1. Danger! Beware of Clipping
The most common problem I’ve encountered in rap and hip-hop recordings and mixes is clipping. If you aren’t already aware of clipping, it is distortion that occurs when signal levels are beyond the limit of a device. It seems that in pursuit of ridiculous bragging rights for the title of “Lord of Loudness,” people routinely record and mix way too hot.
What is “too hot?” I generally categorize it as any level that is so high that it causes undesired distortion. If the files you’re about to mix are already clipped, you can kiss your hopes of a clean mix goodbye. Any chance at success in significant reduction of distortion requires specialized tools such as the De-clip module in iZotope RX, which can repair clipping artifacts. Though it’s seriously amazing what can be accomplished with RX, there are limits; the core algorithms utilize technology, not miracles!
Even if your files aren’t clipping, they can still be so hot that clipping can easily occur later in the signal chain. For example, let’s say that the lead vocal peaks at -1 dBFS, and you do a 3 dB boost when EQing it. Put your math hat on: -1 dB plus 3 dB equals +2 dB. In digital audio systems, exceeding 0 dBFS will cause clipping.
There are exceptions in DAWs that have floating-point bit depth mix engines, but floating-point bit depth is outside of the scope of this article. Plus, levels over 0 dBFS in them will still cause clipping at the D/A (digital to analog) converter. So, what’s the solution?
Turn it down! Easy, right? You’ve got a shiny fader on every track precisely that purpose. Not so fast, Handsy McFaderfingers! A track’s fader typically comes after its inserts (where you insert plug-ins) in DAW signal flow. So, if clipping has occurred in a vocal track’s EQ plug-in, lowering the fader after it will only attenuate the clipped signal, not reduce the amount of distortion in the signal.
What’s better is to turn down the signal before the clipping occurs. Some DAWs such as Avid Pro Tools and Steinberg Nuendo allow you to adjust the gain of each region/clip, which occurs before the inserts. Great! If your DAW doesn’t offer such a function, you can insert a gain, trim, or EQ plug-in in the first insert slot, then lower the level in that plug-in.
Whether you lower the level at the region/clip or in the first insert slot, you’ll be giving yourself more headroom later in the signal flow, allowing you to boost levels later with a reduced threat of clipping.
2. Keep Vocals Tight
The most frequently-made mix mistake on rap vocals is applying too much reverb. Yeah, vocals drenched in reverb sound cool for ballads and ‘60s retro rock, but it’s a crying shame when rap vocals need a Coast Guard rescue to escape massive swells of reverberation. If you do use reverb on rappers, keep it subtle. Shy away from long decay times of two seconds or more and large spaces such as concert halls and cathedrals. Also, for the love of all that is remotely righteous, keep your reverb level low. Since the goal for rap vocals is typically a tight and up-front sound, use reverb sparingly.
Another factor contributing to a tight vocal sound is how layers of vocals relate to each other. It’s standard practice for rappers to record a lead vocal, a double of it, and highlights (a track in which only certain words of the original vocal are performed to highlight or emphasize them). The vocal production can get much more complex; I’ve encountered rap songs with far more vocal tracks than that.
If layered vocals are panned in the same position and have timing discrepancies beyond about 20 milliseconds of each other, the result can sound like stutters, slapback, or echo, which is distracting when the goal is clarity.
When dealing with layered vocals, a huge part of achieving a tight sound involves aligning their timing so that identical words across the layers end up in identical places. This can be done with a variety of manual editing techniques, including cut and paste, nudging, and more; however, it’s a laborious task that breeds bitterness and vaporizes your creative energy.
Time-alignment plug-ins such as Synchro Arts VocALign and Revoice Pro were designed to handle such madness and do so with time-saving ease. They can shift, stretch, and time-compress one track to match another, making them capable of manipulating the timing of a doubled vocal to match the lead vocal.
Maybe you’re thinking, “Hey dudeman, that sounds like editing, not mixing.” Yeah, you’re right! However, it is far from strange for mixing to involve some fixing, and if fixing makes the mixing better, you do the fixing!