Patent GB-1048396-A (GB)
Title: Improvements in electronic musical instruments
IPC: G10H1/22
Filed: 1963-06-26
Abstract: 1,048,396. Electrophonic musical instruments. WURLITZER CO. June 26, 1963 [June 26, 1962], No. 25437/63. Heading G5J. An electronic musical instrument is provided with means which gives a preference in the sound produced to the lower or higher note of any two simultaneously played adjacent notes. The invention is particularly concerned with giving a preference to the lower of any two simultaneously played pedal notes of an electronic organ since, especially if two adjacent notes are (accidentally) played, objectionable beats between such notes are produced. Fig. 3 shows one embodiment in which the pedal switches comprising single-pole double-throw elements 38 operate to connect the four lowest frequency tone generators 34 to an output busbar 54 via resistors 52, 56, 58 and 60 of increasing values and all high in value relative to the impedance of the generators 34 so that, of these four notes, that one of lower frequency in any two played, contributes a higher output signal to bus 54 and so predominates. Subsequent groups of four pedal switches are connected to respective notes of preceding groups as shown so that the same resistors provide the required preference between notes of the subsequent groups whilst the opening of the series contacts when any note is played gives such note preference over the higher pitched note linked thereto. An advantage of this arrangement and of the embodiments to be subsequently described is that there is a smaller " build-up " of series resistance in the circuit than in known arrangements and additionally, the number of series connected switch contacts through which any note is played is also reduced over known arrangements. In a second embodiment (Fig. 4, not shown), the pedal switches 38, commencing with that corresponding to the lowest note, are connected in series in groups of four preference being given to the groups in ascending order by giving increasing values to resistors 64, 70, 72, 76, 80 and 84 whilst preference is given to the lowest note of a group played by virtue of the series connection within that group. In a further arrangement preference is given only to the lowest note the generator of which is connected directly to the output bus by the pedal switch, all other pedal switches being connected in series and all (except that for the lowest note) connecting their respective generators to the output bus via resistors of equal value to ensure that, in the event of the failure of a series switch connection all notes may still be played (Fig. 5, not shown). In another arrangement the notes, commencing with the lowest are grouped in pairs, preference being given to the lowest pair in which a note is played over all higher pairs (Fig. 6, not shown). A modification of the latter arrangement in which the notes are grouped in threes is described with reference to Figs. 7 and 8 (not shown). The arrangements of Figs. 6, 7 and 8 utilize single-pole single-throw switches instead of the double-throw switches of the earlier described arrangements. In another arrangement, also utilizing single throw switches, the notes are grouped in three's, preference being given to the lowest note of any one group, but not to any one group over the other groups (Fig. 9, not shown) and in a final arrangement the entire compass of the pedals consisting of thirteen notes (tones and semitones) are grouped in three groups of three and one group of four notes, preference being given to the lowest note of any two or more pedal switches operated (Fig. 10, not shown). In all embodiments the bus-bar signals are fed via amplifiers to sound reproduction means the various tone colours required being produced by suitable filters connected either between the tone generators and the pedal switches or incorporated in the amplifiers.