Buried inside the legendary ReaPlugs bundle, ReaFIR is one of the most underestimated free processors in audio.
Built as an FFT-based dynamics processor, it goes far beyond conventional EQ or compression. From linear phase mastering moves to surgical resonance removal and even real-time noise reduction, ReaFIR delivers serious processing depth with almost no CPU footprint.
For engineers who like precision tools over flashy interfaces, this is a quiet weapon.
Unlike traditional EQs and compressors that operate in the time domain, ReaFIR works in the frequency domain using FFT (Fast Fourier Transform) processing. This allows it to analyze and manipulate audio across extremely detailed frequency bands, with selectable FFT sizes ranging from 128 to 32768.
In EQ mode, ReaFIR can function as a linear phase mastering EQ, making it ideal for transparent tonal shaping on buses and full mixes. Alternatively, you can draw hyper-precise correction curves freehand for surgical resonance removal.
The in/out frequency response display provides immediate visual feedback, helping you see exactly what is being altered.
Because response curves can be drawn using unlimited points or sketched freely with the mouse, ReaFIR offers a level of precision rarely found in free tools.
ReaFIR isn’t just an EQ. It includes multiple operating modes that dramatically expand its utility:
In Compressor mode, each frequency band can be compressed with a fixed ratio and individual threshold behavior, essentially turning the plugin into a customizable multiband compressor without traditional crossover limitations.
In Gate mode, per-band threshold gating allows for frequency-selective cleanup. This is particularly useful for tightening low-end rumble or isolating problematic frequency regions without affecting the full signal.
The most famous mode, however, is Subtract. Here, ReaFIR can learn a noise profile and subtract it from the signal in real time. It’s one of the most effective free spectral noise reduction tools available, capable of removing hiss, hum, and environmental noise when used carefully.
All of this is wrapped in a lightweight, highly configurable interface that prioritizes function over aesthetics.
Why ReaFIR Is Still Essential.
A parametric EQ operates with fixed filter shapes in the time domain. ReaFIR works in the frequency domain using FFT processing, allowing extremely detailed and flexible frequency manipulation, including custom-drawn curves.
In EQ mode, yes. Because it operates in the frequency domain, ReaFIR can perform linear phase adjustments, making it suitable for mastering tasks where phase coherence is critical.
For many tasks, yes. Its per-band threshold compression allows frequency-specific dynamic control without fixed crossover bands, offering more granular control than many traditional multiband compressors.
When used properly, it’s highly effective. By capturing a noise profile and subtracting it, ReaFIR can remove steady-state noise such as hiss or hum. However, aggressive settings can introduce artifacts, so careful adjustment is essential.
Higher FFT sizes improve frequency resolution but increase latency and CPU use. Smaller FFT sizes respond faster but with less precision. The correct setting depends on whether you prioritize detail or responsiveness.
