The instrument
The M-100 is a further development of the M-3 (1955-1964). The M-3, also known as the Baby-B3, is a spinet model with two manuals of 44 keys and a 12-note bass pedal. The M-100 also has presets, reverb, additional switches for the chorus effects and a 13-note bass pedal. The built-in amplifier drives two loudspeakers, while a third loudspeaker is used for the reverb effects.
The Spinet organs like the M-100 and the L-100 are smaller than the classic B-3 model. There are related to the B3, but have shorter keyboards, built-in amplifiers, and fewer pedal options. These compact organs are more portable, and were used by many musical groups, due to their lighter weight and transportability for touring.
Details
Electrical impulses of various frequencies are produced within a tone generator, containing a number of tone wheels driven at predetermined speeds by a synchronous motor and gear arrangement. Each phonic wheel is similar to a gear, with high and low teeth. As the wheel rotates these teeth pass near a permanent magnet, and the resulting variations in the magnetic field induce a voltage in a coil wound on the magnet. This small voltage, when suitably filtered, produces one note of the musical scale, its pitch or frequency depending on the number of teeth passing the magnet each second. A note of the organ, played on either manual or the pedal keyboard, generally consists of a fundamental pitch and a number of harmonics of the fundamental frequency. The notes available on each key are individually controllable by means of drawbars and preset keys.
The signals passes through the expression control and through the preamplifier, where vibrato is introduced, to the power amplifier and the self-contained speakers. Reverberation is added electrically by a second amplifier which drives a reverberation speaker, also located in the console.