From Avedis site: 9 band Graphic EQ, -12 dB cut, +15dB boost, Unbalanced Input w/ API 2520 Opamps. Manufactered by APSI (Audio Processing Systems, Inc.) and distributed by API (then called Automated Processes Inc.). Unlike the 560, the 559 had an unbalanced input. The filter amps used IC’s, but had it’s own potted output stage discrete amplifier and an output transformer. The boost/cut sliders were actually mechanically stepped level switch with the numerical reading on the front. The bandwidth, or Q, was tighter than the 560, giving it a more “notch-ey” sound. Like all the other API eq’s, it has good noise and headroom specifications that holds well with 600 ohm loads Condition: Good for their age Price is for the pair. Screws in place to hold the front panel on, will need removing before installing in a rack. We’d suggest only installing in an API branded rack to avoid any conflict with modern rack features.
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