EQ Magazine - February 2009 - (Page 38)

VOCAL CORDS COMPRESSING VOCALS by Jonathan Stars My first ex-wife hated it whenever I bought any musical equipment, because that meant she wouldn’t be able to spend the money on herself. Never mind that I was going to be a famous recording artist some day, and share all the loot with her. (Ha! I guess I showed her!) One time I bought a limiter/compressor (L/C), recorded my vocal through it, and played her the result. When she said it was the best piece of equipment I ever bought, I knew I was really onto something. Honestly, that’s how much difference it made to my recordings—and how much it can make to yours. Fortunately L/C plug-ins come with most recording software, and they’re really not that hard to use. TECHNICALLY SPEAKING A compressor controls a signal’s volume automatically by lowering the level on peaks, and raising the level during quiet parts. This produces a smaller level change at the output for a given level change at the input. For example, if increasing the input level by 4dB yields an output level change of 2dB, the compressor is said to have a 2:1 compression ratio. With vocals, compression not only brings level variations under control but brings up softer elements of the voice that add “character.” (Compression is also used with instruments like guitar and bass to add sustain, or drums to tame peaks.) Another advantage is that if the singer can maintain the same distance from the mic, an L/C can help keep the same intimacy during the entire performance because the tone doesn’t change due to the proximity effect. But a compressor can also be very helpful in the opposite situation: a singer who can’t perform without leaping all over the place. You can level out the performance, even though the tone may change. Limiting is a variation on compression that’s designed more to clamp peaks to a certain level, but leave signals under that level alone. Limiters typically use a fast attack time (under 10ms, but often less), a high compression ratio (around 20:1 or even 100:1), and a high threshold (the level where limiting kicks in). Now that I’ve started tossing around terminology, let’s look at the controls and what they do. Most of these devices come with a batch of presets to suit most common needs; Figure 1 shows the list of the Dyn3 presets that come with Digidesign’s Pro Tools. A WHISPER AND A SHOUT The human voice has a wide dynamic range, from a whisper to a shout. Because of that variation, it can be difficult to get a vocal to sit nicely in the mix where you can hear all the lyrics. A compressor is often a big help. Generally you want to set up dynamics control so you don’t notice it’s there, but plenty of engineers like to use compression as a special effect where it actually is noticeable. For example, the only way you can get that in-your-face effect used for the vocals in a lot of headbanger music is with a compressor (think AC/DC). The graph in Figure 2 on page 40 really helps to see how the controls affect the signal. The line begins moving upward at 90 degrees from left to right in a one-to-one relationship: When the input signal increases by one decibel, the output also increases by one decibel. That’s what we hear in real life. After the signal exceeds the threshold or knee (indicated by the vertical red line), the compressor attenuates (reduces) Fig. 1. The Pro Tools Dyn3 Compressor/Limiter preset list. the signal based on the ratio you select. When using the Vocal Levelor preset with a 3:1 setting, for every 3dB the input signal increases above the threshold, the output increases by only 1dB. GETTIN’ ALL SQUISHY By setting a low threshold (–30dB), compression kicks in at a correspondingly low volume, reducing high levels and raising lows. But now, we’re no longer taking advantage of the available headroom because of the reduced levels for the peaks. So, we boost the plugin’s output gain so that the peaks once again hit 0 at the output; the overall average level is now much higher. To give you some idea of how compression affects the audio, take a look at the waveforms in Figure 3. This is before raising the compressed signal’s gain so that its peak levels match the uncompressed version. On the downside, a low threshold setting also makes background 38 EQ FEBRUARY 2009 www.eqmag.com http://www.eqmag.com

Table of Contents Feed for the Digital Edition of EQ Magazine - February 2009

EQ Magazine - February 2009 Contents Talk Box Sounding Board Dave Cooley Low vs. Diamond Hank Williams III Travis Franz Ferdinand Guitar Trax Bass Management Key Issues Drum Heads Vocal Cords Mix Bus Cheat Sheet Apple Logic Pro 8 Cakewalk Sonar Near-Field Monitor Roundup Gadgets &�Goodies Sounds Room with a Vu

EQ Magazine - February 2009

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.