A wonderful cloth bound manual. For the infamous Fisher K-10 spring, tele tube powered reverb. Used not only in hifi. Found employed in Hammond's finest organs. More importantly the K10 made history with the Musitron early tube synth organ. The Musitron's reverb can be heard in "Runaway" by Del Shannon. Older reprint. Approx 10 pgs with full schematics! Large A4 paper.