The Yamaha AN1x Synthesizer mailing list

The AN1X filter can be modulated by LFO 1. Go to the LFO section, 
change LFO to a square wave and set the speed to taste. Then go to the 
filter section and set the amount you want the filter modulated. Try 
negative amounts as well as positive amounts. 

Or set the ribbon controller X value to filter and tap the ribbon 
controller. Tapping the ribbon will give you the staccato filter change 
like a square wave but it's easier to get the filter synched up to 
tempo. 

Rainbow Jimmy