"This combination of the Radiola 28 and the Radiola Loudspeaker 104 thus made available for the first time a complete batteryless radio receiver that could be operated like any other electrical appliance, merely by 'plugging it in.' The enthusiastic acceptance of this offering - even at the 1926 price of $250 for the 104 alone - indicated clearly that this was indeed what the public had been waiting for. This was also added fuel for the fires already lit under the development of new types of amplifier tubes especially adapted for a.c. operation, and the stampede toward their universal use in radio receivers gathered momentum quickly during 1926-1928. With the completion of the changeover to a.c. operation, the whole radio industry experienced the same kind of explosive release that follows removal of the key log in a jam, and into discard along with headphones and batteries went the last barrier between radio reception and a mass market that was soon demanding electro-acoustic transducers by the millions." (Hunt p. 81)

Sources:

• Hunt, Frederick V. Electroacoustics: the analysis of transduction, and its historical background. New York: American Institute of Physics for the Acoustical Society of America, 1982.
• Rice, Chester W. and Edward W. Kellogg, "Notes on the Development of a New Type of Hornless Loudspeaker," Transactions of the American Institute of Electrical Engineers 44, 1925, p. 461-475.

1926 RCA Radiola 100A from Radiola Guy

1928 Radiola 60 with 103 speaker, from Radiola Guy

1928 Radiola103 speaker, from Radiola Guy

1929 Radiola 33 with 100B speaker, from Radiola Guy