Quote Originally Posted by darkjuice View Post
I've known quite a few artists to speed up/ slow down their instrumentals a fraction of a second so that the inversion technique will not work. I do it when I release instrumental and vocal version as well.
I have done this too when bouncing out audio tracks for artists that didn't want their vocals used in a manner other than intended for. I've used Pro Tools to engineer acapellas from an inverted instrumental. Some programs have a vocal remover feature, and that can work depending on how the source file was mixed. It just does the same inversion trick but to the left channel and mixes it over the right channel or vise-versa. I have made a few Eminem acapellas from this technique. It does help to zoom in as close to each peak and valley to align it up. Good luck with your acapella making. :)