On and off
The switch at the top of the panel turns the effect on and off in the tab you're in. When it's off, the song plays exactly as it normally would. Each tab has its own setting, so one tab can be slowed while another plays normally. The first time you click the icon on a song, it turns on Slowed + Reverb for you.
Presets
Slowed + Reverb plays the song at 80% speed with some reverb. Nightcore plays it faster, at 120%, with no reverb. Picking a preset replaces whatever you had and turns the effect on. The line above the tabs shows which preset is playing, or says Custom once you've changed something.
Speed
Slows the song down or speeds it up. Like a record played at the wrong speed, the voice and instruments get lower as the song slows down, and that drop in pitch is a big part of the slowed sound. If you'd rather keep the original pitch, see Keep Original Pitch below. Speed doesn't work on YouTube live streams, but the other effects do.
From 0.50× to 1.50×, in steps of 0.05.
Reverb
Makes the song sound like it's playing in a big room. A little adds some space around the voice, and more gives you the washed-out sound. As you add reverb, the original sound is turned down slightly so the overall volume stays about the same.
From 0 to 100%. The reverb fades out over about two seconds.
Low, Mid and High
These are bass, middle and treble. Drag a dot up to make that part of the sound louder or down to make it quieter. Raising Low is a quick way to make the song sound heavier. You can also click a dot and use the arrow keys.
Each goes from −12 to +12 dB. Low is around 200 Hz, Mid around 1 kHz and High around 4 kHz.
Reset Defaults
Puts every slider on Basic and Advanced back where it started and turns the effect off.
Keep Original Pitch
Changes the speed without making the song lower or higher. When the song is slowed down this can sound a bit robotic, and the panel shows a warning about that. Leave it off if you want the classic slowed sound.
Echo
Repeats what you hear, with each repeat a little quieter than the one before. Reverb blurs the sound, while echo gives you separate repeats you can pick out.
From 0 to 100%. The repeats come every 0.35 seconds.
Pan
Moves the sound toward your left or right ear. It's in the middle to start with.
Width
Makes the sound feel narrower or wider, which is easiest to hear in headphones. At 0% both ears get the same sound. 100% is the song as it was recorded, and above that the sound spreads out wider.
From 0 to 200%.
Saturation
Adds a bit of distortion. A small amount can make the song sound fuller. A lot, especially with Low or High turned up, sounds harsh.
From 0 to 100%.
Built-in limiter
There's no slider for this one. It stops loud combinations of settings from distorting, and you don't need to do anything with it.
My Presets
To keep a sound you like, type a name under My Presets and press Save Current. Click a saved preset's name to use it again. The pencil lets you rename it or change its sliders. The tick saves those changes and the arrow cancels them. The × deletes the preset. Your presets are kept in your browser and aren't sent anywhere.
Colors
The palette icon switches the panel between four color themes: Terminal, Midnight, Paper and Frost. The theme is the same in every tab. On this site it changes the page colors too.
Keyboard shortcuts
You can turn the effect on and off from the keyboard. There are three shortcuts, and none of them has a key until you choose one:
- Toggle Slowed + Reverb preset turns on Slowed + Reverb, or turns the effect off if Slowed + Reverb is already playing.
- Toggle Nightcore preset does the same with Nightcore.
- Toggle last preset turns the effect off if it's on. If it's off, it turns it back on with the tab's last settings, or with Slowed + Reverb if there aren't any.
To choose keys in Chrome, type chrome://extensions/shortcuts in the address bar (in Edge it's edge://extensions/shortcuts). In Firefox, open Add-ons and Themes from the menu, click the gear icon and choose Manage Extension Shortcuts.