The Myriad Types of IIR Filters
Ah yes, the humble one-pole filter. Workhorse of DSP. What's this now? Biquads! But what about SVF? And what is TPT? And how do I de-cramp these things, massage or a hot towel? Speaking of which, what is damping... What if I don't want to do a whole bunch of math and just need to know practical implications? When do I use what kind of filter? What's state of the art? Is it even useful? My lord I forgot entirely about crossovers, but I have a vague recollection of something about stacked Butterworths, and now I'm hungry for pancakes. What are these X's and O's in the circle on this graph!? Please make it make sense.
Okay, I'll bite. Sit down and kick back for an organized survey of the myriad types of linear IIR filters out there from a practical perspective: a bit of technicality followed by an awful lot of practical tips, explanations, applications, and other deep thoughts about how to put other peoples' beautiful math to work.
Samuel Fischmann
CEO
Musik Hack LLC
Sam is the CEO and co-founder of Musik Hack, and a seasoned software developer whose portfolio spans audio/DSP, Web development, data analytics, and embedded systems. He’s also a composer and longtime musician. Sam is obsessed with building creative, functional, major-label-quality products, and helping spread the joy of music through more intuitive approaches to DSP. If you ask nicely, he can also cook up a mean marinara...