Reverb Algorithms and Convolution

How room, hall, plate and spring reverbs differ, and where convolution fits among them.

Related

ReverbBusOrgan

The question

Add some reverb cannot be executed. Room, hall, plate, spring and convolution differ in early reflections and density, and the wrong type cannot be rescued by fine settings.

How it works

Algorithmic reverbs build density from delay lines and feedback, with all-pass filters spreading the sound. A room has close, clear early reflections; a hall has longer delays and a longer low end; a plate is dense and bright; a spring carries a metallic dispersion. Convolution calls an impulse response of a real space, credible but less adjustable.

Settings and what you hear

Decay sets tail length, while size suggests volume. Damping lets highs die first and darkens the tail; low diffusion exposes individual reflections, like a hand clap. A two to four second hall suits backgrounds, a one to two second plate suits a snare, and a spring around one second adds audible pitch.

What to listen for

Clap once and compare a room with a hall. Swap a plate onto a snare and hear density change, not only length. Put a spring on guitar and the tail turns metallic.

Common misconceptions

That longer decay means a bigger space; that reverb hides tuning problems; that convolution is always more real than an algorithm.

Sources

• Välimäki, Parker and Savioja, Fifty Years of Artificial Reverberation, IEEE TASLP 2012 — background checked, not quoted
• Udo Zölzer, DAFX — Digital Audio Effects, reverberation chapter — background checked, not quoted

Used for fact-checking only; all prose is original.