Patent GB-403365-A (GB)
Title: Device for the production of musical sounds by electrical methods
IPC: G10H1/055
Filed: 1932-03-04
Abstract: 403,365. Electrical musical instruments. TRAUTWEIN, F., 22, Elfriedenstrasse, Zehlendorf, Berlin. March 4, 1932, No. 6586. Convention date, March 4, 1931. Addition to 380,470. [Class 88 (ii).] An instrument in which the sounds are produced by the method described and claimed in the parent Specification is operated by keys the finger parts of which are rotatable about a shaft 37, Fig. 2, against the action of a spring control. Depression of the key closes a switch, not shown, whereby the circuit of an oscillator, such as a glow discharge lamp, is completed through a resistance appropriate to the note. The finger part has a curved base on which is mounted a resistance 39 adapted to slide over a contact 40 mounted on the body of the key. The resistance 39 may be connected to the main note-determining resistance so that a vibrato or glissando effect may be produced by rocking of the finger-part. Alternatively the resistance variations may be employed to control volume or timbre variation. A resistance 42 adapted to be pressed by the finger against a contact bar 41 may be connected to an independent tonegenerator for solo playing. In the apparatus shown in Fig. 4, the contact point of the notedetermining resistance 24 is determined by depression of elastically mounted keys 21 having rounded bolsters 22 of rubber felt or the like whereby a vibrato effect may be obtained. The keys are mounted with such clearance as to permit finger-playing if desired. Keys may be provided for certain intervals only to afford guiding points. In a two-voice instrument the resistances may be mounted side by side, the keys of one alternating with those of the other. In a further modification there are no keys but a comb of insulating material with gaps shaped to the finger is mounted above the playing surface to indicate determined intervals. For example, two combs each arranged to form a whole-tone scale may be mounted one on each side and spaced apart by a semitone, the space between the two combs being free for glissando playing. Specification 339,225, [Class 88 (ii), Music &c.], is referred to. The Specification as open to inspection under Sect. 91 comprises also the following subjectmatter. (1) A keyboard instrument employing a limited number of oscillators, any key being connected to a free oscillator by means of a system of electromagnetic relays. A similar system may be employed for the distribution of timbre characteristics between the notes of a chord, and means similar to organ registers may be provided for changing the timbre-distribution when desired and for octave coupling and the like. (2) Electromagnetic actuation of sliding contacts for the automatic production of glissando. (3) Lateral adjustment of the keyboard as a whole for transposition. (4) Volume control in accordance with the pressure exerted by the keys, for example on a carbon resistance or on a variable transformer. (5) Production of echo effects by magnetic recording on a rotating or otherwise moving iron body arranged to pass beneath reproducing means after a prescribed interval. (6) The elimination of oscillating circuits from the amplifying arrangements and the use of strongly damped loud-speakers for reproduction. (7) The production of music by means of manually drawn graphical images. (8) The use of electrically maintained tuning- forks or of sirens as oscillation generators. (9) The introduction of magnesium into the glow-discharge lamps employed as oscillators. (10) The production of frequencies other than the fundamental by the frequency-changing circuit shown in Fig. 1 (Cancelled). The oscillating circuit of the fundamental note comprising a glow discharge lamp 1, variable resistance 3 and condenser 2, is connected as shown to an amplifying valve 6, the output circuit of which contains coupling transformers 11, 12 shunted by capacities 9, 10 adapted to introduce the " resonance formants " by shock excitation. The oscillating circuit is coupled by a transformer 27 to a frequency changing circuit comprising a glow discharge lamp 17, condenser 18, rectifier 15, switch 16 and output terminals 19,20. The condenser 18 may be so dimensioned that the lamp 17 ignites at every second, third &c. peak only of the applied voltage. The above subject-matter does not appear in the Specification as accepted.