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Wednesday, October 18, 2023

Luca Pretolesi - Compressing the midrange of the mix

 

 

 

The term “sidechain compression” brings to mind the technique of using the kick drum to trigger compression on the bass track. But that’s only one way that using a compressor’s sidechain can improve your music production.

In this excerpt from the video, "Luca Pretolesi Mixing Diplo Ft. Miguel,” mastering and mix engineer Pretolesi demonstrates how he adds extra energy to a full mix by using sidechain filtering to target compression to the midrange only.

Special Tools

His tools of choice are a pair of Rockruepel Sidechain One compressors. These units are high-quality hardware mono VCA compressors featuring Highcut and Lowcut sidechain filters controlled by sliders. Luca explains that he adjusts the filters so that each compressor is fed only midrange information into its detector.

Rockruepel’s Sidechain One is a hardware compressor with sidechain filter sliders on the front panel.

“I don't wanna compress the bottom; I want to compress the midrange and bring the midrange in front of the mix,” he says of the technique. He wants the track to sound “a tiny bit more detailed—a little louder.”

The midrange elements in a mix include much of the frequency range of sources like vocals, synths, snare drum, and percussion. The midrange compression allows those frequencies to pop out more. Luca also says that pushing the midrange will also help the mix sound better on devices like phones, tablets and laptops, whose small speakers are midrange heavy.

He uses two Sidechain One compressors, one for each side of the mix. The units have a Link switch that allows them to respond identically to both channels. However, Luca says he prefers unlinking them because it feels more “open.” Instead of compressing the left and right, he sets the compressors to mid/side mode.

Compression Hog

The reason for using a sidechain to filter out the bottom end of a track before it hits the compressor is that low frequencies will disproportionately trigger a compressor compared to the rest of the frequency spectrum.

If your song has a pounding kick and bass, it will cause more compression than you might want. Even when you intend to compress the whole mix, you might want to filter some of the bass in the sidechain to keep the compressor under control. Many hardware and software compressors offer sidechain filtering for the low end.

Since Luca only wants to compress the midrange, he slides the Lowcut filter high enough on each of the Sidechain One units to keep the bass from reaching the detector. He also sets the Highcut filter to cut the high-end frequencies from the sidechain.

Why cut the highs? He says compressing the top will impact his flexibility to apply expansion there subsequently and reduce the feeling of movement in the mix.

By filtering the compressors to only respond to midrange energy it will reduce the peaks so that the compressor’s makeup gain can raise it without those peaks jumping out of the mix. He’s essentially boosting the proportion of midrange in the signal compared to the lows and highs.

”You're gonna feel the song come in front a little bit,” he says. “It’s kind of glued together, but not glue in the old-style SSL, where everything is just moving and bouncing.”

Alternatively, you could boost the midrange using EQ, but it would be a static change, rather than a dynamic one.

Attacking the Music

For settings, Luca recommends a low ratio of 2:1 for compressing a mix. He says if he’s using the technique on a drum bus, he might go up to 4:1.

He sets the attack slow—he doesn’t want to squash the transients. He sets the release fast so that the compressor will let go after attenuating one transient and not impact the following one.

Luca stresses that when you compare your settings you want to keep the levels roughly equal on the meters between the compressed and bypassed versions (something you should always do with an A/B comparison). With both at the same level, Luca says the compressed version will have a perceived boost of 2 or 3 dB due to the midrange sounding more upfront.

What You Need

You don’t need two mono Sidechain One compressors for this technique. You can use a stereo compressor plug-in if it lets you filter both the top and bottom of the internal sidechain signal. If you want to set it up even closer to Luca’s setup, you could use a dual mono instantiation of the plug-in and set it to mid/side mode.

 

While many compressor plugins let you to filter the low end, the ones that offer both low-cut and high-cut for the sidechain are less common. Some notable examples include the FabFilter Pro C-2 and the Pulsar 1178.

In the sidechain section of the Pulsar 1178, you can choose filter types, corner frequencies, Q values, and more like on an EQ. The difference is that it’s not directly affecting the audio, it’s equalizing the sidechain signal that goes to the detector.

The following example will feature Luca’s midrange compression technique using FabFilter C-2. This screenshot shows its settings (including the sidechain on the lower part of the GUI).

Pro C-2 was instantiated in dual mono and set for mid/side processing to emulate Luca’s technique as closely as possible. The setting created about 2 dB of attentuation.

Here is the excerpt without midrange compression.

Here it is with the compression.

If you focus your listening on the hi-hat and snare, you’ll hear the change more clearly.

For the audio example, Fabfilter Pro C-2 was used in a dual mono instantiation with the Mid/Side option chosen.

Multifaceted

Another option is to use a multiband compressor. Although you’re not using the sidechain for this method, you can accomplish a similar result. You turn off all the bands except one and set its frequency range for midrange only (say, between 300Hz and 2kHz).

For example, you can use the Waves C6 with all the bands bypassed but one. Set the frequency range of that band for the midrange. Start with the attack slow and the release fast, similar to Luca’s settings.

You can set a multiband compressor, such as this Waves C6, set to affect only the midrange.

Written by Puremix Team