Absorbers remove energy
An absorber turns sound into a tiny amount of heat inside a porous or resonant structure, so less energy comes back into the room. Absorbers fix too much sound: boom, boxiness, a long reverb tail, flutter. Fresnelcut's slat and perforated-panel absorbers are tuned resonant traps for the low-mid range where boom lives.
Diffusers redistribute energy
A diffuser keeps the energy in the room but spreads each reflection across many directions. Diffusers fix harsh, uneven reflections while keeping the room feeling live and spacious. They do nothing for boom — scattering a bass note doesn't make it quieter.
Which do I need?
- Boomy, boxy, one-note bass → absorber
- Echoey, harsh, ringing highs → diffuser
- Dead and lifeless already → diffuser (don't add more absorption)
- A real room → usually both, in different spots