Peter Johnson discusses the effective use of a quadratic diffuser as it relates to recording or mixing sound and instructs on how to make an effective, sturdy and inexpensive piece of acoustic equipment, ready to mount. Written directions, the wood piece length chart and grid pattern referred to in the video can be found in Audio Engineering 101 by Tim Dittmar or on Audio Undone: Do-it-Yourself Acoustical Treatments: How to Build a Diffuser.