equalizer

7-band Graphic Equalizer with 15dB of Boost/Cut, LED indicator, and Noise-free On/Off Switch
  Behringer BEQ700 Bass Graphic Equalizer Guitar Effects Pedal (BEQ-700 / BEQ 700)

Covering the audio spectrum from 50Hz to 10kHz, the Behringer Bass Graphic Equalizer BEQ700 gives you 7 frequency bands that have been carefully chosen to give you extensive tone-shaping

31-band Stereo Graphic Equalizer with Feedback Detection System
  Behringer FBQ3102HD 31-band Stereo Graphic Equalizer (FBQ-3102HD / FBQ 3102HD)

The Behringer Ultragraph Pro FBQ3102HD 31-band graphic equalizer is packed with the professional features you need. An FBQ Feedback Detection system quickly locates problem frequencies.

Behringer Ultragraph Pro FBQ1502HD 15-band Stereo Graphic EQ with FBQ Feedback Detection (FBQ-1502HD / FBQ 1502HD)

The Behringer Ultragraph Pro FBQ1502HD 15-band graphic equalizer is loaded with the professional features you need for dialing in great live sound.