Vocal Remover (Karaoke / Instrumental Maker)

In most pop and rock mixes the lead vocal is panned dead centre, so it is identical in the left and right channels. Subtracting one channel from the other cancels it, which is the classic way to make a karaoke or instrumental track. This tool does that inside your browser, can keep the bass and kick (also centred) and lets you set the strength. It does not pull instruments apart one by one the way dedicated separation software tries to, so results depend on how the song was mixed.

How to use this tool

1. Choose one or more stereo songs.
2. Leave strength at 100% and "Keep bass" at 150 Hz to start with.
3. Press Calculate and listen. If the vocal is still clear, the mix has it off-centre or with heavy stereo effects; if the drums vanished, try keeping cymbals.
4. Download the instrumental as MP3 or WAV.

Formula

centre M = (L + R) ÷ 2 · out L = L − s × (M − low(M) − high(M)) · out R = R − s × (M − low(M) − high(M))

s is the strength (0–1). low(M) is the centre below the bass cut-off and high(M) the centre above 8 kHz (4th-order Linkwitz-Riley filters, only when those options are on); they are added back so bass and cymbals stay, while in the voice range they are practically zero and the centre cancels. At full strength with no filters, out L = (L − R) ÷ 2 and out R = (R − L) ÷ 2: the two sides are in opposite phase, which is why the "Mono" output (out L on its own) is offered for single speakers.

Example

Take a mix with the singer at 600 Hz in the centre, a bass line at 80 Hz in the centre and two guitars hard left and right. At 100% with "Keep bass below 150 Hz", the singer drops by about 48 dB (the filter that keeps the bass lets through 1/250 of a tone two octaves above its cut-off), the bass stays within 1 dB of its original level, and each guitar is left at half its level in its own channel plus an inverted copy on the other side. A singer whose voice reaches down near 150 Hz keeps more of those low notes.