If you can't get hold of the acapella from the track you want to remix, you might just be able to nab it out of the full mix. The technique involved might look like magic but it's actually just the physics of sound doing its thing - let's check it out…
Step 1: When two identical signals are played in sync, phase reinforcement occurs, resulting in a 3dB boost in overall gain. If you invert the polarity of one channel, the sound will disappear, as the two signals will be out of phase with each other. This is known as phase cancellation, and we can use it to easily extract the vocal from a full mix in any DAW.
Step 2: Start by setting the tempo to 135bpm and importing Instrumental.wav and Vocal Mix.wav onto separate channels (click here to download the files). Line up the two mixes so that they start at the same point, then use your DAW’s utility plugin to invert the polarity of the instrumental. You’ll hear the backing track disappear like magic, leaving just the vocal intact.
Step 3: While this technique is great for extracting vocals, we can use it to isolate other sounds, too. This instrumental mix has a 16-bar drum section at the end, which we can use to cancel out the drums from the full mix. Move the vocal mix forwards by 16 bars and you’ll hear the main break disappear, leaving just the music and a quiet drum reverb.