Vintage PA, Guitar and Audio Amplifier Schematics We carry schematic diagrams / service information for vintage PA (public address), guitar and bass amplifiers and tube powered audio amplifiers. Key companies profiled in this report are Land Instruments International (Uk), Advanced Energy. (Germany),, Lumasense Technologies (Us), Optris (Germany), Aoip (France), Optron (Germany),Bartec (Ge. Find helpful customer reviews and review ratings for TwinStar White 6" iOptron Computerized GPS Reflector Telescope at….