The 1231 graphic equalizer provides standard features like dual 31-channel 1/3 octave bands, ISO frequency centers, +/-12dB input gain range and switchable 40Hz/18dB per octave low-cut filters, but also includes other thoughtful features. These include 45mm faders, selectable +/-6dB or +/-15dB boost/cut range for precise gain adjustments, XLR, barrier strip and 1/4'' TRS connectors for installation ease, balanced inputs and outputs for quiet operation, and chassis/signal ground lift capabilities for quick hum isolation. The visionary design of the dbx 12 series makes your job easier. The 12 series equalizers were precision engineered to provide years of maintenance-free operation in any application. The magnetically isolated transformer, electronically balanced/unbalanced inputs and servo balanced/unbalanced outputs, RF-filtered inputs and outputs, and power-off hard-wire relay bypass with 2 second power up delay were steps our engineers took to ensure compatibility for all installations. Only the best components were utilized, yielding a 10Hz to 50kHz frequency response, greater than 90dB SNR (ref +4dBu), less than 0.005% THD +Noise (1kHz at +4dBu), and interchannel crosstalk of less than -80dB from 20Hz to 20kHz. All this attention to detail is contained in a 2U steel/aluminum chassis.