If you like bass, you need a:

Sub-Bass Quadratic Ramp Diffuser

What is it?

A diffuser is a device used to disperse sound reflections to improve a room’s acoustic qualities. Sound that hits a diffuser is not returned as a single echo. Instead, it is radiated in multiple directions over different time intervals, which helps reduce resonances and colouration.

A quadratic diffuser has a surface with varying depths that alters the phase of the reflected waves, causing interference that reduces and disperses sonic energy.

Why Do I Need One?

If you produce music, one of the most important things to consider is your studio’s acoustics. Sound reflections affect the levels of certain frequencies, making some louder and others quieter than they really are. “Slapback” echoes also reduce playback accuracy, making it harder to achieve the results you’re after.

Acoustics can be managed by either absorbing, or diffusing unwanted sound and professional studios tend to use a mixture of both methods. Too much absorption makes a room feel “dead”, muffles speech and reduces stereo imaging. Acoustic diffusion scatters sound around the room, preserving spaciousness, breaking up harsh echoes and reducing room modes (frequency spikes in parts of a room, caused by overlapping, standing waves). Room modes can cause bass notes to sound overly boomy or disappear entirely).

  • Break up reflections

  • Reduce flutter + slapback

  • Avoid deadening the room

  • Reduce low energy buildup

How Do I Make One?

Low-end problems are some of the hardest to fix in any room, and ours was no exception — measurements revealed clear frequency build-ups in the rear ceiling corner, a classic spot for room modes to gather and muddy the bass. Rather than buy an off-the-shelf solution, we decided to design and build our own quadratic residue diffuser (QRD) for that exact corner.

The design followed the maths closely. A QRD works by creating reflective wells of carefully calculated depths, based on quadratic residue sequences, so that reflected sound is scattered evenly across time and angle rather than bouncing straight back. We kept the well bottoms flat — true to the QRD principle — since any curvature would smear the phase relationships the design depends on.

For our space, we built the diffuser as a ramp at a 20° angle with 50 cm deep wells, working out the geometry with simple trigonometry to get a horizontal run of roughly 1.37 metres — long enough to do its job, short enough to fit our 3.6 m room without dominating it. A small air gap behind the panel, lined with rockwool, adds extra absorption in the low-mids where the diffuser itself can't help.

The result is a corner that no longer fights us — reflections are scattered rather than slamming straight back at the listening position, and low-end decisions made in this room now hold up when they're played back on a proper club rig.

Given your room:

2.7 m wide

2.4 m high

3.6 m long

Diffuser at the rear wall / ceiling corner

Speakers + sub at the opposite end (front wall)