Definition
A double (double tracking) is a second performance of the same vocal part, layered over the first. The small differences in pitch, timing and timbre produce a thicker, wider sound than a single take. A triple adds a third performance. The technique has been widespread since the 1950s (Buddy Holly, Elvis); to spare John Lennon from singing everything twice, in 1966 engineer Ken Townsend at Abbey Road Studios invented ADT (Artificial Double Tracking), which simulated the double with a tape recorder and a variable delay.
Types of doubles
- Tight double: identical to the lead, precisely aligned; reinforces without being noticed. Often in the center or at ±10–20%, 6–12 dB below.
- Wide doubles (L/R): two takes panned to the sides, the lead in the center: this is the classic pop and rock triple (lead + double L + double R).
- Whispered double: the same melody whispered or sung very softly, adds air and intimacy (widely used by Billie Eilish and in modern pop).
- Octave below: adds weight (often 10–15 dB below the lead).
- Octave above: brightness in the chorus.
- “Key word” double: only some words of the line doubled for emphasis (typical of rap: the last words of each bar).
How to record them
- Sing with the lead in your headphones, aiming for the same intention, the same breaths and the same vowels.
- Do at least 3–4 double takes and pick the best.
- Keep microphone, distance and chain the same as the lead (or deliberately different to vary the timbre).
- Side doubles can be sung with less vibrato and fewer ornaments.
Editing
- Alignment: consonants and attacks must coincide with the lead to within about 10–30 ms; use VocAlign, Revoice Pro or manual editing (cuts and time stretch).
- Word endings: the tails of the doubles must close with the lead, not after it.
- Sibilants and plosives: remove or reduce “s”, “t”, “k” in the doubles (fade, clip gain or a very aggressive de-esser): otherwise you hear multiple out-of-phase “s” sounds.
- Breaths: keep them only on the lead.
- Pitch: correct only the clearly out-of-tune notes; too much correction makes the double identical to the lead and the effect disappears.
Artificial doubles
- ADT/modulated delay: a copy of the lead with a 10–40 ms modulated delay (slow chorus); a 1960s effect.
- Micro-pitch shift: a copy at ±5–15 cents, delayed by 10–20 ms (e.g. the “doubler” effect in many plugins: Waves Doubler, Soundtoys MicroShift).
- Shifted copy (Haas): a copy with 15–30 ms of delay, panned the opposite way. It works in stereo but collapses badly in mono (comb filtering).
Artificial doubles don't replace real ones for the “thick” sound of a section, but they are useful for varying the color.
Where to use them
- Verse: single lead (more intimate) or tight double.
- Pre-chorus: tight double or doubles on key words.
- Chorus: triple (lead + L/R), octave below, harmonies.
- Rap: doubles on the rhyming words and on ad-libs.
The contrast between a single verse and a doubled chorus is one of the simplest tools for making the chorus grow.
Mixing
- L/R doubles with HP at 150–200 Hz, compression equal to or heavier than the lead.
- Level: side doubles 4–10 dB below the lead.
- Reverb equal to or slightly greater than the lead.
Practice exercise
Record a chorus in four versions: single lead, lead + tight double, triple (lead + L/R), triple + whispered octave below. Align the doubles and remove the sibilants. Listen to the versions at equal volume (match loudness) and choose which to use for verse and chorus.
Links
Gang Vocals, Doubles and Mass Choirs, Vocal Stacks, Vocal Production: Comping, Tuning, Timing, Stereo, Panning and Image.