A mashup puts the acapella of one song over the instrumental of another, with the vocal pitched to the instrumental's key and sped to its tempo. Open the Key finder (also at key.aden.space), drop an instrumental and an acapella, and it fits the acapella to the instrumental, puts its bar 1 on the instrumental's bar 1, and rates the pair as a great, good or hard match. Then you cut, fade and save the mix.

What you need

• An instrumental. The beat, chords and bass the vocal sits on.
• An acapella. A vocal on its own. Official ones, released by the artist or label, sound cleanest.
• Or a whole song you split. Split vocals in the Key finder splits a track into an acapella and an instrumental with AI. It needs an account and is on the Max plan (more below).
• The key and BPM of both. The Key finder reads them for you. See how to find the key of a song.

How do I match the key of two songs?

If the two keys already mix on the Camelot wheel (the same key, the relative key, or one number either side), leave the acapella where it is. If not, pitch it the shortest way to the instrumental's key.

Pitching keeps the mode, so a minor vocal stays minor. Over a major instrumental, a minor acapella aims for the instrumental's relative minor, which shares every note and mixes perfectly.

How far can a vocal move? As a rough guide, a semitone passes as the original, up to three semitones still sit in a mix, and beyond that most voices start to sound processed: thin going up, heavy going down. When the gap is big, pick a target between the two keys so both parts move part of the way.

How do I match the tempo?

Speed the acapella to the instrumental's BPM. The change is the instrumental's BPM divided by the acapella's, minus one: 124 to 128 BPM is 3.2% faster.

Far apart? Try half or double time before you stretch anything.

A few percent is hard to hear, while 8% or more starts to drag or rush a vocal. In the Key finder, key and speed are separate settings per track, so speeding up a vocal does not raise its pitch. Without key lock, about 6% faster also means about a semitone higher. If a BPM looks off, see how to find the BPM of a song.

What do Great, Good and Hard match mean?

With two tracks or more, a chip beside the tempo says whether they make a mashup with the anchor:

The weakest pair speaks for the mix. Open the chip for each track's verdict and what it takes ("Up 2 semitones · 1.4% faster", or half or double time), and press one to fit the wheel to it. A hard match can still work: expect to hear the processing, and keep the overlap short.

Make a mashup in the Key finder, step by step

1. Open the Key finder.
2. Drop the instrumental and one or more acapellas. No files yet? Type each song's name or paste a link. It becomes a lane waiting for its audio, with its key and BPM already read. Drop the file on its lane later; a file whose name holds the song's title ("One More Time (Acapella).wav") fills that song's lane wherever you drop it.
3. Check the anchor. The Key finder guesses the instrumental from its file name and marks it as the anchor: its key becomes the target and its tempo the tempo. To pick another, use Fit the others to this track in a track's … menu. Every other lane says how far it is pitched ("+5 st") and sped ("-0.8%", with ×2 or ×½ when half or double time fits better).
4. Read the match chip beside the tempo.
5. Line up the beats. A new track lands tempo matched with its bar 1 on the anchor's bar 1. To move a clip, drag it by its top strip: its beats snap onto the anchor's, finer the closer you zoom. Hold Alt to place it freely. With the strip focused, ← and → move it a step, Shift a bar, Alt 10 ms. An acapella has no drums to lock to, so check that the vocal starts on the bar you want.
6. Cut and fade. Drag a clip's left or right side to cut it, and drag the knob in either top corner inward to fade it in or out. A double click puts it back.
7. Balance it. Each lane has mute and solo; hover the speaker for its level. Press a track's pitch and speed to pick its key, step it a semitone or type its BPM. Minus and plus beside the play button speed the whole mix up or slow it down a BPM at a time.
8. Press Space to play and pause, and listen to the whole thing through.

In ChatGPT or Claude, add Key finder by Aden (mcp.aden.space/key-finder) to ask how far one key is from another.

Split a song into acapella and instrumental

The layers button on a track (it shows when you point at the track) splits it with AI into an acapella and an instrumental, as two tracks under it: same spot, cuts, fades, level, key and speed. The original goes quiet, so the mix sounds the same until you unmute it or change something. Splitting takes about a minute, needs an account and is on the Max plan.

AI separation is good, not perfect: expect some hi-hat or reverb left in the vocal, and some vocal in the instrumental, most of all on dense mixes. An official acapella is still cleaner.

Save the mashup with its stems

Save to Aden, under the playlist, saves the whole mix as a new track: every lane you hear, where it sits, cut, faded and levelled, in the target key at the mix's tempo, as an MP3 named after its songs ("Byte vs We Found Love"). New track opens with its BPM and key filled in.

• Stems. With two lanes or more, each lane comes along as a stem of the new version, starting where it sits in the mix. Together the stems add up to the mix, so you can solo the acapella or take the parts into a DAW.
• Links to the originals. Once created, the track is linked to the songs in it as a mashup of each: a song found by name, or a track opened from Aden (a dropped file without a song has nothing to link). Linked songs on Aden ask their team to approve.
• No account yet. It all waits in your browser while you sign up, and lands in your new workspace.

Can you release a mashup?

Not without permission. A mashup uses two recordings and two songs that belong to other people: the recordings to their labels or artists, the songs to their writers and publishers. Releasing it on streaming services or selling it needs a licence from each of them, and distributors generally won't take a mashup without one. Posting it as a free edit doesn't change that, and platforms can take it down or claim it. The approval Aden asks for when it links your mashup to a song on Aden is about that link, not a licence to release. For who owns what, see master rights vs publishing rights. This is not legal advice.

FAQ

What do I need to make a mashup?

An acapella of one song, an instrumental of another, and the key and tempo of each. The free Key finder reads both, fits the acapella to the instrumental, and lets you cut, fade and save the mix.

How many semitones can you pitch a vocal?

As a rough guide, one semitone passes unnoticed and up to three still sit in a mix. Beyond that most voices start to sound processed, so look for a closer pair or move both parts part of the way.

What if the two songs have very different tempos?

Try half or double time first: an acapella at 87 BPM fits a 174 BPM instrumental in double time without changing speed. When you do stretch, a few percent is hard to hear and 8% or more starts to show.

Is it legal to make a mashup?

Copyright applies to both recordings and both songs. Releasing a mashup on streaming services or selling it needs permission from their owners. Without it, distributors generally refuse it and platforms can take it down.

Can I make a mashup without an account?

Yes. Reading keys, fitting, lining up, cutting and fading need no account, and your files stay in your browser. Split vocals needs an account on the Max plan, and Save to Aden keeps the mix waiting while you sign up.