A speaker cabinet that is completely open at the rear. So-called because it is formed by folding over the sides of an open baffle. See Horn, Folded.
"I want you to know I am so very pleased with the CD I received today. To hear my sister's singing voice after many years was wonderful. I know it had to be a very difficult job as the home recordings made in 1947 I sent were in such bad shape. We couldn't even hear them anymore on a 78 record player. She is in very ill health and I called her ..."