intermodulation distortions with the technology of the 1930s. According to the additional patents and the reviews at that time, its later design finally implemented, seems to had shifted to the sound-colorization system using the combinations of set of free reeds, microphones and loudspeakers. Note that, similar type of instruments using the pairs of free reed and microphone sealed in the double-soundproof boxes, were later re-commercialized as Croda Organ in 1959 by Tōyō Denshi Gakki Kenkyūjo (In English: Tōyō Electronic Musical Instrument Laboratory) in Tokyo. Electronic organs The most models and years of introductions are based on official chronicle. Also, the photograph of major models on each era is available on the 50th anniversary site. Prototype Electone E-T (1958, prototype concept model) ET-5 (May 1959, Improved version of E-T Prototype) EM-6 (May 1959, Single-stage keyboard prototype) 1st Electone D-1 (1959–1962, electronic organ products) Stage models EX-21 (1968, prototype of EX-42) EX-42 (1970–1977, stage model, design origin of GX-1) SY-1 (1971, solo part of GX-1, monophonic synth with initial/after touch) SY-2 (1971) GX-1 (1973 to 1982, polyphonic synth) EX-1 / EX-2 (1977–1983) FX-1 (1983–1988, FM synthesis) HX System1 (1987–1992) HX-1 / HX-1S (1987/1989, AWM(PCM)+FM) ELX-1 / ELX-1m (1992/2000) Number series 305 / 315 (1979, export model) 405 / 415 (1980, U.S. models of the D-65 / D-85) 6000 (1981, export model) 7000 (1982, export model) A series A-2 (1960–1963) A-3 (1966, red combo organ, forerunner of YC series) A-40 / A-60 (1977, export model) A-45 / A-55 (1978, export model) A-505 (1982, export model) AR series AR-80 (1997, export model) AR-100 (1996, export model) B series B-1 (1961–1962) B-3 (1964–1965) B-5 (1965–1969) B-6 (1966, export model) B-7 / B-7D (1967, export model) B-2 / B-6B (1968–1971) B-6E / B-12 / B-12R (1970, export model) B-2B / B-4 / B-5A / B-6D / B-10A (1971–1973...1978(B-4)) B-4B / B-5BR / B-6ER / B10AR / B-20R (1971, export model) B-4C / B-4CR / B-10BR / B-30R (1972, export model) B-6R / B-10R (1972–1974/1975) B-5CR (1973, export model) B-2R (1974, export model) B-11 / B-20 / B-30 / B-30T / B-50 / B-50T (1974–1975...1978(B-30)) B-20CR / B-30AR / B-40R / B-50R (1976, export model) B-40 / B-45 / B-60 (1977, export model) B-35 / B-55 / B-75 (1978, export model) B-70 (1979–1982) B-101 / B-102 / B-103 (1982–1984) B-204 / B-405 / B-605 / B-805 (1982, export model) BK-2 (1975, export model) BK-4 / BK-7 (1973,