Behringer FBQ800 Mini Graphic 9 band EQ

When a specifi c frequency, or range of frequencies, reaches too high a level, feedback occurs—that all-too-familiar squeal or howl you get when the mic is too close to the speaker. Basically, feedback happens when there is so much of a particular frequency that it is picked up by the mic and run through the system again. That’s why feedback typically gets louder and louder the longer it’s allowed to occur. Needless to say, this kind of feedback is very undesirable.