Filter selection can be a deeply personal choice for many artists. Some circumstances call for cleanliness and transparency of a filter while others beg for a little additional color and bite. Some filters are ideal for wild sound design and others are better for a surgical mixing session. Beyond just trying out different objects and listening for what sounds good, it can be helpful to gain understanding of filter design concepts like frequency response types, topologies, and orders and make filtering choices from that knowledge. After all, who doesn’t love being the one at parties who can explain the differences between Butterworth and Chebyshev Type-II filters?
If you’ve wanted to level up your filtering game but didn’t know where to start, look no further!
A place to begin
The Audio Filtering Overview is a good first walk through the native filtering objects in Max. It covers “all-in-one” options like onepole~ and allpass~ and then goes further into more customizable objects like filterdesign and filtercoeff~.
MSP Filter Tutorial 1 : Simple Filters covers what filters are, common filter parameters (like slopes and cutoff frequencies), introductions to the lores~, reson~, and svf~ filter objects. The tutorial also covers the basics of how filtering works for digital signals.
MSP Filter Tutorial 2 : Variable Type Filters goes the next step and looks at the biquad~ and cascade~ objects which pair nicely with filterdesign, filtercoeff~ and filtergraph~.
MSP Delay Tutorial 6: Comb Filter explains how filters are constructed using combinations of very small delays. The comb~ and teeth~ objects are two native MSP comb filters.
If you’re looking for materials on video filtering, check out the filters section of the Jitter Tutorial 50: Procedural Texturing & Modeling.
For the visually-inclined, there are a couple of videos by Tim Place which cover filtering tools available in Max as well as DSP theory of filters.
Filters with BEAP
Did you know BEAP is a built-in package to help you model a Eurorack synthesizer right in Max? Inside of BEAP, there are many hidden goodies just waiting for exploration including a number of filter modules.
- bp.Classroom: two-pole multimode filter with large graphical interface and spectral display
- bp.Comb Filter: a comb filter with a handy dry-wet knob
- bp.Diode Ladder: an emulation of the diode ladder lowpass filter found in the Roland TB-303
- bp.HPF: a highpass filter
- bp.Ladder: an emulation of the 24dB/oct Moog transistor ladder filter
- bp.LFP: a lowpass filter
- bp.MFFB: a 16-band filter with signal-controlled amplitudes
- bp.MMF: a two-pole multi-mode filter with a graphic display
- bp.Spectral Filter: a 256-band FFT-based signal-controllable spectral filter
- bp.Spectral Image Filter: an image-controlled FFT-based filter
- bp.Triple Morphing Filter: three bandpass filters with a single macro control, inspired by the Buchla 291e
- bp.VBWBP: a variable bandwidth, variable slope bandpass/band reject filter
For more on BEAP, check out my colleague Darwin's series of articles and video tutorials.
A call for gen~
When you want to program your own filters, you’re very quickly going to want control over your patch on a sample-by-sample basis. If that doesn’t sound like a job for gen~, then I don’t know what does! If you’re new to gen~, and want to go beyond the examples provided here, check out the documentation for the ultimate resources list. The easiest place to get started with filters in gen~ is to search and open up the gen~.filters.maxpat example patch. There you can find examples of one-pole filters, allpass filters, state-variable filters, resonant bandpass filters, and biquad filters.
Beyond the examples in gen~.filters.maxpat, there are even more patches to explore:
- gen~.comb.maxpat - An implementation of the comb~ object
- gen~.crossover.maxpat - Crossover filter
- gen~.moogladder.maxpat - Moog ladder filter
- gen~.pfft_example.maxpat - gen~-based FFT filter
Max4Live creative filtering
Remember that you can use any Max4Live device in your own Max patches by simply dragging and dropping the device onto your Max window! Try taking a look first at Cycling '74's Pluggo for Live pack available for free from the Ableton website. In there you can find creative effect devices including a number of wild filtering options like FilterTaps, Mangle Filter, Phone Filter, and Harmonic Filter, to name a few.
Even further, with thousands of devices available on maxforlive.com, a search for "filter" will show you countless options for creative filtering in your patches.
When you find a device you love, try opening it up to take a peek into its inner workings. You might just find a new filtering technique to add to your own toolkit.
If you’re looking for more resources on learning about filters because you’re ready to start gen~ patching or are just curious about going deeper into mathematics and DSP, two widely recommended and freely available books are Introduction to Digital Filters with Audio Applications by Julius O. Smith III and The Scientist and Engineer's Guide to Digital Signal Processing by Steven W. Smith, Ph.D. (particularly starting at Chapter 14 for filters).