I've put together a πano here:
It's based closely on http://pipad.org/src/spiral/Jaffe-Smith-Extensions-CMJ-1983.pdf -- in fact the variables and expressions in my filters.h file match the equations in the paper, although I've tidied up the maths in a couple of places.
It performs perfectly well on my 3.1GHz iMac, if anyone would care to test drive it on a mobile device I would be interested to know whether it hacks it.
Critique / feedback / even code contributions & collaboration most welcome as always. I know my AudioSettings.h is a bit of a mess, I lifted it from another project.
I'm not deriving from AudioAppComponent as (1) I like to do it manually as an exercise, (2) I want to keep the possibility open for handling microphone input separately.
Also I'm not sure what the best strategy is for putting a JUCE project up on GitHub ... I'm including the whole of JUCE, which is rather inelegant. Also Visual Studio project gubbins. Ideally I think I would just have my own source files, the ProJucer file, and maybe some cunning way of forcing the JUCE files to download... would be quite nice if the ProJucer could remember the location of them independent of the project, even keep them updated...
If anyone is interested in using it, I can help out on IRC...
PS I could optimise my filter code some, but I don't think I can process it entirely in blocks as it involves a feedback loop.