never sent anywhere, so there is no server bill to pass on and nothing to ration.
One mode is paid, and it is worth being plain about which: converting straight from a YouTube link runs on a server, because the track has to be fetched and decoded before you hear anything. That access costs €2.99 for seven days or €19.99 for a year, paid once, with no subscription. Everything on this page — your own MP3 — stays free.
What goes in, what comes out
MP3 and WAV are the common cases, but the converter also takes FLAC, M4A, AAC, OGG, Opus, AIFF, WMA and a long tail of older formats. If your file plays on your computer, it will almost certainly load.
Exports come out as MP3, WAV or FLAC. MP3 for anything you publish or send; WAV or FLAC when the file is going into a video editor and will be re-encoded afterwards anyway.
One thing worth knowing: an MP3 is already a lossy file. Slowing it and re-exporting to MP3 encodes it a second time. The loss is small at a decent bitrate, but if you have the original WAV or FLAC, start from that instead.
Settings that work, by genre
Tracks do not respond equally. A sparse mix takes reverb well; a dense one turns to soup.
| Genre | Speed | Reverb | Bass boost |
|---|---|---|---|
| R&B | 0.86× – 0.90× | 16 – 22 % | 12 – 18 % |
| Pop | 0.88× – 0.92× | 14 – 18 % | 10 – 15 % |
| Rap | 0.88× – 0.93× | 10 – 15 % | 15 – 20 % |
| Ballad / piano | 0.85× – 0.90× | 18 – 25 % | 5 – 10 % |
| Rock | 0.90× – 0.94× | 8 – 12 % | 8 – 12 % |
Slowed, slowed + reverb, nightcore, sped up
Four names, two dials. Slowed lowers the playback speed and nothing else. Slowed + reverb adds reverberation on top, which is what gives the style its room-at-3am feel. Sped up raises the speed. Nightcore raises the speed and the pitch with it, which is why voices come out bright and cartoonish rather than merely quick.
All four start from the same file and the same sliders. If you are not sure which one you want, make the slowed version first and listen: the reverb decision is much easier once the tempo is settled.
What it will not do
It will not rescue a bad source. A track already compressed to death does not improve by being slowed; it just becomes a slower version of the same problem.
It will not separate the vocal from the instrumental. That is a different operation and a different kind of tool.
And it will not settle the rights question for you. A slowed version is a derivative work: the original rights still apply, and platforms detect it by fingerprint. For private listening this is moot. For publishing, check the source.
Frequently asked questions
How do you make an MP3 slowed and reverb?
Load the file, set the speed to about 0.90×, add 15 % reverb and 12 % bass boost, then export. Set the speed on its own first — the reverb amount that sounds right depends on the tempo you land on.
Is it free?
Yes, for a file from your own device: free, unlimited, no account. The effects run in your browser, so there is nothing to meter. Only the YouTube link mode is paid, because it is the only one that uses a server.
Is my MP3 uploaded anywhere?
No. The file is read and processed locally and the export is encoded locally too. Your audio never leaves your machine — which is also why the conversion starts instantly instead of waiting on an upload.
What speed makes a track sound slowed?
Between 0.85× and 0.92×. Below 0.80× most tracks smear and the vocal loses its consonants; above 0.95× the change is barely audible.
Does it work on a phone?
Yes, in the mobile browser, with nothing to install. Check the result on the phone speaker rather than headphones — that is how most people will hear it.
Can I publish the result?
A slowed version is a derivative work. The rights on the original track still apply and platforms identify it by audio fingerprint. For anything beyond private listening, check the rights on the source.