MoFaux vibe a bit too bright

[polifemo]

Hi,

I've got a Sweet Sound MoFaux-vibe that does a pretty descent job of mimicking a "real vibe".

If possible I'd like to take some high end out of the "peaks of the sweep" as those are a bit too bright.
I've adjusted the internal trimmer, but that one seems to control more the depth of the sweeps, making it a bit more "shallow".

Is there a way to clip these high end peaks?