SchroederReverb

A lightweight cross-platform VST3 reverb plugin written in C++ with the JUCE framework

My motivation

I'm rather new to digital audio, but as a tinkerer, my first thought when working with audio plugins was: "How can I make this myself?" After some research I decided that Reverb seemed easy enough to replicate. This way I was able to learn digital signal processing, get to know the JUCE framework and the CMake build system and improve my ability to write code in C++ by implementing a real-world application.

Implementation

The Schroeder reverberator works by first feeding the signal into four parallel comb filters. After that the result is sent through two all-pass filters in a row.

Comb filters function by mixing a signal with a delayed version of itself. The implementation is based on the formula:

$FBCF_N^g = \frac{1}{1-g\,z^{-N}}$

The all-pass filter keeps all frequencies at the same amplitude, but changes the phase relationship between different frequencies. I implemented it based on this formula:

$AP_N^g = \frac{-g + z^{-N}}{1 - g z^{-N}}$

I also added UI knobs in order to change Dry/Wet mix, Pre-Delay and Decay easily. The Decay was implemented by adjusting the gain used in the all-pass filters accordingly.

Dependencies

CMake
pkg-config
JUCE dependencies (on linux)

How to build this

git clone --recurse-submodules https://github.com/dkaisr/SchroederReverb.git
cd SchroederReverb
cmake -S . -B build
cmake --build build