Creative Vocal Processing
Technique : Effects / Processing
Tired of the same old vocal sound? Time to get creative with your plug-ins, FX pedals and anything else you have!
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When it comes to treating vocals, we generally think
first of compression and reverb, but there's a wealth of other vocal
treatments that may not be quite so obvious. Not all are applicable to
all styles of music, but it's still worth trying them at least once,
just so that you know what they sound like. There isn't space here to
explore every effect in detail, but you should find something to inspire
a bit of vocal creativity!
Vocal EQ has been covered in great depth in previous
articles, so I won't revisit it here. Suffice it to say that choosing a
mic type and position that gives the right sound at source is better
than using EQ to knock a disappointing recording into shape. If you need
to add an airy gloss after the fact, the merest broad boost at 12kHz
usually does the trick or, if you're lucky enough to have a TC Powercore
system, the included Character plug-in or the optional Specific Vocal Enhancer plug-in from Noveltech do the job very simply and effectively.
The first thing most engineers do to a vocal after
(or even during) recording is to add compression. As I'm sure you're
aware, compressors restrict the dynamic range of sound, making the level
more even. In a pop music context, where the backing track levels are
also tightly controlled, this can be important in getting the vocal to
'sit' correctly in the mix. Without compression, the vocal level may
drift between being too loud and too quiet. Having said all that, using
compression alone to tame level differences isn't usually the best way
forward. Some singers have great control over their dynamics, while
others will get noticeably louder when they sing in certain registers
and if you use enough compression to deal with this, the vocal can end
up sounding seriously squashed. A better approach, where available, is
to use track level-automation to iron out the most obvious excesses,
then use compression to smooth the end result. Where mix automation
isn't available (for example, with a traditional stand-alone recorder
and analogue mixer setup), you'll need to ride the faders while mixing
and apply the compression at the same time — just like the old days!
Noveltech's Specific Vocal Enhancer plug-in for the TC Powercore platform can help to bring an airy gloss to your vocals.
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The type of compressor you use also makes a
difference, because compression straddles the line between effect and
processor, in that it can alter the perceived character of the sound, as
well as control its dynamic range. All compressors increase the average
level of the sound as a direct result of bringing the level of the
quieter notes closer to the level of the louder ones. The subjective
effect, though, is also influenced by the attack and release times of
the compressor, and by the amount and type of distortion it adds. As a
very general rule, the most transparent compressors (those that reduce
the dynamic range without affecting the subjective sound too much) use
VCA gain-control elements, while those using FETs, tubes and opto
devices tend to add a little more character. Generally, a vocal
compressor needs to be set up with a fairly fast attack time (just a few
milliseconds) and with a release time in the order of a quarter to half
a second, but you can sometimes fake the more obvious aspects of an
opto compressor's character by using a long attack time and a fast
release on a compressor that is normally fairly transparent-sounding.
Of course, you need to be aware that the more
compression you use (in other words the higher the gain-reduction meter
reading), the more gain will be applied to low-level sounds relative to
high-level sounds, a consequence of which is that unwanted low-level
sounds, such as noise or the spill from headphones, will become more
obvious. Where the recording is being made in an imperfect room, the
room ambience will also become more pronounced when you add compression,
which is why it is essential to record vocals in an acoustically
treated space, even if the treatment is only a duvet behind the singer.
More aggressive compression can be used for certain
rap and 'death metal' vocal styles, and if you haven't already tried it,
it's worth downloading the free Talkback Compressor from the SSL web site (www.solid-state-logic.com).
This is available from the Resources / Downloads and Manuals section
after you've filled in a few registration details, and works as a VST or
AU plug-in on Mac or PC. It is modelled on the talkback mic compressor
used in SSL consoles, which leapt to fame when it was used to help
create the big Phil Collins compressed and gated drum sound. There are
plenty of other compressors, but this one is seriously unsubtle, and
works a treat on vocals that need more attitude!
Because the tape cumulatively colours the sound every time it repeats, tape echo units (or virtual models of them, like RE201 for the UAD1 card) can give a warmer sound than digital delays, and one that often sits better in a mix.
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Reverb is the other vocal essential, if only to
replace the natural ambience lost through recording in a dry
environment. Few small studios have the sort of natural acoustics that
suit pop vocals, so the usual approach is to use an acoustically dead
vocal booth, then add back the desired ambience during mixing using some
form of artificial reverberation. The main thing to consider here is
that what sounds like a lot of reverb when you solo the vocal may be
barely noticeable when the whole mix is playing, so always adjust the
final reverb level in context.
The choice of reverb is an artistic
decision: what sounds most natural and 'room-like' doesn't necessarily
sound the most musically pleasing. That's why algorithmic reverbs and
plates are still often used in preference to convolution reverbs, which
are based on real spaces such as concert halls. Where convolution
reverbs are used, it is often with impulse responses taken from hardware
reverb units. This makes sense when you consider that we've become so
used to the sound of electronic reverb over the past few years that we
perceive it as being artistically right. While it is difficult to
comment generally about reverb, the current trend seems to be to use
less obvious reverb treatments than in the '80s or '90s, so short,
bright plates and lively ambiences are often used in addition to, or in
place of, more conventional reverb treatments.
One vocal effect that has been used quite a lot in
recent years is the 'telephone' filter. This can be as simple as rolling
off both the low and high end, using steep filters to squeeze the audio
into a band roughly between 250Hz and 2kHz. While it would sound odd to
treat a whole vocal part this way, it can still be effective for short
passages. However, you can also achieve some interesting variations on
this effect in a very different way.
Audio Ease's Altiverb, and similar convolution plug-ins, can offer interesting and authentic variations on the 'telephone' vocal effect.
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The convolution process is best known for its
ability to capture reverbs and ambiences, but it is equally applicable
to short delays or devices that produce predominantly tonal changes.
Plug-ins such as Altiverb from Audio Ease can be used to create
this type of effect, in this case if you download additional impulse
responses from the Audio Ease web site (free to registered users). One
of these sets includes impulse responses (IRs) taken from small
transistor radios, telephones and so on. The transistor radio IR sounds
extremely convincing when used to squeeze a voice into a narrow part of
the spectrum, and because the IR is able to capture the more complex
tonal attributes of the system being measured, the result is somehow
more believable than if you used simple EQ filtering. If you don't have
Altiverb, there are alternatives, such as Logic Pro's Space Designer or the freeware, PC-only SIR, as well as online resources such as Noisevault (http://noisevault.com/nv), where you can download IRs.
If you have the tools to capture your own IRs (either built into the convolution plug-in, such as with Space Designer, or a stand-alone impulse-capture application like Fuzz Measure),
you can easily create your own effects by taking IRs from small
speakers, transistor radios and guitar practice amps. While you're at
it, you can also take IRs from toy microphones with springs inside,
cassette recorders (to give you that real squashed tape effect) and even
tape echo units, if you can get your hands on one for a couple of
hours.
Talking of tape echo units, echo has become almost
as important a vocal effect as reverb. This can vary from the very
obvious surf echo of the '60s and Pink Floyd excesses of the '70s and
'80s, to short, slapback echo as immortalised by artists from Elvis to
John Lennon. While conventional digital delays offer low-noise,
wide-bandwidth, pristine echo, they don't sound nearly as musical as
tape echo. This is because tape echo has a softer sound that gets warmer
and less distinct every time the sound is fed back and repeated, which
makes the delay sit further back in the mix, supporting the dry sound,
rather than fighting for a place at the front of the mix.
Leslie speaker emulators like Logic Pro's Rotary
are a well-known processing trick for organs and guitar sounds, but
they can also add that special something for vocals, and can even make a
vocal line sound like an instrument.
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Tape echo units are now fairly rare and quite
expensive, but fortunately there are numerous hardware and software
solutions that use programming to mimic the distortion, filtering and
pitch instabilities of tape echo. Not only is their cost a fraction of
that of their hardware counterparts, but the tape won't break during
some vital solo! You can also get impulse responses from tape echo
machines for some convolution reverbs, but because of the long delay
times involved, this can be excessively hungry on CPU resources unless
you're after a simple slapback. I'll often use a subtle repeat echo
mixed in with a reverb to fatten a vocal, but I also like that slapback
effect for certain productions where you need just a single short delay
(typically 80 to 150ms) high in the mix.
Of course if you have an open-reel tape machine
lying around that uses separate record and play heads, you can also use
this as an echo unit, simply by feeding it from the send on a mixer,
setting it to monitor the replay head, hitting record and then bringing
its output back on another spare mixer channel. If you turn up the
same-numbered send control on that channel, you'll feed some of the
tape's output back to its own input, producing repeat echoes. The fader
controls the echo level, while the send control governs the time the
repeats take to die away. The delay time and subsequent repeat time
depends on the tape speed. A speed of 15ips (inches per second) usually
gives a nice slapback effect, but if you need a longer delay, you can
patch a conventional digital delay unit before the tape machine and set
it to 100 percent wet. The tape machine will colour the sound in exactly
the same way as when used on its own, but now you have a delay time
equal to the tape delay plus the digital delay.
Another fun trick is to solo your vocal track and
then record it to a standard cassette machine. Next, record the output
of the cassette back into the computer or workstation and put it on a
new track alongside the vocal. Slide the newly recorded 'cassette track'
so that it comes just after the original dry track and you have genuine
tape delay. The timing instability of cassettes means that this may
drift out of time over long periods, but for creating slapback echo
within a typical song, it should work fine. If not, break the delay
track into sections and adjust the timing for each section. You can also
add digital delay to the tape delay track if you want to create a
repeating echo.
Used in context, more outlandish vocal effects can
be a lot of fun. Perhaps the oddest is genuine reverse reverb. We've
covered this before, so I won't dwell on it in too much detail here, but
in the good old days, you'd record a vocal, turn the tape over so that
it played backwards, add reverb and record the reverb to a spare track.
When you flip the tape back the right way around, the original vocal is
back where it should be but the reverb is now backwards and builds up
before each word in a very surreal way.
With a bit of lateral thinking you can use Logic's Platinumverb to create a John Lennon-style double-tracked vocal.
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In this DAW age, you can do much the same thing by
processing a copy of an audio track to reverse it, adding 100 percent
wet reverb, printing or bouncing the reverb to make it permanent, then
reversing the resulting reverb track before running it back alongside
the original track. You may need to adjust the timing of the reverb
track relative to the dry track for the best results. You can also do
the same thing very simply using any convolution reverb that allows you
to reverse the impulse response, by copying the audio part to a new
track, adding the reverse convolution reverb (again, 100 percent wet),
then sliding the treated track forward so that the reverb builds up just
before the start of the dry audio track.
Another favourite of mine is to pitch-shift the
audio up an octave before feeding it to a delay or reverb, a technique
that adds a surreal shimmer to the sound. I've discussed this before in
the context of guitars, but it can also be very effective on vocals.
Alternatively, if you want to be more subtle, you could try using pitch
correction on the reverb feed and adjusting the severity of the pitch
correction, so that the reverb sound is just slightly different in pitch
and character to the original. What you end up with is not quite normal
reverb and not quite artificial double-tracking but combines a bit of
both.
To force vocals to play more of a textural role in
rhythmic music, the familiar tempo-driven chopping (square-wave tremolo)
effect can produce great results cycling at eight or 16 chops to the
bar, and of course this can be used in conjunction with other effects,
to create a more complex sound. For example, adding a long, heavy reverb
and then chopping up the result can produce a sound that combines the
qualities of vocals and keyboards. Alternatively, you could chop up the
audio feeding the reverb.
I was recently experimenting with a vocal track using Logic's Platinumverb
plug-in and discovered that it can generate extremely convincing
double-tracked, slapback vocals in the style of John Lennon. You simply
set the early reflections delay time to between 70 and 110ms, reducing
the reverb time to less than half a second and then winding up the
reverb level to around 60 percent of the dry level. The settings I used
can be seen in the screenshot at the bottom of the page. Using a cluster
of early reflections to create the repeat, rather than a single delay,
makes the effect much more convincing, and if you also roll off some low
end by using a sharp filter at around 200Hz, you can get very close to
that trippy, 'Lucy In The Sky With Diamonds' sound.
Another discovery I made at the same time came about
when I was trying to dream up a way to add interest and depth to a
classic rock song, performed using just an electric guitar, an acoustic
guitar and one vocal line. I wanted the effect of a keyboard pad but
without using any extra parts, so I copied the vocal line to a new
track, inserted a long reverb of about six seconds and 100 per cent wet,
then inserted a compressor to keep the reverb level fairly high. The
final step was to drop in a stereo rotary-speaker plug-in set to its
slow speed, then mix the resulting treated reverb back under the track
so that it was only just audible. Surprisingly, the rotary speaker
effect hid the origins of the sound pretty well and the perceived result
was much more like a low-level keyboard pad than a treated vocal. This
is one I'll definitely be using again!
Of course you don't always need to come up with
original weird ideas, and there are now processors that can manipulate
the voice for you in a variety of ways. Roland's hardware VP70 Voice
Processor, for example, is great for creating quasi-robotic effects,
while companies including Antares, TC Electronic and Celemony offer
sophisticated voice-shaping processes that remodel the formant structure
of the singer's vocal tract to change the character of the voice
without making it sound too artificial. There's still plenty of scope
for going over the top if you want to create something unnaturally
growly or squeaky, but if you use such devices carefully, you can record
multiple vocal parts with one singer and then make them sound like an
ensemble of different people. In my experience, going as far as to turn a
male voice into a female voice or vice-versa rarely sounds
entirely authentic, but more subtle shifts in timbre are handled pretty
well. The same is true of automatic harmony devices as championed by TC
Helicon: as long as the harmony parts are not too complex or too forward
in the mix, they can sound very plausible, especially if you use the
randomising features that introduce human-like pitch and timing offsets
into the harmony parts. They sound even more convincing if you layer one
or two genuinely sung harmony parts over the top, just as a sampled
string patch sounds more realistic when you overdub a couple of violins.
There's such a lot you can do to process vocals in
an interesting way that it would take much more space than I have here
to explore them all. A good approach is to take processors designed for
other purposes and just try them on vocals to see what happens.
Guitar-amp simulators provide a practical way to add controlled
distortion, and rotary speakers deliver a very trippy sound, as the
Beatles discovered way back in the '60s. Distortions and overdrive
effects that you might use without thinking on guitar can create
interesting effects on a delayed vocal, particularly when combined with
other effects.
Whatever sort of music you usually make, it's always
a good idea to push outside of your comfort zone, experiment and try
something new, or try combining existing techniques in unfamiliar ways.
The resulting effect is often more than the sum of its parts and might
just give you the unique sound you've been striving for!
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