Dynamic EQ

What it is

A dynamic EQ is an equalizer in which each band can change its own gain depending on the level of the signal in that frequency region. Each band behaves like a small compressor (or expander) that acts only on a bell or a shelf: when the energy in the band exceeds the threshold, the cut (or boost) kicks in; when it drops, the band returns to neutral.

The difference from a multiband compressor is structural: a multiband splits the signal with crossover filters into adjacent bands and compresses each whole band; a dynamic EQ leaves the signal intact and applies a single EQ curve that moves. The result is more surgical (you can work on half an octave at 3.2 kHz without touching 2 or 5 kHz), with fewer phase artifacts and no crossover bands to align.

When to use it instead of a static EQ

• The problem exists only at certain moments: a boomy bass note, a vocal that gets harsh only on high notes, a guitar that flares up at 2.5 kHz only in loud passages.
• A static cut would make the sound hollow in the moments when the problem is not there.
• You need a de-esser on a precise zone (5–9 kHz) with a bell shape instead of a shelf.
• You need spectral ducking: lowering 2–4 kHz of the guitars only when the vocal is singing (external sidechain).
• In mastering: taming a resonance peak in the mix that appears only in the chorus.

Parameters

• Frequency, Q, band type: as in a parametric EQ. Q 2–6 for pinpoint problems; Q 0.8–1.5 for wide areas (mud, harshness).
• Threshold: the level above which the band starts to act. Many EQs (FabFilter Pro-Q, TDR Nova, Waves F6) show the level of the band in real time: set the threshold so that the band works only on the peaks of the problem.
• Range / dynamic gain: how much it can cut (or boost) at most. Typical corrections −3/−6 dB; de-essing −4/−8 dB; spectral ducking −2/−4 dB.
• Ratio: present in some EQs (Nova, F6). 2:1–4:1 for gentle corrections, 8:1 or more for a ceiling-like behavior.
• Attack: 1–10 ms for sibilance and harshness; 10–30 ms to let the transient through and control the body (e.g. bass boom).
• Release: 50–150 ms for vocals and melodic instruments; 100–300 ms on low frequencies (below 150 Hz a release that is too short causes distortion because the gain follows the waveform).
• Sidechain and detection filter: by default the band listens to its own zone; it can be made to listen to another track (external sidechain) or another frequency.
• Expansion mode (upward/downward): the band can also boost when the signal exceeds the threshold (emphasizing the snare attack at 4 kHz only on loud hits) or cut when it falls below (cleaning up bleed).
• Static + dynamic: in Pro-Q you can have a band with static gain and a dynamic range that is added to it; useful for “a little presence always, less when there is too much”.

Procedure

1. Find the problem with a static EQ (narrow sweep at +10 dB, Q 6–8) and note the frequency and Q.
2. Create the dynamic band with a cut range of −6 dB and a high threshold (the band is not working).
3. Lower the threshold until the band moves only when you hear the problem. On average the band should sit at 0 dB most of the time and drop 2–6 dB on the peaks.
4. Adjust attack and release by ear: if the sound “pumps” or you hear the cut opening and closing, lengthen the release or reduce the range.
5. Compare against the bypass at matched volume and always in the mix.

Starting settings

Sidechained dynamic EQ

Spectral ducking is the surgical version of classic ducking. Vocal/guitars example: insert the dynamic EQ on the guitar bus, enable the external sidechain from the vocal, and create a bell at 3 kHz, Q 1, with a range of −3 dB. When the vocal sings, the guitars lose 2–3 dB only in the intelligibility zone; when the vocal is silent, they return full. The same scheme applies to kick → bass (50–90 Hz), vocal → pad (1–4 kHz), vocal → reverb (2–6 kHz).

In FL Studio the Fruity Parametric EQ 2 has no dynamic bands: use external plugins (the free TDR Nova, FabFilter Pro-Q, Waves F6) and send the sidechain signal from the mixer (right-click the send cable → “Sidechain to this track”).

Common mistakes

• Using it as a static EQ with the threshold too low: the band stays down 6 dB all the time and the benefits are lost (and it adds artifacts).
• Releases that are too fast below 150 Hz: distortion and bass “flutter”.
• Too many dynamic bands working together: the tone keeps changing and the mix loses stability.
• Wide, deep dynamic bands on the bass of the master: a pumping effect similar to a poorly set multiband.
• Not checking the reduction graph: if the band never returns to 0 dB, the threshold is wrong.