Heres Sum Tips For The People That Want Acapellas That Havent Been Released And Can Do Yourself
heres an overview of the different methods used for extracting vocals...
1. THE PHASE CANCELLATION METHOD
Get an instrumental of a song, invert the phase (sometimes refered to as flipping), and mix it with the original.. If done right everything besides the vocal is cancelled out. You can do this in any sequencer like cubase or acid.. The instrumental must be excatly the same time/pitch however. and mp3s might not work if they are badly encoded. Zoom right in to see the 2 waveforms next to each other (look for kick drum hits) and line them up.