While graphic EQs work well for removing feedback, paragraphic EQs are often used instead. Like the parametric EQs mentioned in the sound board section, paragraphics allow the setting of the frequency to be boosted or cut. The only difference is that the control to boost or cut the signal is a slider rather than a knob. As a point of interest, the graphic portion of graphic and paragraphic equalizers comes from the fact that an idea of the signal shaping can be had by simply looking at the sliders on the front of the equipment. That is to say, it is a graphical representation of the equalization curve.
Many people often wonder how one goes about setting all of the sliders on an equalizer.
To some, it seems to be black magic, and in some ways it is. There are two main approaches to setting equalizers, and both will not always apply in a given situation. In cases where microphones are being used, there exists the potential for the system to feed back. This is a case where ringing out the system is often used. An equalizer is set up on the outputs of the sound board.