of Audio Unit effects.
Requires OS X 10.6 or higher.
How to customize the parameter display colors
There's a level meter tied to the touch wah sensitivity to help you adjust OttoPhilter to suit your playing dynamics. OttoPhilter has two driven resonant filter sections that are applied to each stream. The input stream is split in two and feed into the two filters. The second stream can be set to provide a suboctave. This gives a wide range of touch/auto/filter sweep effects. Download it and have some fun.