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[[File:Hammond_c3_Emilio_Muñoz.jpg|thumb|A Hammond model C3]] |
[[File:Hammond_c3_Emilio_Muñoz.jpg|thumb|A Hammond model C3]] |
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− | An electronic organ, designed in the 1930s, that uses a unique [[electromechanically produced music|electromechanical]] sound synthesis method |
+ | An electronic organ, designed in the 1930s, that uses a unique [[electromechanically produced music|electromechanical]] sound synthesis method. To produce the tones, classic Hammond models use a “tonewheel” system.A tonewheel is a metal plate, cut into the shape of a polyhedron or a mechanical gear, and rotating on a shaft. A magnetic pickup is mounted near the edge of the rotating plate, and the plate induces a waveform in the pickup as the bumps and variations of the plate pass by. The tonewheels are all mounted on a common shaft which is driven by a rather peculiar motor arrangement; most have to be “started” in a manner rather like starting a car engine. The keyboard is wired to a complex matrix of switches that selects the proper wheels for each key. The running motor is synchronized to the incoming power line frequency, which provides for stable tuning, but also necessitates having different versions for North American (60 Hz) and European (50 Hz) power. |
The Hammond organ can be thought of as a primitive [[additive synthesis]] machine. Sounds are made of a mix of a [[fundamental]] frequency plus [[harmonic]]s up to the 9th harmonic, plus the second and third [[Subharmonic|subharmonics]] (signals that are 1/2 and 1/3 the frequency of the fundemental). On most Hammonds sounds can be created with a set of “drawbars”, which are simply slider-type controls that are mounted so that they pull out or push into a panel, rather than sliding back and forth across the panel like conventional slider knobs. Each drawbar controls the level of one individual harmonic. A typical Hammond model has about 90 tonewheels from which all of the harmonics for any given note can be formed. (However, the lowest and highest notes don’t always have all of their tones; sometimes a tone an octave lower or higher is used for some of the harmonics of the highest and lowest notes. This is known as “foldback”, and it is part of the Hammond sound.) |
The Hammond organ can be thought of as a primitive [[additive synthesis]] machine. Sounds are made of a mix of a [[fundamental]] frequency plus [[harmonic]]s up to the 9th harmonic, plus the second and third [[Subharmonic|subharmonics]] (signals that are 1/2 and 1/3 the frequency of the fundemental). On most Hammonds sounds can be created with a set of “drawbars”, which are simply slider-type controls that are mounted so that they pull out or push into a panel, rather than sliding back and forth across the panel like conventional slider knobs. Each drawbar controls the level of one individual harmonic. A typical Hammond model has about 90 tonewheels from which all of the harmonics for any given note can be formed. (However, the lowest and highest notes don’t always have all of their tones; sometimes a tone an octave lower or higher is used for some of the harmonics of the highest and lowest notes. This is known as “foldback”, and it is part of the Hammond sound.) |