Cheat Sheet delivers concise, explicit information about specific recording/audio-related tasks or processes. This installment describes basic vocal processing.
TO POP FILTER OR NOT TO POP FILTER?
Some engineers feel pop filters detract from a vocal, but pops detract from a vocal even more. If the singer doesn’t need a pop filter, fine. Otherwise, use one.
NATURAL DYNAMICS PROCESSING
The most natural dynamics control is great mic technique—moving closer for more intimate sections, and further away when singing more forcefully. This can go a long way toward reducing the need for drastic electronic compression.
COMPRESSOR GAIN REDUCTION
When compressing vocals, pay close attention to the compressor’s gain reduction meter as this shows the amount by which the input signal level is being reduced. You generally don’t want more than 6dB of reduction. To lower the amount of gain reduction, either raise the threshold parameter, or reduce the compression ratio.
NATURAL COMPRESSION EFFECTS
Lower compression ratios (1.2:1 to 3:1) give a more natural sound than higher ones.
USE COMPRESSION TO TAME PEAKS WHILE RETAINING DYNAMICS
To clamp down on peaks while leaving the rest of the vocal dynamics intact, choose a high ratio (10:1 or greater) and a relatively high threshold (around –1 to –6dB). To compress a wider range of the vocal, use a lower ratio (e.g., 1.5 or 2:1) and a lower threshold, like –15dB.
COMPRESSOR ATTACK AND DECAY TIMES
An attack time of 0 clamps peaks instantly, producing the most drastic compression action; use this if it’s crucial that the signal not hit 0dB, yet you want high average levels. But consider using an attack time of 5–20ms to let through some peaks. The decay (release) setting is not as critical as attack; 100–250ms works well. Note: Some compressors can automatically adjust attack and decay times according to the signal passing through the system. This often gives the optimum effect, so try it first.
SOFT KNEE OR HARD KNEE?
A compressor’s knee parameter, if present, controls how rapidly the compression kicks in. With soft knee, when the input exceeds the threshold, the compression ratio is less at first, then increases up to the specified ratio as the input increases. With hard knee, once the input signal crosses the threshold, it’s subject to the full amount of compression. Use hard knee when controlling peaks is a priority, and soft knee for a less colored sound.
TOO MUCH OF A GOOD THING
Compression has other uses, like giving a vocal a more intimate feel by bringing up lower level sounds. However, be careful not to use too much compression, as excessive squeezing of dynamics can also squeeze the life out of the vocals.
NOISE GATING VOCALS
Because mics are sensitive and preamps are high-gain devices, there may be hiss or other noises when the singer isn’t singing. A noise gate can help tame this, but if the action is too abrupt the voice will sound unnatural. Use a fast attack and moderate decay (around 200ms). Also, instead of having the audio totally off when the gate is closed, try attenuating the gain by around 10dB or so instead. This will still cut most of the noise, but may sound more natural.
SHIFT PITCHES FOR RICHER VOCALS
One technique for creating thicker vocals is to double the vocal line by singing along with the original take, then mixing the doubled take at anywhere from 0 to –12dB behind the original. However, sometimes it isn’t always possible to cut a doubled line—like when you’re mixing, and the vocalist isn’t around. One workaround is to copy the original vocal, then apply a pitch shift plug-in (try a shift setting of –15 to –30 cents, with processed sound only). Mix the doubled track so it doesn’t compete with, but instead complements, the lead vocal.
FIXING A DOUBLED VOCAL
Sometimes an occasional doubled word or phrase won’t gel properly with the original take. Rather than punch a section, copy the same section from the original (non-doubled) vocal. Paste it into the doubled track about 20–30ms late compared to the original. As long as the segment is short, it will sound fine (longer segments may sound echoed; this can work, but destroys the sense of two individual parts being played).
REVERB AND VOCALS
Low reverb diffusion settings work well with vocals, as the sparser number of reflections prevents the voice from being overwhelmed by a “lush” reverb sound. 50–100ms pre-delay works well with voice, as the first part of the vocal can punch through without reverb.
A slight upper midrange EQ boost (around 3–4kHz) adds intelligibility and “snap.” Be very sparing; the ear is highly sensitive in this frequency range.
For more “animation” than a static EQ boost, copy the vocal track and run it through an envelope follower plug-in (processed sound only, bandpass mode, little resonance). Sweep this over 2.5 to 4kHz; adjust the envelope to follow the voice. Mix the envelope-followed signal way behind the main vocal track; the shifting EQ frequency highlights the upper midrange in a dynamic, changing way. Note: If the effect is obvious, it’s mixed in too high.