Note the ability to make pinpoint-precise fixes in both Ozone's Izotope Dynamic EQ (Fig. 1— top) and Fab Filter's Q3 (Fig. 2 — bottom).
First, let me define what a dynamic EQ is, since it's often confused with a multiband compressor. Essentially, a dynamic EQ is an EQ (with all of the normal attributes: HPF, LPF, notch, and band-pass filters) that also has the added ability to compress a frequency band much like a standard multiband compressor.
On the surface, you might think there's not much different between the two, but I'm going to advocate for you to not be fooled by this generality. If you're not sure what a compressor is or need a refresher, I invite you to review my previous Dojo articles, in the June and July 2020 issues, discussing that very subject. You can also visit my website, bryanclarkmusic.com, for more info. With that said, the Dojo is now open, so let's begin.
"Wouldn't it be nice to have something that would only go to work when those ice-pick frequencies are happening and leave everything else alone?"
I love using dynamic EQs to tame intermittent problem frequencies and pesky gremlin-like spikes on individual tracks within a session (acoustic guitar, electric guitar, bass, vocals, snare, synths, etc.), and I have found they can do this with much more transparency than using a multiband compressor. Izotope's Dynamic EQ (in Ozone) and Fab Filter's Q3 are excellent examples of dynamic EQs (Fig.1 and Fig. 2).
Let's say, for example, your latest and greatest guitar solo has significant parts that sound abrasive, it's making your ears get fatigued, and has that kind of "ice pick in the forehead" tone (to quote Frank Zappa). Usually you're going to want to examine the 2.5 kHz to 3.5 kHz part of the frequency spectrum and start subtracting some of that harshness. However, if you do that using a standard EQ, you're also subtracting those frequencies from the entire solo—even the parts that don't have those annoying artifacts—and thus you could be changing the overall tone of your guitar solo. Wouldn't it be nice to have something that would only go to work when those ice-pick frequencies are happening and leave everything else alone?
Unlike most multiband compressors, Waves C4 offers expansion, but it also limits the audio spectrum to just four bands.
Here's why I prefer using a dynamic EQ in this scenario: It's more surgical and more transparent. Most multiband compressors generally divide the audio spectrum into three or four bands (Fig.3). You simply set the crossover points to bookend the frequency area(s) of sonic annoyance, and then, by using ratio (4:1, etc.), reduce the aural offenses when they cross over the threshold of the compressor. Dynamic EQs, on the other hand, also do this, but with much more flexibility by increasing the standard three or four bands (or points) to eight or 10, and you can insert the point directly on the offending frequency(s) rather than having to bookend like a multiband compressor. This can be handy if your track has multiple low-end, midrange, and high-end peaks that you need to wrangle. Pro tip: If you have a plethora of frequencies that you're trying to "fix," it's a good sign that you might not have recorded it as best as possible.
Generally, traditional multiband compressors only reduce audio signal once they start working and don't offer the ability to expand or boost the frequencies if you ever have the need. Although, to be fair, a few—like Waves C4 and C6—do offer expansion capabilities. Dynamic EQs, however, are just as capable of boosting the frequencies as reducing them, thus giving you more options to bring out little details that might normally get buried in a traditional multiband compressor.
Finally, and most importantly for me, dynamic EQs use the actual level (or gain) of the frequencies in question rather than using ratios (4:1, 8:1, 12:1, etc.) like compressors do. Because of this design, dynamic EQs are much more transparent and can either reduce or expand frequencies with much less coloration, to get the closest to an ideal recording of your track.
Until next time, be well, be curious, and have fun.
Here are three scenarios to try that will help you learn how to use a LPF in your mixes.
Scenario 1: acoustic guitar and vocal (or second guitar).
In this situation, you should record your acoustic guitar and your vocal separately, on two different tracks, and not at the same time. If you don't sing, then just play a solo to go along with your acoustic guitar track. First, in your DAW, instantiate and EQ on your acoustic guitar track with an LPF and set it for a -24dB/octave with a center frequency somewhere around 2800 kHz (Fig.1). Next, sweep the frequency to the left and the right and notice how the guitar track will lose its top end (“air") and begin to sound warm. It should immediately start sounding a bit more lo-fi, or like an old recording from last century. Find a frequency range that sounds good to you but is still cutting out a significant amount of the high frequencies and transients of the acoustic guitar. For the vocal track (or your solo track), don't use any EQ at all. Just let it be au naturel. Now listen to both tracks at the same time while toggling the acoustic track's LPF on and off. What you should immediately notice is the vocal track (solo track) will be much more in focus and really have some distance and dimension from the acoustic track when the LPF is active. Season to taste.
Fig. 2
Scenario 2: finding more “space" between the drums and the lead guitar tracks.
Especially in rock music, a significant amount of the drums' energy can come from those cymbals that the drummer is bashing on relentlessly. Cymbals can kill a mix faster than Kryptonite, and they can obscure the subtle pick attacks of lead guitar parts and solos. In this situation, try putting an LPF on the drum overhead tracks, or the main drum track if you are playing with loops, or software instruments, etc. Start around 6,500 kHz (Fig. 2) with -48 dB/octave and sweep around until the drums start to sound warm and the cymbals aren't stepping all over the guitar parts. There are many complex ways to achieve this result, but we have to start somewhere and we want to keep it as simple as possible while putting you in the right territory. For a good reference, listen to U2's “Beautiful Day," and notice how the cymbals don't fatigue your ears or take over the mix.
Scenario 3: using an LPF to make room for a vocal in a mix.
Have a look at Fig. 3 and pay attention to the far right side of the audio spectrum. Notice how the aggressive LPF is literally cutting off high frequency information above 20 kHz. This brick wall (greater than -96 dB/octave) setting can be used to your advantage—especially if your voice (or your singer) has a lot of breathiness and air, but it's getting lost in the mix within the rest of the band. Or perhaps you want to make the mix sound more vintage.
Fig. 3
What we want to do here is sum all of the band tracks except the vocal to a new bus (or track), and then put an LPF on the newly summed track. Here is where you'll want to play around and move quickly to see if you can find that sweet spot between having the band track sounding too dull and giving the vocals the right amount of air or breathiness. Once you dial it in, you can toggle the LPF on and off to hear how the vocals can come in and out of focus.
Don't get frustrated when trying these techniques. It might take some time to really start hearing the differences, and to find ways to use LPFs to your advantage.
Until next time.