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Mixing - Working with the Mighty Mult

July 18, 2012

Fig. 1. A mult for a lead vocal track is removed from the mix bus and sent pre-fader to a Lexicon LXP Native Reverb plug-in in Digital Performer. The Waves H-EQ Hybrid Equalizer plug-in pre-conditions the mult’s reverb send, rolling off highs.
Which old-school engineering routine can be used to increase headroom, pre-condition effects and sidechain inputs, and simplify writing automation during mixdown? Answer: the mult. This simple but versatile procedure is often overlooked, but it can be a terrific aid for a variety of mixdown tasks.

For the uninitiated, “mult” is jargonistic shorthand for both the words “multiply” (the action) and “multiple” (the result). Multing a track multiplies it by making an exact copy of it. The result is a mult, or multiple, of the track.

In the analog realm, a mult is created by routing a track to a patchbay in which the top row of jacks is half-normalled to the bottom row. Inserting a patchcord into a top jack creates a new path for the signal while also preserving its flow to the jack below it. Splitting the signal into two paths in this manner allows you to process each copy of the signal differently.

Multing a track inside your DAW is even easier—just duplicate it. You can then route and process each of the tracks—original and copy—differently.

In this article, I’ll show you a few ways to use mults to turbo-charge your mixes and simplify your workflow. For simplicity’s sake, I’ll assume you’re mixing inside the box. Ready? Let’s split!

Goose the Level The most basic use of a mult is to give a track more level—free of clipping— after it’s already run out of headroom. In the final stage of mixing, for example, you might realize that the lead vocal track sounds too quiet. If its level is already close to clipping and the backing tracks are mixed to perfection, you’ve got a problem: Either raise the lead vocal track further and suffer the clipping distortion, or lower all the backing tracks and skew your carefully wrought balance. The solution is to mult (duplicate) the lead vocal track, assign the mult to an unused mixer channel, and raise its fader until the vocal sounds loud enough. (You must have some remaining headroom on your mix bus in order to accommodate the extra level.) Be sure to add the same signal processing to the mult as was applied to the original track so that they sound the same.

Double-track It To add pizzazz to lead vocals in the mix, apply pitch-correction (using Antares Auto-Tune or Celemony Melodyne, for instance) to its mult but not to the original track. The dynamically shifting differences in intonation will create a lush automatic double-tracking (ADT) effect superior to what any chorus plug-in can fashion. By riding the mult’s fader, you can introduce the ADT effect to different degrees during various sections of the song. Generous fader boosts during choruses breeds excitement.

Pre-condition Effects Say you’ve routed the lead and background vocals (BVs) to the same bright hall reverb. The BVs sound beautifully present, but the lead vocal sounds too bright. The solution? Kill the lead vocal’s reverb send, and mult the track. Pull the mult’s fader all the way down, bus the mult pre-fader to the reverb via an effects send, and aggressively roll off the mult’s high frequencies with an EQ plug-in instantiated pre-fader (see Figure 1). The lead vocal’s reverb will now sound suitably dark, while the timbre of the dry (original) lead vocal track—and that for the BV’s reverb return— will remain unchanged. This technique is often referred to as “pre-conditioning” an effect because it changes how the effect will sound on a source-by-source basis.

You can also use a mult to transform a compressor into a vocal de-esser. (Compressors with fast time constants work best for de-essing.) The crux is to pre-condition the compressor’s sidechain. Slap the compressor on the original vocal track. Mult the vocal, but don’t add a compressor to the mult. Using a prefader EQ plug-in on the mult, drastically cut all frequencies below 5kHz and boost generously above 5kHz. Plunge the mult’s fader all the way down, and send the mult pre-fader to the sidechain input for the original vocal track’s compressor. The sidechain will now “hear” a horribly bright vocal that exaggerates any sibilance, but the vocal will sound normal in the audio path. Set the compressor’s threshold to initiate compression only when sibilance occurs. Voilà, the compressor acts like a de-esser!

Simplify Writing Automation A male lead vocalist will sometimes sound too muddy during verses when he’s singing near the bottom of his range and too bright when he’s hitting high notes in each chorus. You could automate dynamic EQ changes throughout the song, alternately boosting and cutting highs as needed. Alternatively, you could mult the lead vocal track and be done in a fraction of the time. EQ the original track to sound brighter (for use during verses) and cut the mult’s high frequencies (for use during choruses). Automate the respective channel mutes for the original track and mult so that the appropriately EQ’d vocal turns on during each song section. If you later decide to change the vocal’s timbre during the chorus, for example, you’ll only need to make a static change for the mult’s EQ. Had you not multed the lead vocal track, you would’ve had to overwrite its dynamic EQ changes on each and every chorus. Just another example of how mults save the day!

Michael Cooper ( is a mix and mastering engineer based in Oregon, and a contributing editor for Mix magazine.

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