recording mp3

Hello, i ve been using audacity to record songs that i have on my hard drives,from my dj kj days. many many of my recording come from the mp3 section of a karaoke cdg, mostly sound choice, which comes very close to the original recording. here is my problem. many songs that i want to record, were never made into cdg (karaoke). of course i have all these songs as normal mp3 recordings, but i need to record them in audacity, without vocals. i have tried to remove vocals under the effects tab, without , but failed. so how do i take a normal mp3 recording and remove all vocals??? thank you

“remove vocals” only works on certain songs : those with center-panned vocal with no reverb effect , (or other stereo effects).