You should mess with a comb filter. It's really fun to use for basses imo. The way I use it though is to smoothen out the rough edges on the distorted waveform (when put through so many effects). That's if you turn the decay down. I really would like to see what you can do with it. Another thing I also do with the comb filter is automate the tune (yellow knobs) weirdly and randomly to get some cool stuff. And since a comb is a filter, it technically can help you with vowels.