The BBE EQA-231 is a professional dual 31-band graphic equalizer. ideal for use in live sound rigs and installed setups such as studio, stage, DJ and sound contracting. The EQA-231 utilizes Constant-Q filters (constant bandwidth) this means that the bandwidth of each individual filter has a perfect balance between being narrow enough to prevent unwanted interaction between filters, yet wide enough to deliver exactly the type of correction curve for the ultimate in precision equalizing.