Doubling

Doubling is an audio effect used in music production to thicken and enhance the sound of instruments and vocals. The purpose of doubling is to make the sound fuller and more spacious by essentially duplicating tracks and layering them together.

This can be achieved through various techniques that create the illusion of two identical sounds playing in unison. At its core, doubling gives a heightened sense of richness and dimensionality to the parts being doubled.

The most common doubling techniques used in music production include short delays, chorus effects, pitch modulation, and panning. For example, a lead vocal track may be doubled by adding a 10-20ms delay and then mixing the delayed track subtly under the main track. The added track thickens up the vocal without an audible echo. Similarly, applying a light chorus effect creates a doubling effect by slightly detuning and modulating the duplicated track. More advanced methods like pitch shifting and stereo panning can further enhance the doubling effect.

These techniques work by exploiting the psychoacoustic principles of auditory masking and the precedence effect. The doubled track is masked slightly by the main track so they are perceived as one unified sound. Panning and modulation create a sense of space and movement. When done tastefully, doubling makes the sound full without losing clarity or becoming muddy. Music producers use doubling across all genres from pop and rock to electronic music to give more power and polish to vocals, guitars, pianos, and anything else needing a boost.

The Science Behind Doubling

When two identical sounds are played together, even with subtle differences, the human ear perceives them differently than a single sound on its own. The science of psychoacoustics explains several phenomena that create an effective doubling effect.

One principle is auditory masking – when a dominant sound makes a similar, quieter sound indiscernible. The louder main track masks the subtler double, causing them to be perceived as one cohesive sound. The precedence effect also comes into play – when highly correlated sounds are heard close together, the ear localizes the first arriving sound and suppresses perception of the lagging sound.

Short delays of 10-50ms between the main and doubled track tap into these psychoacoustic principles. At delays under ~30ms, the doubling effect is most pronounced because the lag falls under the threshold of the precedence effect. Longer delays create audible echoes. Likewise, subtle pitch modulation reinforces masking and precedence, making the two tracks fuse together in the ear’s perception.

Chorus effects take advantage of these psychoacoustic phenomena by modulating pitch and timing. The pitch fluctuations are kept miniscule – less than a semitone above and below the original. Small differences in pitch prevent melodic clashes. The modulations in timing are also in the 10-50ms range. This desynchronizes the doubled track just enough to create fullness without mud.

All these techniques mimic the natural doubling effect of two performers or takes being similar but not identical. Human performances have natural variability in pitch and timing. Electronic doubling methods introduce variations purposefully to emulate a realistic double. When delays, chorus, pitch modulation, and panning are combined skillfully, the doubled track becomes one with the original in a pleasing way.

Common Doubling Techniques

While the science behind doubling relies on psychoacoustics, the craft relies on choosing the right techniques and applying them artfully. There are several common methods producers use to effectively double tracks in the mix, whether on vocals, guitars, or other instruments. Using the right approach or combination of approaches is key to creating seamless doubles.

Delay

Applying a short delay is one of the most common and effective ways to double a track in music production. Delay times in the 10-50ms range work best for doubling purposes, as anything longer starts to become audibly detached from the original signal.

Both analog and digital delays can be used to produce doubling effects. Analog tape or bucket brigade delays impart natural chorusing and warmth to the delayed signal. This can sound very pleasing on vocals, guitars, and other acoustic instruments being doubled. Digital delays offer more pristine and transparent doubling for electronic instruments like synthesizers.

Dialing in the ideal delay time requires careful listening and fine adjustments. Start on the low end around 10-15ms and slowly nudge up while paying close attention to phasing and clarity. The “sweet spot” tends to be in the 15-35ms range – long enough to thicken the sound but short enough to avoid distinct echoes. Moderating the delayed track’s level is also important to achieve the right blend with the original part.

Creative delay settings can further enhance doubling results. Adding a touch of feedback on the delay unit can increase thickness, but too much will make it sound more like an effect. Automating the delay time subtly can help the double sound more “human”. Pitch modulation built into certain delays can reproduce the natural variances in pitch of real takes. Getting creative with delay patching can take simple doubling to a more advanced level.

Chorus

Chorus effects are another go-to technique for doubling tracks in the studio. Chorus works by modulating the pitch and timing of the duplicated track to emulate two performers or takes with natural variances.

The rate control adjusts how frequently the pitch and timing shift, generally measured in hertz. For doubling purposes, subtle slower rates around 0.5-5Hz work best. Faster chorus rates sound more pronounced and vibrato-like.

The depth knob controls the amount of pitch modulation, usually measured in cents (100 cents = 1 semitone). Depth around 5-15 cents gives the perfect subtle detuning for doubling. Higher depths begin to sound more warbly and less natural.

Tone knobs shape the uniqueness of the chorus effect. Lower settings sound smoother, while higher settings emphasize the modulations. Finding the right tonal balance is key.

Stereo chorus widens the image by modulating each side differently. This can enhance thickness, but mono chorus has a more focused centered sound that may cut through a mix better.

When tuned thoughtfully, chorus provides lively organic movement to double tracks. Dialing in appropriate rates, depths, and tone is essential to doubling realistically with chorus effects. Used creatively, chorus doubles can bring energy and motion to guitars, keyboards, vocals, and more.

Pitch Shifting

Shifting the pitch of the doubled track slightly up or down is an effective way to thicken the sound. The pitch change should be subtle – no more than a quartertone or semitone above or below the original track. This introduces natural harmonic variation to reinforce the doubling effect.

Managing pitch drift is important when using pitch shifting to double. The doubled track should hover closely around the original pitch and not drift too sharp or flat. Quick pitch wavering can work, but a consistent pitch discrepancy will sound awkward.

Harmonizers and pitch modulation effects allow for controlled pitch shifting when doubling. Simple pedals like the Eventide PitchFactor offer dedicated doubling algorithms to add pitch-shifted layers tuned precisely to the key and chords. More advanced pitch modulators from brands like Soundtoys allow shaping unique modulation curves for doubling.

Automating the amount of pitch shift can make doubles sound more “human”. Subtly wavering the pitch offset over time emulates natural pitch instability in real takes. Varying the mix level of the pitch shifted double is also important for transparent blending.

Used in moderation, pitch shifting is a powerful tool for natural thickening on vocals, guitars, synths, and more. A touch of controlled pitch waivering or offset goes a long way in creating realistic and pleasing doubles. Pitch modulation widens the palette of doubling colors available to mix engineers.

Panning

Panning the doubled track to the opposite side of the stereo field can provide an effective sense of space and width. This technique places the original track on the left and the double on the right, or vice versa.

Widening the stereo image with panning can make doubles sound bigger and more enveloping. The doubled layer appears to “surround” the dry track when panned opposite. This also leaves the center clear for other lead parts in the arrangement.

However, extreme hard panning does come with potential downsides. Big pan separations can cause phase issues as the signals interact. Panning may also isolate doubles too drastically from the original track. Subtle pans under 50% often work better.

Moderation is key for maximizing the benefits of panning doubles. Try different pan positions and listen critically to phase coherence and imaging. Often a subtle pan between 20-40% opposite the original track gives the right sense of space without being disruptive.

Automating the pan position over time can make doubles sound more dynamic. Slight moving pans make the double track sound more “human” and less static. Widening and narrowing the pan on accents can also highlight certain parts.

Mixing Doubling Effects

While any single doubling technique can be effective, combining methods often yields the most realistic and complex results. Blending short delays, chorusing, pitch shifting and panning together gives doubles depth.

Balancing the levels of each effect is crucial to an organic double sound. The dry track should lead, with delays/chorus/pitch shift subtler underneath. Overdone effects sound unnatural and distracting. Taking time to blend levels, EQ and compress each layer thoughtfully is key.

Automating the send levels to the effects over time increases realism. Slowly opening and closing the amounts of delay, modulation and panning makes the double track sound more dynamically performed. Matching effect changes to the musical phrasing improves doubling.

Using a console’s send/return paths enables optimal blending and movement. Sending the lead vocal to parallel delays and choruses makes balancing and automation easier than inserting effects directly. This workflow provides lots of flexibility.

Crafting distinct chains for each doubling method avoids muddiness. For example, compressing/EQing the delayed layer uniquely from the pitch shifted layer keeps each doubling dimension clear.

Thoughtful multi-effect processing elevates simple doubles into engulfing three-dimensional textures. Carefully mixed parallel effects chains surrounding the dry track take doubling possibilities far beyond just copying a track. Used artfully, these techniques create natural layered depth and space.

Doubling Vocals

Doubling is commonly used on lead and backing vocal tracks to create a bigger, richer sound. There are effective strategies for doubling both main vocals and harmonies.

On lead vocals, short delays in the 30-50ms range often work well. This subtly thickens the main vocal without audible separation. Chorus and gentle pitch modulation also blend nicely for transparent doubling. Playing with panning can provide width, but keeping the lead vocal centered is common.

Backing vocals lend themselves naturally to doubling. Panning backing harmonies opposite each other creates nice width and separation from the lead. Tight chorusing brings out the harmonic content. Delay and pitch fluctuation evoke a group feel.

Using reverb on vocal doubles helps meld them with the lead vocal. As vocals are dry by nature, a touch of shared reverb creates cohesion. Too much reverb, however, can push doubles too far back. A moderate room or plate reverb suits most doubles.

EQing doubles differently than the lead vocal clarifies the blend. Boosting air frequencies on doubles adds top-end sparkle, while cutting competing midrange frequencies prevents muddiness. Compression can also refine the blend and balance.

Doubling Guitars

Guitar parts, both rhythmic and lead, are prime candidates for doubling in productions. Doubling adds thickness and dimension to acoustic and electric guitar tracks.

For rhythm guitar parts, doubling acoustics with electrics is common. The brighter attack of the acoustic will cut through clearly, while the electric fills out the sustain. Short, dark delays on the electric guitar thicken up the rhythmic bed.

Lead guitar fills and solos benefit from brief delays to widen and strengthen lines. Pitch shifted harmonizers also lend a nice layer of sustain and harmonic complexity. Chorus provides fluidity and thickness.

Quad-tracking guitars with multiples takes is commonplace for huge wall-of-sound tones. Hard panning two doubles opposite the original guitar parts creates gigantic stereo spread. Slight performance variations and blending add organic feel.

When doubling guitars, be careful of honky mids building up. EQ’ing each part differently and high-passing doubles avoids low-mid muddiness. Using DRI or mute automation can clarify the arrangement.

In rock, pop, and blues, doubled guitars provide punch, power and fullness. From doubletracking acoustic strumming to blowing up electrics with octave effects, doubling is essential to the classic guitar sound.

Doubling Other Instruments

Beyond vocals and guitars, doubling techniques can enrich a wide variety of instruments in the mix. Doubling bass, keys, drums and other parts adds depth and spaciousness.

For bass, octave effects, chorus and distortion all thicken the low end nicely. Blending the direct bass subtly with an octave down fattens the foundation. Chorus brings out the harmonics adding fullness. Mild distortion spreads the soundstage.

Doubling piano parts relies more on stereo imaging, pitch and EQ techniques. Widening the piano using short delays panned left/right makes it enveloping. Subtle pitch wavering sounds strikingly realistic on piano. Brightening the EQ of doubled keys keeps them defined.

Drums can be doubled through parallel compression and extra room mics. Squashing and blending cymbal bus channels provides shimmer and sustain. Blending in distant room mics creates natural roominess. Sample layering also effectively doubles drums.

Approaching doubling of less common instruments creatively expands their potential. There are no hard rules. The same techniques that work on standard instruments can enhance the dimension of any part, when applied tastefully.

Doubling in Different Genres

While doubling concepts remain similar across genres, specific techniques and applications vary based on the style. Understanding genre conventions helps shape doubles appropriately.

In rock, heavier doubling on guitars and vocals helps create a dense, powerful sound. Short delays and chorusing thicken guitar parts. Doubling vocals with tight harmonies reinforces melodies. Doubling is integral to the rock aesthetic.

Pop doubling tends to be more selective and spacious. Vocals and leads are doubled minimally for warmth and polish. Panning creates width on backing parts. Too much doubling can overstuff the bright pop mix.

Electronic music relies more on creative effects like phasers and flangers to double. Synthesizers and vocals sound fantastic treated with movement and modulation. Creative delays embellish drum patterns. The sky’s the limit.

Knowing when not to double instruments prevents muddiness. Acoustic instruments already rich in harmonics may not need doubling. Panning elements apart and clearing the arrangement’s center also avoids buildup.

Examining uses of doubling in specific productions provides edification. From Queen’s multitracked harmonies to Daft Punk’s robotic vocals effects, iconic albums contain doubling gems to inspire new ideas.

Effective doubling aligns with the genre’s overall aesthetic. Rather than defaulting to stock techniques, custom-tailoring doubles based on the style yields optimal musicality.

Doubling vs. Imperfect Doubling

Doubling has the reputation of making tracks sound “thicker”, but it’s a fine line between effective doubling and overcrowded “mud.” Understanding the pros and cons of precision doubling helps avoid muddiness.

Exact doubling with flawlessly copied tracks has benefits. Aligned phase coherence maximizes loudness. Perfectly cloned tracks interlock seamlessly in the mix. This precision results in clean, unified doubling.

However, too-perfect doubling risks sounding sterile and robotic. Small imperfections add organic variability, the way no two vocal takes will ever be identical. Subtle differences in timing, pitch, tone, and expression humanize doubled tracks.

Misconceptions around doubling causing “mud” stem from poor execution, not imperfection. In fact, imprecise doubling has natural Masking and can fill space without clutter. True muddiness results from overlapping frequencies and excessive layering.

The “sweet spot” lies between perfection and imperfection. Thoughtful blending of dry and processed tracks creates natural fullness. Minor random modulations bring motion and life. A balanced approach leads to doubles with satisfying depth and organic feel.

With practice and critical listening, doubling can thicken mixes without muddiness. Rather than chasing flawless duplication, embrace the variability that makes music human. A pinch of imperfection gives doubles color.

Doubling in a Digital Audio Workstation

While analog gear was once required, today’s DAWs offer accessible integrated doubling tools. Understanding DAW workflows and settings for doubling enables efficient production and mixdown.

Creating send/return effects racks with delays, chorus, and modulators streamlines doubling signal flows. Sending tracks to these racks allows for easy level and effect balancing. Quickly duplicating tracks is another fast way to double parts.

To reduce latency and strain on the CPU, bouncing doubles to audio is advised. Freezing or flattening dense doubled parts saves processing power for mixing. This avoids artifacts and lag.

Mixing doubles ITB provides convenience but lacks the analog “sweetening” of a console. Using modeled analog effects and gentle console emulation plug-ins helps compensate. Automating channel strips per part retains clarity.

Reference professional doubles on studio monitors, headphones and consumer systems. Pay special attention to the mono compatibility and phase coherence of dense mixes. Cleaning up masking frequencies and competition prevents mud.

With care taken to minimize artifacts and ensure clarity, today’s DAWs handle doubling efficiently. A thoughtful workflow allows for sculpting doubles that sound convincingly natural and impactful.

When to Avoid Doubling

While doubling can be powerful, it isn’t always the right choice. Overusing doubling or applying it poorly risks muddiness, masked elements, and clutter. Knowing when to avoid doubling keeps mixes clear.

Doubling in the wrong frequency range can make instruments mask each other. Doubling bass in upper mids would mask guitars and keys. Doubling vocals below 150Hz would compete with bass. Doubling smartly in complementary frequency zones prevents this.

Some instruments provide their own natural doubling effect. Pianos, distorted guitars and synth pads already contain dense harmonics and chorus-like qualities. Doubling them can easily sound overdone. Let the instrument’s innate richness shine.

Picky doubling of only certain words or notes draws too much attention. Doubling should elevate the entire line or phrase naturally, not spotlight single elements jarringly. Subtlety is key.

Dense arrangements can easily become overcrowded. If every element is already full-spectrum and rich, exercise restraint when doubling. Clever panning and selective doubling avoids mushiness.

Trust your ears – if a double is making the mix less clear, undo it. Clarity and musicality should drive doubling choices, not a desire to blindly thicken every track. Sometimes solid singles say more than muddled doubles.

Final Thoughts

When done with care and artfulness, doubling takes mixes to a richer, more compelling level. There is both science and craft to excellent doubling. Understanding psychoacoustic principles provides a foundation. Choosing the right techniques and aptly applying them makes the difference.

Delays, chorus, pitch shifting and panning each offer their own colors for doubling. Used singly or in combination, these effects emulate the natural variations in multiple performances. Tasteful processing elicits realism. Moderation prevents artificiality.

Doubling production and mixing techniques continue to evolve. Examining innovative uses of doubling in modern music pushes the craft forward. Emerging tools enable new flavors of enhancement. As technology progresses, so do the dimensions doubling can bring.

In the end, the art is in the ear of the engineer. Thoughtfully doubling instruments and vocals requires critical listening skills. Being judicious separates enhancement from muddiness. Developing an aesthetic sense for elegant doubling ultimately determines success. With practice comes mastery of this nuanced studio craft.

For those looking to hone their doubling prowess further, many online resources exist. From in-depth doubling tutorials to producer interviews, a treasure trove of knowledge awaits. The journey never ends for the committed professional.