The Marantz EQ 130 is an equalizer designed for enhancing audio output by allowing users to adjust frequencies to their liking. The EQ 130 features a 7-band equalizer, providing control over various frequency ranges, typically including 31.5 Hz, 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 ...