i'm mixing a thrash band, guitars have a nice tone, but they don't have that sharpness i'm looking for, they're too soft and mellow. Any ideas? tips about compression?
Compression just controls dynamics, and thus has little use on distorted guitars, and practically zero effect on sharpness; for that you'll want eq, but more importantly, you'll also wanna post clips
Soft and mellow is a good start. Easier to deal with than high fizzy noise which you have to search for to . First try an EQ with a high shelf from 3000+ hz or so, just a little will make the tone brighter without changing much of the character itself.
Maybe you could play around with the 1-8 kHz area . 4 kHz might be where the sharpness is ?! depends on what you mean by sharpness ...I think you mean where the gain really "bites" on palm muting ?! edgy but not too fizzy.