I have a lisp on my recordings and do not have one when I talk. Is it cheap Mic's? Or could it be not properly mixed. I use a BR-8, whihc I'm sure is not the problem.
Are these actual lisps (such as a speech impediment that only surfaces when you sing) or is it harsh sibilant tones ("s" sounds, and fricatives like "ch")?
If the problem is sibilance, use a de-esser (band compression/limiting at around 5K). EQ around 5K will help a bit, but not as much as band limiting.