In 1924, Hupfeld introduced its Metal Pneumatic System as a major innovation in the design of pneumatic player mechanisms. One of the principal advantages of this system was that each individual metal pneumatic unit, corresponding to a single note, could be easily removed, inspected, cleaned, reinstalled, or replaced without the need to remove the entire action or disconnect complex tubing connections. This catalog provides a detailed English-language description of the construction and operation of the system and illustrates its application in the Solo-Phonola, Duo-Phonola, and Tri-Phonola models. We offer a PDF copy of this rare 17-page catalog for research and study purposes at a price of EUR 35.00.
