DIY project QRD 17 (plans from Acoustic Fields)

About the DIY project QRD 17 (plans from Acoustic Fields)

The DIY project QRD 17 is a Quadratic Residue Diffuser (QRD) based on the prime number 17 sequence. It is designed to diffuse sound energy starting at approximately 225 Hz and extending up to 3,450 Hz, improving room acoustics by breaking down strong reflections into smaller, less recognizable reflections. The diffuser consists of a series of wells of varying depths calculated using quadratic residue sequences, with a constant well width typically around 2 inches. The diffuser is constructed using cabinet grade or marine AA grade plywood, with 12mm thickness for the back, top, bottom, and sides, and 6mm plywood for the fins separating the wells. Assembly involves gluing and screwing the pieces together, with spacers used to achieve the correct well depths. The diffuser can be mounted vertically or horizontally and is suitable for professional and home studio acoustic treatment to create a more diffuse sound field and enhance spatial clarity.