It is important to note the difference between an official studio acapella and a DIY isolation.
Look for the version labeled "Studio Stem" or "Rock Band Extract." The giveaway of a high-quality version is the presence of the dry vocal during the intro before Swizz Beatz says "Uh huh." If you hear the bassline humming faintly in the background, it is a fake. jay z on to the next one acapella