Hello,
Where do you get your samples from? Youtube or from records?
Your source is the most important part, because it determines the quality.
I only take my samples from records because the quality is good,
If you take samples from Youtube and download them with a youtube downloader you get a bad quality sample all of the times because when someone uploads music to youtube it gets compressed and some quality gets lost, when you download it as a .mp3 it get compressed again.
so their isn't really a way clear up the sample because the quality is bad, your only choice is to find the song on another video or other source, or what I would do is find the sample on a record.
Good Luck