diffuser-design
QRD Diffuser Cutoff Frequency Explained: The Real Limits
A QRD has no single cutoff. Depth sets the low end, well width sets the c/2w ceiling, and N times the design …
Diffusers Guide — How QRD sound diffusers are sized and placed.
How QRD sound diffusers are sized and placed.
Diffusers Guide
Independent · 2026
Independent · 2026
room-treatment
Diffuser vs Absorber for Room Treatment: Which Goes Where
Diffuser vs absorber for room treatment: absorb bass and first reflections, then diffuse the rear wall only if you sit far enough away from it.
Read the article →Latest Guides
diffuser-design
How Schroeder Diffusers Work: The Math Behind QRD Scattering
Explore how Schroeder diffusers use quadratic residues and reflection phase, what Fourier theory predicts, an…
build-guides
How to Build a QRD Diffuser: Cut List and Depths
A worked cut list for a seven-well quadratic residue diffuser, plus fin seating, mounting distance and the re…
diffuser-design
QRD N7, N11, N13 and N17: Well Depth Tables and Formula
Use the QRD well-depth formula and worked N7, N11, N13 and N17 tables to choose a prime from design frequency…
diffuser-design
Types of Acoustic Diffusers: QRD vs Skyline vs BAD
How one-dimensional wells, two-dimensional block arrays and binary amplitude panels differ in scattering plan…
diffuser-design
Acoustic Diffusers: How They Work vs Absorption
Learn how acoustic diffusers redistribute reflections, how diffusion differs from absorption, and which measu…
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Tool
QRD diffuser sizer
Well depth sequence, deepest well, high-frequency limit and period width for N7 to N17.
Reference
QRD well depth tables
The residue sequences for each prime, and what a fixed depth budget actually buys.
Build
Build a QRD diffuser
Worked cut list for a seven-well panel, plus mounting distance and failure modes.