Oliver's Audio Passion - 2D QRD N23 diffuser made by Branislav G. from Slovakia, using my Diffuser Calculator app 😎 🛒 Application ---> https://play.google.com/store/apps/details?id=acoustic.oliver.diffusers&hl=en_US | Facebook
Calculate a Two-Dimensional Primitive Root Diffuser
Online Acoustic Calculators [English version] - Рекомендації по акустиці приміщень - Aкустические материалы и Технологии