The book is an attempt to revive the interest of radio amateurs in tube amplifiers of sound frequency at a new qualitative level. Today, in the West and especially in the United States, interest in such ultrasound has increased unusually, as evidenced by the results of the latest developments in this area. The book contains practical descriptions of several tube ultrasound designs of varying degrees of complexity, gives practical advice of both circuit and structural nature. The second edition was published in 2000 for trained radio amateurs.