Helmholtz Sound Synthesiser. Max Kohl. Germany, 1905

Helmholtz Sound Synthesiser
Max Kohl’s ‘Helmholtz Sound Synthesiser’ 1905. Image from Bonham’s History of Science auction
22 October 2014, New York.
Max Kohl AG founded on 14 March 1876  was a well known company that designed and built scientific mechanical and electrical instruments and was based on Andorfer Str, Chemnitz, Germany. The company created a huge range of equipment sold throughout the world to laboratories and universities including a sound instrument based on a design by the German physicist and psychologist Hermann von Helmholtz. The Max Kohl AG factory in Chemnitz was destroyed by allied bombing during WW2 and most of the remaining equipment was transported intact after the war to the Soviet Union
Helmholtz
Hermann von Helmholtz ‘On the Sensations of Tone as a Physiological Basis for the Theory of Music’ 1870. Image: openlibrary.org 2023
The ‘Sound Synthesiser’ was not intended as a musical instrument but a scientific tool to demonstrate and analyse the effect of overtones in complex sound as described in Helmholtz’s revolutionary 1870 book Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik ( ‘On the Sensations of Tone as a Physiological Basis for the Theory of Music‘ ) which had a huge impact on musicologists and instrument designers throughout the twentieth century. Using resonators, Helmholtz demonstrated the components of complex sounds are a combination of overtones of a fundamental note (e.g. a “fundamental” pitch G 440Hz contains a harmonic series of whole number multiples of this  440Hz frequency or overtones – 880Hz G , 1320Hz, 1760Hz, etc. at variable volumes). The Sound Synthesiser used a number of tuning forks – which produced almost pure tones – vibrated by electromagnets which in turn were amplified by a Helmholtz Resonator to generate overtones. The range of overtones could be ‘filtered’ by a mechanical shutter. The instrument helped in the understanding of the nature of speech and vowel sounds; vowel sounds being varied combinations of resonant overtones or ‘formants’ created by the muscles of the vocal tract.
Hermann von Helmholtz, 18953 Image: The Century gallery of one hundred portraits selected from The Century Magazine. New York : The Century Co., [1897], plate no. LXIV. Copyright 1895, by The Century Co. US Library of Congress.
Many variations of Helmholtz’s resonators were built; some were brass spheres used with hand-held tuning forks, others used electromagnets to excite the tuning forks. Max Kohl’s 1985 version had ten forks and their corresponding resonators attached to a 39½ x 29 inch mahogany base. The system is driven by an intermittent current provided by a large horizontal master tuning fork and was operated by pressing on the keys on a small ivory keyboard which sent the current to the corresponding electrically driven tuning forks. The keyboard is marked; ut [Do, or C] to 4 octaves, mi [E] to 3 octaves, and sol [G] to 3 octaves. The synthesiser was capable of combining timbres of 10 harmonics to form multiple vowel sounds.

Images of Max Kohl’s Sound Synthesiser


Sources

http://www.bonhams.com/auctions/22247/lot/245/

http://www.hps.cam.ac.uk/whipple/explore/acoustics/rudolphkoenig/koenigsanalyzer/

http://www.sil.si.edu/digitalcollections/trade-literature/scientific-instruments/files/51637/index.htm

https://archive.org/stream/onsensationston00helmgoog#page/n2/mode/2up

One thought on “Helmholtz Sound Synthesiser. Max Kohl. Germany, 1905”

  1. a question please. If a tuning fork was mounted central inside a Helmholtz resonance vessel and activated, would the vessel resonate the same as if it was outside ?

Leave a Reply

Your email address will not be published. Required fields are marked *