Gibson GA-20 Year1954-1957 ModelGA-20Watts16Speakers1x12"CabinetComboNotesTwo preamp tubes, two 12AY7, one 12AX7. Output tubes, two 6V6, cathode-bias. Rectifier, 5Y3. Speaker, Jensen Special Design P12R. Folders Amp Archives Gibson GA-20GA-20 1954-1957 7Images Leave a Comment Cancel replyYou must be logged in to post a comment.