Week 126: Linear-Phase EQ vs. Non-Linear EQ...Huh? If you’ve worked with the L-Phase Equalizer and L-Phase Multiband, you know how great they are—but what may not be obvious is why it’s so important that the L-Phase Equalizer offers a non-linear mode as well.
LATENCY Linear-phase equalization introduces much more latency than non-linear mode. Therefore non-linear mode is ideal when tracking, but you can switch over to linear-phase mode when mixing (when latency isn’t as important).
For slower computers, you may not be able to run more than a certain number of linear-phase processors. However, you can avoid this limitation by freezing or bouncing a track using linear-phase EQ, or using non-linear mode.
SUITABILITY FOR DIFFERENT APPLICATIONS Linear-phase EQ is best known for extreme accuracy with “surgical” EQ. If you edit a traditional EQ and the L-Phase Equalizer to settings that give a major treble boost, you’ll almost certainly hear that the linear-phase processed audio sounds more transparent and “airy.” Conversely, the phase shifts that are an inherent part of non-linear equalization can give a particular “character” you may find desirable in some applications.
But also note that linear-phase equalizers aren’t perfect; they can exhibit a phenomenon called “pre-ringing.” (This is inherent in phase-linear operation; it’s not unique to Cakewalk’s implementation.) Normally pre-ringing isn’t an issue, because it becomes audible only at low frequencies with high gain and Q (width) settings. However with today’s hip-hop, EDM, and other bass-heavy musical genres, you may want to add high gain/high Q settings at low frequencies on specific tracks or even on a master, so a linear-phase EQ may not be the best choice for this particular application.
Please refer to the following screen shot, but note that I did a major vertical zoom so you could actually see the low-level pre-ringing. This is why the kick
appears clipped, even though it isn't.
The yellow kick drum waveform shows a gain of 5, with a width of 5, at 100 Hz. You can see a tiny bit of pre-ringing just before the attack.
The blue waveform shows the same kick, also with a boost at 100 Hz, but this time the gain is set to 10 dB with a width of 10. Now the pre-ringing is visually obvious, and if you listen carefully you’ll hear a “swooshing” sound.
The green waveform again has a gain of 10 dB and width of 10, but uses the L-Phase Equalizer’s non-linear mode. There's no pre-ringing prior to the attack.
To hear what this sounds like, go to
www.craiganderton.com, click on the Demo tab, and play track #3 in the Playlist. The first measure uses non-linear mode, while the second measure uses linear-phase mode. Both EQs are set to 200 Hz with a Gain and Width of 10. Unless you’re listening over laptop speakers, you should hear the slight pre-ring during the second set of four kicks.
In most applications, pre-ringing will not be an issue, or even audible. But if it is, there’s a simple solution: Set up Aux Tracks or Patch Points, and use the L-Phase Multiband as a crossover that splits the high and low frequencies.
Setup using Aux Tracks to split the signal into two L-Phase Equalizers You can create a crossover split anywhere. Just remember to solo the appropriate band, and set the ratio to 1:1 so there's no compression. The L-Phase Multiband's linear phase crossover is perfect for this application, in fact, for any crossover application linear-phase processing is by far the best choice.
L-Phase Multiband settings to split the audio into lows and highs for subsequent processing by the L-Phase Equalizers. Send the highs to an L-Phase Equalizer in linear-phase mode, and the lows to an L-Phase Equalizer in non-linear mode…you'll have the benefits of linear-phase equalization where it matters the most, and zero pre-ringing.
BUT WAIT…THERE’S MORE! Aside from the option of choosing two different modes, don’t overlook the other outstanding features of the L-Phase Equalizer: being able to do mid/side EQ (among other talents, this is essential when mastering for vinyl), and EQ the left and right sides of a stereo signal independently. Recently I was given a mix where the drum track was premixed and sounded great, but the hi-hat was too “hot.” Fortunately, it was panned considerably to the right (audience perspective), so I used the L-Phase EQ to reduce the highs on the right channel but not the left. Again…problem solved.