This little book was a large feature in the corruption of my life when I was 15 or so. Technology useful to the Mayans, since they didn't have transistors yet, and I'll assume they were restricted to whatever a quad of pentodes could deliver in class AB. Tons 'O fun. Mr. Bose ruined all of that with his 901, which would absorb 100 watts just to be audible, but still sounded great, and took up hardly any space.