Again, there are lots of guidelines about setting EQ. But don’t let this confuse you early on. Basically, this is a fancy way to change the tone of the signal. Knobs that are tied together in brackets work together. One determines the frequency range that will be affected and the other knob determines how much boost or cut will be applied to the selected frequency range. The first instinct is to turn everything up. Indeed this is quite natural but wrong. Test after test, many people will say one sound is better than the other even though the only real difference is the higher or louder volume level. If you think of boosting the frequency group with the EQ as if it were an amplifier turning the frequency group louder, this will help explain why we needed the extra head room when setting up the gain stage – you are making the signal louder when you add EQ boost. If everything is set and you boost a channel EQ, you can unintentionally overload the input level on the EX send for example, causing that signal to distort or clip when returning back to the mix.
In this configuration there is a hi frequency group cut/boost knob. Then there are hi-mid frequency knob tied to a cut/boost knob and below another pair in the Low-mid frequency range. Underneath that is the low end group cut/boost knob. In essence, select the amount of cut or boost on the frequency groups (Hi – Lo) to shape sound so it reflects the source signal.
For the paired knobs, select the frequency to be affected and using its pair cut or boost that particular frequency (as opposed to a larger group of frequencies for the Hi-LO knobs). Keeping in mind sometimes less is really more, rather than try to turn frequencies up or louder to make them sound better, try making them sound bad. Which frequencies interfere with the shape and tone of the instrument? Does a certain frequency make a nasty squawking sound when it is a bit louder? Try cutting that frequency a good amount. You might be able to turn the channel volume up after cutting signals and keep the level not necessarily louder over-all in the mix but in the correct group or place in the instrument/vocal mix. Listeners will be able to hear the instrument clearer and more distinctly if it closely resembles the real instrument’s group. So this gets pretty easy. Like a simple home stereo, turn the top know to clockwise to make the sound brighter by increasing the hi frequency group. Turn it counter-clockwise if it sounds harsh or brittle in the upper range. The paired knobs allow you to select specific frequencies within a group (Hi or Mid) and then cut or boost to shape the tone of the source and add flavor or reduce gremlins.
For microphones that will be used by vocalists, this is an area where you can make a lot of difference because the vocalist signal is also being sent to the on-stage monitors. Sometimes they are really loud. And when that happens, the monitor is blaring the vocalist’s signal right back into the microphone on stage. This in turn goes quickly to the monitor and straight at the microphone again. Soon this will turn into a squeal in the range that is strongest or loudest. This is the classic example of a ‘feed-back loop‘.
The knee-jerk reaction is to turn the channel volume down or turn the monitor sends down. The better way is to learn which frequency/frequency group is triggering the loop first. Use the paired EQ knobs to change the hi-mid or lo-mid frequency responsible for triggering the nasty loop. Successfully done, slowly turn the volume up a bit. Slowly increase volume (usually to the monitors, but will apply to the House Mains in some situations) until you start to hear a feed-back loop starting. Determine which frequency it is and turn it down in the mix. You want as much clear gain as you can to the performers. If you can only turn Monitor Send up to 5, let’s say or you get feedback, the performer might not be able to hear themselves over the amplified instruments and will be forced to scream louder and louder to get heard. If you pull down the offending frequencies you can turn the same signal to the Monitor Send to maybe 8 or so. Happy vocalist.