10 febrúar 2012
Vocal Production
Just how do you achieve that extra bit of professional polish for your vocal parts? Find out with our in-depth guide...
Any attempt to explain the process of vocal production in its entirety, with all the different genres, styles and subjective opinion that this would entail, is, to some extent, doomed to failure — there’s just no way to pack all that we have to say about this topic into a magazine article. But so critical is the role of the vocals in most contemporary music styles that we thought we should give it a go anyway — so whether you need help with arranging or performing, recording or mixing, there should be something here for everyone.
One notable contemporary production fashion is to keep vocals sounding relatively forward and free from obvious reverb without allowing them to dry out altogether, and that’s one area we’ll focus on. However, along the way we’ll be throwing in a few other tips and tricks that will allow you to add variety to the vocals in different parts of a song while still retaining the illusion of minimal processing. I can guarantee that you won’t learn everything there is to know about vocal processing, but at the same time I’m sure that you will take away something useful that can be applied in your own mixes.
The Low-down On Popping
Pretty much everyone knows that using a vocal mic up close without a separate pop screen of some kind is likely to result in audible popping on those plosive ‘B’, ‘P’ and ‘M’ sounds. What may be less obvious is that a significant amount of low-frequency energy from these sounds still makes its way through a typical pop screen, and though it’s usually too low in level to be audible, opening a spectrum analyser plug-in on your vocal track can show up considerable activity down as far as 20Hz, or even beyond. Although you may not be able to hear these low frequencies, they eat up valuable headroom and occasionally conflict with the legitimate low frequencies in your mix from other instruments.
A low-cut filter, either on the mic or on the preamp (most are 80Hz, 18dB/octave) employed at the recording stage will help, but even that may not entirely cure the problem — so additional low-cut filtering of the vocal track using a similar filter while editing or mixing may be needed to adequately suppress those unwanted lows. In most cases, you can afford to increase the low-cut filter frequency until you just start to hear it affecting the tonality of the voice, then back it off again slightly so that the filter is set as high as possible without compromising the low end of the vocal sound.
Squeeze Me
Low frequencies can still make it through a pop screen and a low-cut filter — either on the mic/preamp or during the mix, or both — will help clean things up before you start performing other processes. In this screen shot, a low-cut filter is just one part of the EQ in an instance of the SSL Vocalstrip plug-in.
Pop production makes regular use of compression on vocals, not just to even up the level but also to increase the average vocal energy, to help vocals stay on top of a busy backing mix. However, over-compressing a vocal can stifle the life out of it, so it’s often better to use level automation to fix any obvious level disparities and, where necessary, to ride the overall vocal level to suit the dynamics of the song. This leaves the compressor with less work to do, so you can adjust it to give the most artistically pleasing sound rather than having to rely on it to level the vocal unaided. A moderate ratio of between 2:1 and 4:1 with an attack in the region of 10ms and a release time of 50-100 ms usually works fine as long as you don’t apply more than 5dB or so of gain reduction on the peaks. Rock and urban music styles can usually stand rather more compression, but for a natural sound, keep the amount of moderate. After all, the overall mix is likely to be subjected to even more compression at the mastering stage, or even before then, if you’re mixing through a bus compressor.
Bear in mind that your DAW’s channel fader is usually set up so that it governs the level after any insert processors like compressors or EQs in the signal chain. If you want the level automation to affect the signal going into the compressor, you’ll need to edit the levels on the waveform, automate a gain plug-in before the compressor, or automate the compressor’s input level. Alternatively, you could place the compressor in a post-fader insert slot if your DAW allows that, or route the corrected channel to a bus, where you then add the compression. There’s nothing wrong with automating the level after the compressor, but do be aware that the two approaches will give different results, as the compressor is working on different signals in each scenario. In practice, very often you’ll end up using both tactics.
I often use parallel compression (the signal is split in two, and one treated with a compressor while the other is left untreated) on lead vocals, but the compressed signal has to be mixed in sparingly to avoid the result sounding overblown and congested. By feeding both the parallel compressor and any necessary reverb or delay effects from the vocal channel’s aux sends, it’s possible to keep the parallel compression contribution completely dry. When it’s mixed in with the channel signal and any added reverb and delay effects, this helps add weight without losing the focus of the sound. The usual rules of engagement apply when setting up the parallel compressor: use a high ratio and low threshold to achieve gain reduction values in excess of 20dB and set fairly brisk attack and release times so that gain pumping is actively encouraged. You only need add in around -20 to -15dB of parallel compression to notice the vocal gaining weight and authority.
EQ Or Multiband Compression?
Other than the low-cut filtering that I mentioned earlier, there are no golden rules as to how much EQ a vocal will need to make it sit comfortably in the mix. Much obviously depends on the character of the voice, and that of the microphone and (rather less) the mic preamp that were chosen to record it.