Traditionally, the way to achieve doubled vocals was by “double-tracking,” meaning the artist would just record their lines twice. Sometimes however, the singer may not be available for additional recordings, you may be the hired mixer and be sent vocal stems that don’t include doubles, or perhaps the singer is finding it difficult to cleanly overlay the same vocal line twice. The production style may also warrant a clean, “perfect” double, rather than a more organic one. These are all possible scenarios in which creating artificially double tracked vocals would be appropriate.

When controlled vocal doubling is what you’re after, look no further than Waves Doubler. It allows you to create synthetic vocal doubles by duplicating, panning and adjusting the pitch of your original input signal. Taking it further, Doubler also allows you to apply feedback, modulate pitch at different rates and EQ your duplicated vocals using a low-shelf and high-shelf filter. There’s also a convenient output gain fader that allows you to attenuate the plugin’s output level.

Synthetically creating doubles in this way tends to provide results that are very closely aligned since they tend to lack true, natural randomization. For some genres however, like pop and EDM, this type of effect can work particularly well, as clean, present and wide vocals is what you need. Having said that, the variety of controls that Doubler offers provides it with the versatility of more varied and organic sounding doubles.

When it comes to creating organic sounding doubled vocals artificially, perhaps for rock, folk or RnB tracks, the artificial double tracking (ADT) method developed by former Technical Engineer and Studios’ Managing Director Ken Townsend has long been the industry standard.

In the days of recording to tape, you can imagine how time-consuming recording was in general. The issue back then was that engineers had to spend countless hours double-tracking vocals and hope that the timing of the vocals lined up correctly. Ken Townsend came up with the concept behind artificial double tracking (ADT) and it involved using two different tape machines, which initially included a J37 and a BTR2. A duplicate of the audio signal running through the J37 was also sent to the BTR2, which resulted in a delay time of around 100ms. The result was as close as possible to a genuine double track. This delay could then be modulated to create unique effects.

Waves Reel ADT plugin accurately recreates the sound of artificial double tracking that was initially used at Abbey Road Studios on artists like The Beatles in the 1960s.

The best part about Reel ADT is that you can set the Varispeed LFO rate to random, which achieves the natural variation and randomization found in a real human voice. In general, I find this unit does a great job of recreating an analogue tone, which you can further emphasize using the included DRV controls. Another neat feature is that you can create positive as well as negative delay times. You have the choice to push the ADT signal ahead of the SRC signal, which can further open up your creative possibilities. When both signals are centred, you can also create some very interesting slap-back effects that can help push your vocals forward in the mix.

When trying to separate vocal doubles from a lead vocal, the less similar they sound to the lead vocal the more pronounced they’ll be in the mix. One great technique is to double or harmonize a lead male vocal with a female vocal, or vice versa. You could even use a formant shifting plugin like UltraPitch to create a female-esque voice out of a male vocal. This provides the lead vocal with a unique colouring and thickness.

For rock or heavy hitting hip-hop, you can run doubles through guitar amp plugins like PRS SuperModels. By distorting and saturating your vocal doubles, you’ll add bite and aggressive flavour to overall vocal tone. If you want a more subtle effect, applying heavy compression to your vocal doubles can mellow them out and help them sit nicely beneath your lead vocal.

Songs with sparse arrangements often have space that needs filling; vocal doubles along with spatial effects are a great way to do this. Try setting up a rhythmic delay specifically for your doubles or give them their own reverb, creating a cloud in which to cushion the lead vocal. If your doubles are panned wide, you could also pan the reverb wide. Alternatively, you could mono the reverb for the doubles and stack it behind your lead vocal.

The physics behind doubling vocals may seem somewhat complicated, but physics isn’t what makes great music; it’s your personal taste combined with your skill, so just trust your ears and make decisions that sound good to you.

Experiment with delay times and variations in pitch using plugins like Reel ADT, or record vocal doubles yourself. Check your mixes in both stereo and mono and optimize playback as necessary.

When to double track vocals is entirely up to you. You’re now aware that double tracking vocals helps to create width, and one of the most common places to do this is in a song’s chorus. The contrast between a mono vocal in a verse and the filled out stereo field in a chorus is always refreshing. Listen to other songs and see where the artist is using vocal doubles; this is an extremely common effect. You have the tools to create multiple different types of vocal doubles, so try exploring how they can affect your mixes.