505 Baxandall Stereo EQ is an analog, stereo Baxandall-based equalizer for final-master sweetening. It uses sum/difference processing to preserve channel symmetry and fixed-frequency shelving for three bands: lows 100 Hz, mids 1.6 kHz, highs 10 kHz, each with ±12 dB. Width control modulates stereo image via the difference signal, from mono to expanded imaging. 20 Hz–20 kHz, transformer-balanced line input; max output +21 dBu. Stereo 500-series chassis required.