Gotta remember, that the sampling laws that exist now, didn't exist back in the late 80's...sampling laws in any form didn't really come about until the early 90's.
By the time RZA and Pete Rock were doing their brand of sampling, you could use about 3 seconds of sampled audio without paying for it (someone correct me if i'm wrong). That's why RZA sped up his samples...so he could take more of the song.
Even more detailed sampling laws came about at the end of the 90's, and in the mid 2000's.
But as for right now, ANY sample you use in a song (even a millisecond) has to be cleared. Now how much that is enforced is debatable...but that's what the law says.
People try to make hit records to make money, regardless of if it's sampled or not. But when you have a sample in a song, that song/project already starts out in a hole, as you had to pay for the sample, in addition to the other costs in making the song. You also probably had to give up some ownership rights (copyright) in the song as well...so the song is gonna make less money than the equivalent song without the sample.
But a hit is a hit. And you can't place a number (well you can

) on the value a hit brings a career.
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I'm not altering the sample much. I'm using about 12 bars of the song, and looping it, and adding in other elements so that the song does what I need it to do.
I'll tell everyone what the sample is when the record is done and out there. I can't afford for someone to take the idea and run with it before I get it copyrighted, since at the moment it's an uncleared sample.
I'm not even ustreaming the making of the song.
G14 classified kinda stuff.