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Resonance suppressor vs dynamic EQ

A dynamic EQ and a resonance suppressor can both tame problem frequencies — but they work differently and shine in different situations. Here is how to choose, and how to get a free one.

By Reinhardt BuhrUpdated June 20266 min read
Quell's spectral display showing automatic resonance suppression across the spectrum
A resonance suppressor finds peaks automatically; a dynamic EQ waits at fixed bands.
Short answer

A dynamic EQ reacts at fixed bands you choose; a resonance suppressor automatically finds and ducks resonant peaks across the whole spectrum as they pop up. Use dynamic EQ for known, specific problems; use a resonance suppressor for fast, broadband smoothing of harshness and ringing. Quell does the latter, free.

How a dynamic EQ works

A dynamic EQ is an equaliser whose bands only act when the signal crosses a threshold. You place a band at a specific frequency, set a threshold, and it cuts (or boosts) only when there's enough energy there. It is precise and surgical: you decide exactly where and how much. The catch is that you have to find every problem frequency and set up a band for each one.

How a resonance suppressor works

A resonance suppressor analyses the whole spectrum continuously and automatically identifies frequencies that ring out or jump above their neighbours — the definition of a resonance. It then ducks just those peaks, just when they occur, across dozens of micro-bands at once. You don't tell it where to look; it finds the resonances for you and smooths them dynamically.

The key difference

Dynamic EQ
Fixed bands you place manually. You find the problem; it controls it precisely.
Resonance suppressor
Automatic, full-spectrum detection. It finds the problems and tames them for you.
Best for (dyn EQ)
Known, specific issues — a ringing 3.2 kHz, a boomy 120 Hz, a harsh cymbal band.
Best for (suppressor)
Broadband harshness, boxiness and ringing that move around — vocals, drums, busy busses, mastering.

When to use which

Reach for a dynamic EQ when you can clearly hear and locate a single recurring problem and want total manual control. Reach for a resonance suppressor when the harshness is spread out or constantly shifting, or when you just want to smooth a source quickly without hunting for every frequency. In practice, most people use a suppressor for fast cleanup and a dynamic EQ for the one or two stubborn spots that remain.

They work brilliantly together

These aren't rivals. A common pro workflow: let a resonance suppressor like Quell smooth the overall harshness and ringing, then add a dynamic EQ band for any specific frequency that's still poking through. If you came here from the Soothe debate, see the best free Soothe2 alternative and free dynamic resonance suppression explained.

Try Quell — free

A free spectral resonance suppressor that finds and tames harsh, ringing resonances across the whole spectrum. AU and VST3 for macOS and Windows.

Download Quell free

FAQ

Is a resonance suppressor just a dynamic EQ?
Not quite. A dynamic EQ acts on fixed bands you place yourself, while a resonance suppressor automatically detects resonant peaks across the whole spectrum and ducks them dynamically across many micro-bands. The suppressor finds the problems for you.
Do I need both a dynamic EQ and a resonance suppressor?
Not strictly, but they complement each other. A resonance suppressor handles broadband, shifting harshness fast; a dynamic EQ gives surgical control over specific, known problem frequencies.
Is there a free resonance suppressor?
Yes — Quell is a free spectral resonance suppressor that automatically finds and tames resonances across the spectrum. It is a great free alternative to paid options.

Written by Reinhardt Buhr, a Hamburg-based live-looping multi-instrumentalist and the developer behind Buhr Audio. Quell is his free spectral resonance suppressor — automatic, full-spectrum resonance control at no cost. Download it free here.