If there’s one thing that gives ‘sounds like a record’ fairy dust to vocals and instruments, it’s double tracking. Adding a third part seems like a good idea, but the reason it sounds great is far more interesting than just more is more. Hear it for yourself.
Engineers and songwriters of a certain age will remember the first time they double tracked a vocal. For many, it will have been after working out how to overdub with two cassette decks or open reel machines (in the pre internet era, everyone was their own pioneer), or when they finally got their hands on that shiny new 4 track Portastudio. The impossibly expensive-sounding gloss it afforded on budget recordings was a revelation and certainly addictive. The music listening public are also in love with the sound albeit without even realising it - certainly they know when something sounds like a record or when something sounds slightly more home-spun. As a production trick, double tracking has established itself as one of those sounds that screams radio-ready.
Double Tracking
The technique of recording the same part twice gives rise to the familiar double-tracked sound delivering rich, natural chorusing that lends itself well to the ultimate organic instrument: the human voice. It must be said, however, that more recent tools are a world away from the canned chorus or doubling effects of old, and are well worth checking out when real doubles aren’t possible.
The aim is to record the second part as closely to the first in terms of pitch and timing to achieve the effect. Curiously, some singers’ ability to clone themselves can give rise to partial phase cancellation owing to parts that periodically sum and cancel at certain frequencies. The fact here is that there is no one ‘true’ part; they both deviate from the imagined datum of perfect tuning and timing.
Triple Tracking Versus Double Tracking
In a stereo mix, double tracking can be used for either for widening with a panned duplicate, such as on guitars, or for thickening ‘down the middle’ on main inputs such as the vocal. A combination of both aims can also be achieved. Demonstrating these two uses, Sonnox’s VoxDoubler actually comes in two plugins covering both bases.
In triple tracking, a third part is recorded to achieve a slightly different effect. On the understanding that two parts are more likely to cancel and sum with each other than are three, triple tracking can be used as a thickening effect that is different to double tracking by reducing the chance of phasey summation and cancellation. Hear the effect for yourself below:
Fader at 0dB.
With subjective equal balance established with single remaining at 0dB. Both faders then faded back by 3dB to give the same subjective level as the single.
Third take with subjective equal balance established against the doubles. All three tracks then faded back by another 3dB to give the same subjective level as the double.
A final result, this time in the context of a three part harmony, with subjective balance and some reverb. Each part’s tracks are panned hard left, centre, and right. Other more naturalistic placements could see each part occupying its own place in the stereo field.
What Does Triple Tracking Do To Audio?
Above are the waveforms (zoomed vertically and horizontally) as recorded for the Vocal 1 triple track. Tracks A and C would have briefly cancelled each other out, but the presence of track B serves to fill in the ‘gaps’. A third part with 90 degrees difference at this point would not have made any difference. The aesthetic result can be heard in the examples above. Triple tracking’s more complex summation provides a smoother alternative to double tracking’s overt chorusing.
Refining Replicates
As can be heard above, some balancing is needed to sit a replicated vocal part at the same subjective level as a single one. For a more subtle result, tracks can be balanced in behind the first take. Overdubs’ phrasing and timing becomes more critical with the sung word, with ‘oohs’ and ‘aahs’ being more forgiving. With lyrics, any ragged phrasing can be helped along with alignment tools, or even slightly over de-essing all but one track. The classic technique of under-enunciating ‘s’ and ‘t’ sounds still stands up as one of the quickest ways to achieve tight replicates. Where a tighter low end is needed, the engineer can experiment with HPF on replicates using higher than normal turnover frequencies.
The Magic Number?
While triple tracking could be misconstrued as over-production, there are both technical and artistic reasons to employ this technique. What it is not is ‘doubling with more’, instead offering an alternative with lushness with less of the cancellation that can give the game away on doubles. The latter can be helped with judicious use of the fader, but triples randomise the interactions between tracks and can be more easily balanced in equal measure for thickening.
With essentially no upper limit on available tracks in most DAWs, there really isn’t much reason not to try triple tracks over doubles for thickening, assuming the performer isn’t starting to waver through tiredness, indifference, or both. Not only that, it will bring a smile to the face of any engineer who thought they had heard it all before. These two things combined make it worthy of exploration for those who are yet to try it.