Nady FS-4N Feedback Suppressor Four 1/60th octave notch filters target problem frequencies between 6- to 6,000Hz. Notch depths adjust up to -20dB Spectrum analyzer LED display identifies problem frequencies Notch depths adjust up to -20dB A spectrum analyzer LED display quickly identifies problem frequencies TRS balanced connectors Includes IEC cord for AC operation and has internal power supply with voltage select switch