Using EQ to Clean and Enrich Rap Vocals
Rap vocals are both dynamic and 'busy' and that can cause problems when working with tempo subdivisions as most rap vocals need micro editing to control sibilance and plosives and they are invariably locked into a tight tempo. With mid tempo laid back vocals it is far easier to locate troublesome frequencies and treat them. When vocals are condensed into a short time frame then you have to have detailed editing software to capture and treat narrow frequency ranges.
The first step in treating vocals is to use corrective processing to remove noise. Quite often, and particularly with rap vocal recordings, there is background noise picked up by the microphone. This could take the shape of headphone spill (the mic picks up the sound from the headphones), room noise (bumping into the mic stand etc) or low level broadband noise. Removing all of these various types of 'noise' is critical if you then want to use dynamic processing on the vocal take.
Once we have removed the noise we need to continue with corrective processes to remove both the nasty frequencies that reside in the vocal recording and redundant frequencies that we do not need or even hear.
One of the most important processes in music production is that of using corrective equalisation to remove redundant and problematic frequencies from audio prior to mixing. We refer to this process as cleaning.
Filter circuits (such as low-pass filters, high-pass filters, band-pass filters, and band-reject filters) shape the frequency content of signals by allowing only certain frequencies to pass through. We are going to look at a filter circuit that uses both a high pass and low pass filters. The two together form what we in the industry term as a band-pass filter.
The type of equaliser filter I use for all cleaning tasks is a band-pass filter.
So, why band-pass? Because what we are trying to achieve is to remove low end frequencies that are not needed and high end frequencies that are also not needed (which many seem to ignore). These are called redundant frequencies. The frequencies we keep are the frequencies we are going to process.
Now that we have removed all redundant frequencies we can concentrate on colouring the 'good' frequencies that are left but first we need to locate these frequencies which we term as target frequencies.
I don't think I have ever come across recorded vocals that do not exhibit a modicum of boxiness. You can hear boxiness straight away - it sounds like the vocals have been recorded in a cardboard box. Depending on the gender of the vocal take boxiness can sit anywhere from 200 Hz to 600 Hz and even these figures are arbitrary. When treating boxiness we use a parametric equaliser as that topology has variable bandwidths (Q factor) and can boost and cut at any frequency. However, the hard part is to locate the correct frequency to treat. We call the selected frequency the Target Frequency and this is the frequency where we place the filter's cut-off.
The hardest part of using equalisation is to find the exact frequency you want to process. There are processes in place that make this task easy to execute and one excellent trick is to use the band solo feature on the equaliser. Some well designed eqs will afford the user the ability to solo any eq node/band so that the specified frequency range can be heard in isolation. This is an extremely helpful aid and a technique I always use when it comes to using eq.
Topics covered in this video are:
Nodes and Bandwidth
Brickwall and Peaking
Q and Resonance
Understanding the Response
Tips and Tricks