In this lesson
Dynamic EQ or multiband: match the problem
Both turn part of the spectrum down when it gets loud. They differ in the shape of the cut, what the detector hears and what happens at rest.
· 7 min read · Lesson 22 of 44 in Mixing & Mastering
In short
- Before choosing a processor, find out how wide the problem is and when it happens, then pick the tool whose cut has that shape.
- A narrow ring on a few notes suits a dynamic bell, because its detector and its cut can both be as narrow as the ring.
- A broad region that swells in loud sections suits a multiband band, but remember that its crossovers shift phase even when nothing is being compressed.
In this lesson (8)
The fix that dulled every chorus
The chorus vocal stings on two notes, the high ones, where a harmonic lands on a ring near 3 kHz. You put a on the vocal, pick the upper-mid band and pull its threshold down until the sting goes. It works on those two notes. Then you notice the rest of the chorus: every loud line has lost a little presence, and the vocal seems to sit further back than it did in the verse.
The multiband did what it was set up to do. Its band was wider than the problem, and its detector could not tell the ring from the healthy brightness around it. A bell at the same frequency would have cut on those two notes and left most of the chorus alone. A broad problem would have favoured the multiband.
Why it matters
Same idea, different shapes
Both processors turn part of the spectrum down when that part gets loud, so they are easy to treat as one tool with two interfaces. They differ in where they cut, what they listen to, and what they do to the signal while nothing is being cut. Pick the wrong one and you fix the problem while changing a lot of sound that had nothing wrong with it.
A dynamic band is a peaking or shelving filter, the same design a static parametric EQ uses (Zölzer, 2011), with its gain knob turned by a level detector instead of your hand. A multiband splits the signal into bands with crossover filters, gives each band its own compressor, and adds the bands back together.
The science
Cut shape, detector and crossovers
The cut a dynamic bell makes has the shape of the bell. Its width is set by Q, so it can be as narrow as a single . A multiband band's cut is as wide as the band, and its edges are the crossover slopes. Those slopes are gradual, so on a narrow band they overlap and the band never reaches its full cut.
The detector matters as much as the cut. In many dynamic EQs the detector listens through a band-pass at the band's own frequency and width; here it is drawn as a second-order band-pass at 3 kHz with Q 4. The multiband detector hears everything in its band. Give both a 3 kHz ring and a bright 4 kHz consonant or harmonic at the same level, and the results split.
The dynamic EQ reacts to the ring and mostly ignores the 4 kHz peak. The multiband reacts to both equally, so it turns down the whole band on loud words that never rang, which is how the chorus in the hook lost its presence.
The third difference shows up when nothing is being compressed. Many multiband compressors use Linkwitz-Riley crossovers, which add back to a flat level but behave like an all-pass filter: the shifts around each crossover frequency (Linkwitz, 1976). A peaking filter at 0 dB gain is a straight wire, so an idle dynamic bell changes nothing. On one track the crossover phase shift is hard to hear. It matters when the processed track is mixed with an unprocessed copy, the same trap the lesson on filters describes. crossovers avoid it, at the cost of and some pre-ringing.
Multiband is the better shape when a broad region swells with level, such as the whole 2 to 8 kHz range of a mix getting hard in loud choruses, or the low end of a bass blooming across several notes. Multiband compressors make it easy to give the lows a slower release than the highs. The tools also overlap: many dynamic EQs can draw wide bells and shelves, and many multiband compressors let you place crossovers close together.
The first step is always the same: find the problem by ear and judge how wide it is. Use the sweep below to practise it.
Listen
Find a frequency by ear
A narrow boost you can sweep across a synth loop or a real mix. Move it slowly, stop where it sounds worst, then check the number.
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Start with your speakers or headphones low.
Try it
One ring, two tools
You need a dynamic EQ and a multiband compressor. Several DAWs ship only one of the two, so you may need a free plugin for the other.
0 of 6 steps done
On the harsh notes both versions remove the sting. On the clean notes the multiband keeps working and the presence drops, while the dynamic bell sits at zero.
Common mistake
Choosing by the interface
Reaching for multiband because it looks like the more serious tool is the first mistake, and so is the opposite: stacking five narrow dynamic bells to tame a mix bus that gets harsh across an octave or two. Each bell catches one slice at its own moments, so the tone shifts in a way one broad band would avoid.
The second mistake is setting the threshold on the worst note and never checking the others. A dynamic processor that cuts on every note is a static EQ with a detector attached. Check the meter on the passages that sounded fine. If it moves there, raise the threshold or narrow the detector.
Takeaway
Describe the problem first
Before opening either plugin, describe the problem in three parts: how wide it is, when it happens and what should trigger the fix. A narrow ring on certain notes points to a dynamic bell. A broad region that grows with level points to a multiband band. If the trigger is another track, such as a vocal that needs room in the guitars, key the processor from that track, as in the lesson on sidechain routing. Whichever tool you choose, the test is the same: check the passages that were already fine and keep the setting only if they still sound the same.
Multiband compression
Splitting a signal into frequency bands with crossover filters and compressing each band on its own.
Dynamic EQ
An EQ band that cuts or boosts only while the level in its band, or in a key signal, passes a threshold, and stays flat the rest of the time.
Compressor
A processor that turns a signal down once it goes above a threshold. The ratio sets how much: at 4:1, every 4 dB over the threshold comes out as 1 dB over.
Resonance
A frequency where a system rings or builds up energy. On a filter, the resonance control boosts a narrow band around the cutoff.
Phase
Where a wave is in its cycle at a given moment. Two copies of a sound that are out of phase partly cancel where one rises while the other falls.
Linear phase
A filter that delays every frequency by the same amount, so the waveform shape is kept. The cost is latency and a little ringing before sharp hits.
Latency
The delay between doing something, like pressing a key, and hearing the result.
3 questions
Check yourself
Sources
Show all 2Hide sources
- Linkwitz, S. H. (1976). Active crossover networks for noncoincident drivers. Journal of the Audio Engineering Society, 24(1), 2-8.
- Zölzer, U. (Ed.). (2011). DAFX: Digital Audio Effects (2nd ed.). Wiley.
Next lesson · 23 of 44
A vocal pocket that opens when the singer singsStatic cuts thin out the band whenever the vocal rests. A dynamic EQ keyed from the vocal dips the clashing range only while the singer is singing.Previous: Sidechain lets one track control another
Written by Virzy Guns
Songwriter and producer, founder of Virzy Guns Production. Now building HealingWave.