Control

Preserve Pitch

Preserve pitch keeps the original key while speed changes. See how browser time-stretch works, when to use it, its artifacts, and why slowed edits leave it off.

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.

Preserve pitch is the only switch among the sliders. It is off by default, and in that state the editor behaves like a turntable: slow the song down and the pitch drops, speed it up and the pitch rises. Turn it on and the song keeps its original key while the tempo changes. That sounds like a strict upgrade. It is not. It is a different tool for a different job, and for the classic slowed + reverb sound it is the wrong one. This page explains what the toggle does, when it helps, what it costs at extreme speeds, and how to decide for a given track in the slowed reverb maker.

Preview only: read this before you export

Preserve pitch applies to the live preview in the editor. It tells the browser to keep the key while you listen at a new speed. The export path is different: it renders the track at the chosen playback rate and does not use the toggle, so exported MP3s currently follow speed-linked pitch. A 0.85x export is about 3 semitones lower than the original whether Preserve pitch is on or off. With the toggle on, what you hear in the preview is not what lands in the file.

If you need a slower or faster file in the original key, process it outside the editor:

1. Open the song in Audacity (free). Select all with Ctrl+A.
2. Go to Effect, then Pitch and Tempo, then Change Tempo. Enter the percent change (-15 for 0.85x, +25 for 1.25x) or type the new length. Tick "Use high quality stretching" and apply.
3. Export with File, Export Audio, as WAV or MP3 at the bitrate you want.

Any DAW with a time-stretch mode (Reaper, Ableton Live, FL Studio, Logic) does the same job: set the clip to a pitch-preserving stretch mode and change the tempo or clip length. Use the editor here to audition speeds with the toggle on, then make the final in-key file in one of those tools.

What Preserve pitch does

With the toggle off, changing Speed changes the playback rate of the audio. The samples are read faster or slower and every frequency moves with them. At 0.85x everything is about 2.8 semitones lower. At 1.30x everything is about 4.5 semitones higher. Tempo and pitch are locked, exactly as on tape or vinyl.

With the toggle on, the editor asks the browser to time-stretch the audio instead. Time-stretching changes the duration of a sound without changing its pitch. The browser does this with its built-in pitch-preserving playback, the same mechanism that keeps voices at their normal pitch when you set a video player to 1.5x. The song plays slower or faster and stays in its original key.

Note what the toggle cannot do. It changes tempo without changing pitch, but there is no mode that changes pitch without changing tempo. If you want to lower the pitch of a song the only route in this editor is slowing it with the toggle off.

Why the classic slowed sound needs it off

Slowed + reverb is not just a tempo change. The lowered pitch is at least half of the effect:

• The voice drops into a lower register. A singer who was bright and forward becomes warm and close. A rapper's voice gains weight. This is the single most recognisable feature of the style, and it is the pitch, not the tempo.
• The whole mix shifts down. Kick, bass, pads and guitars all move about three semitones lower at 0.85x, which reads as heavier and darker before you touch the Bass or Tone sliders.
• The transients soften naturally. With the toggle off, slowing stretches every attack. The drums hit softer in a way that sounds organic.

Turn the toggle on and you keep the tempo change but lose all three. The song is slower but sounds like the same recording played slowly, not like a slowed edit. Listeners who know the style will notice immediately. Every built-in preset, including Haze Chamber and Wave Drift, ships with Preserve pitch off for this reason.

When to turn it on

Preserve pitch is for cases where the tempo is the goal and the key must not move. All of these are preview uses in the current editor: you can audition the right speed with the key held, but the exported file will carry the speed-linked pitch, so make the final in-key file in Audacity or a DAW as described above.

• Practice and learning. Slowing a song to 0.75x to work out a guitar part or a vocal line, while staying in the key you will play it in.
• Dance and choreography. Rehearsing a routine at 0.85x and gradually bringing it up to full speed, without the music changing key between runs.
• Speech, podcasts and lectures. Speeding up at 1.30x to 1.50x while keeping voices natural.
• A singer whose voice goes too low. If a slowed edit at 0.85x pushes a vocal below what sounds natural, Preserve pitch keeps the voice in place while you still get the slower tempo. You lose the classic colour, but the song survives.
• Tempo-matching for a mix or mashup. Nudging a track from 128 to 124 BPM without a key change.
• Sped up edits that must stay in key. For singers with low voices, 1.25x with Preserve pitch on keeps the energy without the cartoon register.

The blog post on how to slow down a song without changing pitch walks through the practice-track use in detail.

Artifacts at extreme speeds

Time-stretching is an estimate. The browser has to invent or remove material to change the duration without changing the pitch, and the further from 1.00x you go, the more it has to invent. The side effects are predictable:

• Warble or flutter. Sustained notes and vocals acquire a slight wobble, most audible on long vowels and on pads.
• Phasiness. A hollow, swirling quality in the upper mids, especially on dense mixes with lots of overlapping harmonics.
• Smeared transients. Drum hits lose their edge. Snares get a soft pre-echo and hi-hats turn mushy.
• Doubled or stuttered consonants. At slow speeds, short sounds like "t" and "k" can seem to repeat.

The honest advice is to stay between 0.75x and 1.35x with the toggle on. Beyond that, compare both modes and pick whichever sounds less broken for your source. Sparse material with one voice and a simple beat stretches far better than a dense wall of guitars.

A negative Tone of -2 to -4 dB hides a good deal of time-stretch phasiness, because the artifacts live mostly above 2 kHz.

How Preserve pitch interacts with the other controls

Speed. Obviously. The toggle changes what Speed means: rate and pitch together, or rate alone.

Reverb and Space. Unaffected directly. Reverb is applied after the speed change in either mode. One subtle difference: with the toggle off, slowing lowers the pitch of what feeds the reverb, so the tail sits lower. With it on, the tail stays at the original pitch, which can make a slowed edit sound brighter than expected.

Bass. With the toggle off, slowing pulls the kick down, which is why slowed edits add bass. With it on, the kick stays where it was, so you need less Bass. +2 to +4 dB is often enough.

Tone. Covered above: a small cut helps hide stretch artifacts. Sped up edits with the toggle on still benefit from a little brightness.

Width. No interaction.

Daycore and the toggle

Daycore is slowed music with little or no reverb, and it is sometimes confused with pitch-preserved slowing. They are different. Daycore keeps the pitch drop; the point is the lower, slower feel without the room. Pitch-preserved slowing keeps the key. If you want daycore, use the daycore maker settings with the toggle off. If you want a practice track, turn the toggle on and leave reverb near zero.

Settings by goal

Mistakes with Preserve pitch

• Leaving it on for a slowed + reverb edit. The result is slower but not deeper. If the edit sounds like a normal song dragged out, this is why.
• Using it below 0.70x and blaming the source. The warble is the time-stretch. Compare with the toggle off.
• Expecting it to pitch-shift. It preserves pitch while changing tempo. It never changes pitch on its own.
• Forgetting it is saved in presets. Custom presets store the toggle state. If a preset sounds wrong on one track, check whether the toggle is on.
• Judging it on the intro. Artifacts show on dense sections and sustained vocals. Test the chorus.
• Expecting the download to match an in-key preview. The toggle does not reach the export. Check the file before you send it to anyone.

Preserve pitch and the export

The exported file is MP3 at 96 kbps, 32 kHz, encoded in a web worker in your browser. The speed, reverb, bass, tone and width you set are all applied to the file. Preserve pitch is not: the export renders at the chosen playback rate with pitch following speed, so a 0.85x download is about 3 semitones lower even if the toggle was on while you listened. This is how the tool currently works, not a bug in your file. The export is fine for YouTube, TikTok and Shorts because those platforms re-encode. For a file that keeps the original key, or for a release master, use a WAV source and Audacity's Change Tempo or a DAW with a dedicated time-stretch algorithm; the editor does not export WAV.