Chromotrope

From Presto-Times November 1930! Chicago's 9th annual radio show

"The Oxford Chromatrope - Frank Reichmann is the designer of the Oxford Chromatrope, a radio-phonograph combination, manufactured by the Oxford Radio Corporation, 2035 West Pershing Rd. Chicago. Mr Reichmann is chief engineer and sales manager of the Oxford concern. The Oxford Chromatrope is much more than a speaker, it is a sound machine involving many other factors found necessary for perfect sound creation. The Chromatrope incorporates all of the features of Mr. Reichmann's achievment in perfecting sound reproduction and actually introduces a new era in radio reception."

In questo link sono elencati 5 modelli, di cui 4 con immagini e 0 con schemi.
Elenco delle radio e altri apparecchi della Oxford (Tartak) Radio Corporation; Chicago