Dumont 3" resonoscope, developmental model: Museum Object and Cultural History

The object in the museum catalogue

Dumont X-474. Based upon a patent of Lester B. Holmes, this instrument was designed to provide a visual method for tuning a musical instrument. A specially designed cathode ray tube oscillograph is employed with twelve electrically-driven tuning forks based upon the standard tempered chromatic scale. (A = 440 cps.) The tuning forks are used to synchronize an oscillator that in turn provides the horizontal sweep circuit for the CRT. A voltage amplifier is used to pick up music or any single musical tone by use of a crystal microphone and the output of this amplifier is fed to the vertical plates of the CRT. This gives a visual picture of note wave forms under observation. If the musical note is of the same pitch as the predetermined tuning forks standard, the wave form will appear to stand still on the CRT screen. The wave form will appear to move left if the note is flat and move right if the note is sharp. A musician can thus tune their instrument by an accurate visual method. Sweep circuit employs a type 885 sawtooth oscillator. The CRT is a 3" Dumont 34-XH. References: Dumont Oscillographic - April 1937; US Patent 2153800.

Materials, dates and provenance

• date made: ca 1936
• maker: DuMont Company
• Object Name: resonoscope
• Object Name: resonoscope, dumont, sn x-474
• Object Name: musical instrument tuner
• Measurements: overall: 12 in x 7 in x 13 in; 30.48 cm x 17.78 cm x 33.02 cm
• ID Number: EM.327749
• catalog number: 327749
• accession number: 270106
• maker number: X474
• patent number: 2153800
• Credit Line: from Ethel DuMont
• Data Source: National Museum of American History

Sources and reuse

Catalogue descriptions and facts adapted from National Museum of American History through the Smithsonian's official Open Access dataset. This record explicitly marks its metadata CC0 1.0; formatting and selection have been changed.