Pioneer Audiovisual - The Pioneer SG-90 equalizer from 1983 had many control knobs to calibrate frequences in accordance with the room. Our current AV receivers with MCACC already know how to do
Pioneer SG-90 Equalizer.
Pioneer SG-77 Graphic Equalizers
stereonomono - Hi Fi Compendium: Pioneer SG-90
Pioneer SG-90 silver face equalizer pending sale For Sale - Canuck Audio Mart
Used Pioneer SG-90 Voicing equalizers for Sale | HifiShark.com