Exercise 5

Exercise 5: Audio Filters and Delays

Learn how to construct a few common filters, and design your own delay effect from scratch.


We’re learning how to...

  • create in Max a resonant lowpass filter,
  • design a basic delay effect with feedback and smoothly changing delay time,
  • create a stereo delay effect by providing a separate delay line for each channel, and
  • feed the filtered signal into the two delays, and make a few presets that capture parameters you like.

How to Do This Exercise

Working on the assignment is a three-stage process: studying the tutorial patches, watching some short instructional videos, and making a patch that sends a filtered sound into a stereo delay effect.

  1. Download Exercise 5 Max Tips. This folder of Max patches shows you how to use two common filter objects and implement a delay effect with feedback.
  2. Watch the following videos, in the order listed. You could go through the tutorial patches carefully instead, but the videos will probably get you closer to understanding a solution for this assignment. Use whatever method works for you: tutorial patches or videos.
    1. A Max Audio Filter
    2. Basic Delay Concepts
    3. Building a Simple Delay Effect in Max
    4. Adding Feedback to Your Delay
    5. Making a Stereo Delay
  3. Make a patch that creates a delay effect with feedback. Use a sound file player to test it. Then create a resonant low-pass filter using biquad~, controlled by filtergraph~, and patch the filter between the sound file player and the delay effect. Finally, duplicate your delay effect, so as to create a stereo delay effect, with different delay times for the two channels. Save some delay parameters in presets.

    To summarize, your patch should have

    • a sound file player, which feeds
    • a resonant low-pass filter, which feeds
    • two delay effects in parallel, which connect to
    • the two channels of a live.gain~ and ezdac~.

    It would also be nice to have the ability to adjust the wet/dry mix for the delays. You could add another live.gain~ for the signal coming directly out of the filter — this would be the dry signal — and connect both faders to the ezdac~.

    Later we will learn how to use a crossfader to implement a more convenient wet/dry mix control. The last video above demonstrates another solution.

Be sure you understand what each of these Max objects does:

  • onepole~
  • biquad~, filtergraph~
  • tapin~, tapout~


  • Be sure you satisfied the criteria listed above.
  • Submit your Max patch in Canvas.

Grading Criteria

This exercise is graded pass/fail. You must submit the exercise by Thursday midnight to be eligible for a pass.

Your patch must

  • operate correctly and
  • implement the functionality described in the “How To Do This Exercise” section above.