Thursday, 11 July 2013

Mixing Magic Part 3


Whether you go digital or analog, the equalisation features of your mixing desk are critical to achieving a great result. Equalisation consists of different types of filters.

High Pass filters cut out bass below a certain frequency ie they let high frequencies pass through.
Low Pass filters cut out high frequenceis above a certain frequency ie they let low frequencies pass through.
EQ or Equalisation, allows the boosting or cutting of specific frequency ranges.
  • High Pass Filter - Most desks will have a Hi Pass button on them, this basically cuts out the bass below a certain locked frequency (often 100Hz). Really good desks replace the High Pass button with a sweeping high pass filter that allows you to choose the frequency of the high pass filter. This one feature is often the difference between a horrible muddy mix and a great sounding mix. I would pick a desk that had a sweeping high pass filter over a desk without it at the sacrifice of just about any other mixing desk feature. It really does make that much difference.
  • EQ - The number of bands in the EQ section are not the only thing to look out for

    • 3 Band EQ - most desks will have at least a Bass, Mid and Treble control. You simply boost or cut the knob to add or remove what you want around an arbitrary set of frequencies. This is a bit like using a "Cluster Bomb" to shoot an apple. Sure, it totally destroys the apple, but it also takes out everything else around it for miles.
    • 4 Band EQ - This splits the mid EQ into two separate knobs, one high mid and one low mid. Its better than a 3 Band EQ but is like using a cannon to shoot an apple. Again, you kill the apple but also take out things around it that you don't want to.
    • 3 Band Swept EQ - The next tier up of desks will have a sweep control on the mid section, this will appear as 4 knobs but it is still only a 3 band EQ. Don't get fooled by the middle two knobs as I have seen many people do. The bottom of the two knobs controls the frequency the Mid EQ operates at and is a different colour, the top knob controls how much that frequency is boosted or cut by. This is fantastic when you are trying to get on top of troublesome feedback. The Bass and Treble knobs are the same as the 3 Band EQ cluster bomb scenario and the two Mid controls are more like a grenade. The Apple is destroyed along with a few things around it but damage is limited to the surrounding area.
    • 4 Band Dual Sweep EQ - This adds in another band with a sweep control, so there will be 6 knobs to control the 4 bands of EQ. A high mid and a low mid gives you fine grain control over specific frequencies. This allows you to gain fairly precise control over feedback. Its like using a shotgun to shoot an apple. The apple is obliterated along with anything else right next to it.
    • Adjustable Q Control - Adjustable Q gives you additional control over the sweep control by allowing you choose a wide Q or a narrow Q. If you chose a narrow Q centered on 500Hz then it would just affect 500Hz and nothing else. As you widen the Q control then this extends the range of frequencies the sweep control affects allowing you to take out a big chunk of frequencies or narrow in on a very specific range. The Q control usually comes in the form of an outer ring knob on the sweep knob so its two knobs in one. Its the Rolls Royce of EQ and is the artillery equivalent of shooting a fruit fly on the surface of the apple with a bow and arrow.
Happy apple hunting