Diffusers vs Absorbers: Which to Use Where

By James Hartley · October 10, 2026

The Fundamental Difference

Absorbers remove sound energy by converting it to heat. Diffusers scatter energy in multiple directions, preserving room acoustics while reducing problematic reflections.

When to Use Absorbers

First reflection points: Side walls, ceiling above mix position
Bass traps: Room corners where low-frequency energy accumulates
Flutter echo zones: Between parallel hard surfaces

When to Use Diffusers

Rear wall: Behind the listener
Ceiling clouds: Overhead diffusion preserves space
Live rooms: Recording spaces benefit from diffuse reflections

Types of Diffusers

QRD (Quadratic Residue)

Uses wells of varying depths. Even scattering across a designed range. Most common in studios.

MLS (Maximum Length Sequence)

Binary sequence of fins and gaps. More compact but narrower bandwidth.

Polycylindrical

Curved surfaces with predictable scattering. Simple to build.

The Balanced Approach

Most rooms need both. Start with 25-30% absorption, 20-25% diffusion, 45-55% reflective. Adjust based on measurement.