Why does the pitch change with the speed?

Because the edit is a resample, the same thing that happens when a tape machine runs at the wrong speed. Playing the samples faster makes the music faster and raises its pitch by the same proportion, which is what gives both these edits their character.

Why does nightcore not use the reverb?

Because the effect it imitates is dry. A nightcore edit is about brightness, tempo and a higher pitch, and adding a wet tail would work against that by blurring the transients that the speed increase has sharpened.

Why does the output run past the music?

Because the reverb tail keeps ringing after the source has finished, and cutting it off at the music's end would produce an abrupt stop. Some listeners trim the tail afterwards, which is fine; leaving it in is the more natural result.

Can I slow the track without changing its key?

Not here, since the edit is defined by the pitch moving with the tempo. Slowing at the same pitch requires time stretching instead, which is what the tempo changer does, and the result will sound smoother but will lose the tape character that makes these styles recognisable.

Slowed + Reverb / Nightcore

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Slowed + Reverb, Nightcore produces the two classic edits in one place: a slowed copy that drops in pitch with a reverb behind it, or a nightcore lift that takes the tempo and pitch up together.

What is Slowed + Reverb / Nightcore?

Choose a style, set the speed, and create the edit. Both are remixes in the tape tradition, a slowdown and a speed up, each of which takes the pitch of the music with it; in the slowed style a reverb is added to the result, and in the nightcore style the sped-up copy is left dry.

The styles and the controls:

Slowed, with a speed from sixty to a hundred percent of the original, defaulting to eighty five, and a reverb mix from nothing to sixty percent, defaulting to thirty five.
Nightcore, with a speed from a hundred and five to a hundred and fifty percent, and no reverb.
A report giving the speed as a percentage, the equivalent pitch movement in cents, either the reverb mix and its tail length or simply that the result is dry, and the output duration.

Both styles are built on one piece of arithmetic that is worth understanding, because it is the reason these edits sound the way they do. The speed change is a resample, the same operation a tape machine performs when it runs at the wrong speed: playing the sample data faster or slower makes the music move faster or slower and moves its pitch in exactly the same proportion. That is why a slowed copy sounds lower as well as slower and a nightcore copy sounds higher as well as faster, and it is the opposite of the time stretching that a tempo changer does, where pitch and duration are separated. The report states the pitch side directly in cents, which for the default slowed setting of eighty five percent works out at about two hundred and eighty cents down. Two hundred and eighty cents is a little under three semitones, which is why a slowed track so often ends up in a different key from the original. The slowed style then adds a reverb with a fixed character: a small room of a little over a second, a long feedback and damping that removes the top end of the tail, mixed at the level you set, with a two-second tail that rings past the end of the music. That tail is the reason the style is named for the reverb as much as for the speed, since it is what turns a slowed loop into something that sounds like a live recording. The nightcore style skips the reverb because the effect it imitates does too: the point there is brightness and energy rather than space.

Where it is limited:

The speed change moves the pitch with it, so the key changes as well as the tempo.
One reverb character, with only its level adjustable.
Two fixed speed ranges, one below and one above the original.
The reverb tail extends the file beyond the music rather than being trimmed to its length.
No separate control of pitch and duration.
Output is sixteen bit WAV.

Use it when the edit itself is the goal: the slowed, reverb-backed version that has become a genre of its own, or the brighter faster lift of nightcore. When the tempo should change without the pitch moving, the tempo changer separates the two, and when only the pitch should move, the pitch shifter and the pitch shift calculator are the tools for that. When a different reverb character is wanted, the convolution reverb and the reverb simulator offer more control than the fixed tail here.

How to use Slowed + Reverb / Nightcore

Drop an audio file onto the panel and let it decode.
Choose the slowed style or the nightcore one, which determines the available speed range.
Set the speed, and in the slowed style the reverb mix as well.
Create the edit, then check the reported cents figure if the key change matters.

When to use Slowed + Reverb / Nightcore vs related tools

Slowed + Reverb, Nightcore is the tool for the two named edits, pitch and tempo moving together as they do on tape. Tempo Changer changes the speed without moving the pitch, and Audio Pitch Shifter moves the pitch without changing the duration. When the reverb should be chosen rather than fixed, Convolution Reverb and Reverb Simulator give the controls this edit deliberately does not.

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