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Use Dynamic EQs to Tame Your Tone

9/17/2013

Fig. 1. The Brainworx bx_dynEQ V2 dynamic equalizer plug-in de-booms an acoustic guitar by cutting at 222Hz whenever an E note is played at the 2nd fret on the instrument’s 4th string

THE NEXT time you’re faced with a track that seesaws wildly in timbre during mixdown, don’t reach for EQ automation. You’ll be twiddling knobs for all eternity, alternately boosting and cutting as the track’s tone changes. Slap a dynamic equalizer on the track instead. After a quick setup, the dynamic equalizer will automatically perform all the filter boosts and cuts needed to give your wandering track a consistent tone.

Dynamic equalizers act like a splitband compressor or expander, compensating for too much or too little energy in one or more frequency bands on an as-needed basis. In this article, I’ll show you how to use dynamic equalizers to corral erratic tone. For simplicity’s sake, I’ll use the Brainworx bx_dynEQ V2 mid-side plug-in in its single-band stereo mode to illustrate my points.

Fig. 2. bx_dynEQ V2 softens a female vocalist’s shrill-sounding high range.
Subdue Boomy Guitar Acoustic guitar often sounds clear and sparkly on high notes, but boomy when the 4th string is played on lower frets. To keep the guitar’s tone from swinging like a yo-yo, instantiate bx_dynEQ V2 (I’ll call it dynEQ henceforth for brevity’s sake) on the track’s insert and set the plug-in to Regular (stereo) mode. Drag the boost/cut switch down to implement EQ cut.

In dynEQ’s audio path, select the center frequency for the boomy guitar formants you wish to tame. In the plug-in’s internal sidechain, set the fundamental frequency for the specific guitar note that excites the boomy formants. Don’t be surprised if the frequencies for note and formants differ. For example, an E note played on the 4th string’s second fret has a fundamental frequency of roughly 165Hz, but the boominess it engenders might be centered almost a half octave higher. In this case, set the internal sidechain to 165Hz (the E note) and the filter in the audio path to around 222Hz (see Figure 1). Select a narrow peak filter for the sidechain so that notes substantially higher or lower than E won’t trigger equalization. (You’ll probably need to broaden the filter enough to span several neighboring notes.) The filter for the audio path will typically need to have a much wider bandwidth than that for the sidechain. With these settings, whenever dynEQ’s sidechain senses an E note or neighbor tones are played on the guitar, it will initiate a broad cut centered at 222Hz.

To ensure dynEQ doesn’t cut too heavily, set its maximum gain control to around 6dB and its Factor control—a gain multiplier—to roughly 0.5. Try dialing in a 9.7ms attack time and 50ms release for starters. Shorten the attack time if boomy notes sneak past the plug-in before it reacts. Fine-tune dynEQ’s threshold so that equalization cut only occurs when the guitar would otherwise sound boomy, letting sparkly notes pass through the plug-in unprocessed.

Fig. 3. bx_dynEQ V2 automatically boosts 222Hz when a solo violin plays very high notes, fattening the tone.
Tame Shrill Vocals Some female singers sound warm in their lower range, only to blare like a siren when your song’s chorus kicks in. You can soften her shrieking by using a technique similar to what you’d use to moderate an acoustic guitar’s boomy tone. In this case, however, set filters for both the audio path and sidechain to the same center frequency and bandwidth: between 2.5 and 4.5kHz (depending on the offending frequencies), using a broad peak filter (see Figure 2). An 18ms attack time and roughly 280ms release usually work well on vocals for this application. Set maximum gain to cut no more than around 4dB on peaks, or vocal presence might be suppressed too greatly.

Fatten High Violin Notes A solo violin that thins out when playing in its high register can be fattened by boosting in dynEQ (boost/cut switch set to boost) with a broad peak filter centered around 222Hz (see Figure 3). To keep low, full-sounding notes from thickening further, select in dynEQ’s internal sidechain either a high-pass filter with a 24dB/octave slope and roughly 2,000Hz corner frequency or a bandpass filter centered at about 3.8kHz. The sidechain’s filter will help prevent low notes from exceeding the threshold and triggering EQ boost. High notes that the sidechain filter doesn’t attenuate, on the other hand, will automatically trigger EQ boost at 222Hz, adding appealing girth. This is just one more example of how dynamic equalizers free you from the tedium of automating EQ—and deliver better mixes.

Michael Cooper is the owner of Michael Cooper Recording in Sisters, Oregon (myspace.com/michaelcooperrecording), and a contributing editor for Mix magazine.

 
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