I get you. You need to mute all the notes before the final loud ringing note. Mute them well using either your fretting hand OR palm (the fleshy part) of picking hand.
I've been learning Serrana for the past 3 months and i'm only on the 10th arpeggio. The only problems I have is with the first 2 sweeps. The way I play it, it really sounds muddy. ;x