Boss VF-1 Effect Processor

hey there,
i just got a vf-1 and i'm using it live on stage as a guitar processor.  i have a big problem with feedback.  i'm getting really high end feedback and it's really ugly sounding, not like normal guitar feedback.  i've changed different pieces of my setup just to make sure of the problem, and it seems to be the processor.  anyone had any similar experience?  anyone got any suggestions?
thanx,
dpowell


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