Most of the tracks come from old vinyls, or CD's, that are made of not remastered vinyls.
Most of the recordings sound dull (if that's the right word for it, I'm not native English), like you'd place a cardboard box over your speakers.
One of the worst examples I can show is this:
http://www.youtube.com/watch?v=LFkw6mpRRPQ (not uploaded by me, but someone used the same 'source')
I also got vinyls with a crack on it I never play, but it would be great to record them on the Mac and remove the crack so I can listen to them again.