Dating jmp marshall amps
It was fitted with two Celestion G12L T1632 8Ω speakers. The Artiste amps were in production from 1971 up to 1978. It was an all transistor Master Volume combo amp with a reverb.The mix resistors (which mix together both channels after the first triode sections) were originally 270kΩ on the early models. In the first half of 1967 the JTM panels were dropped all together and the JMP panels were introduced. A tube rectifier was just too much hassle and too expensive. In 1965 Marshall introduced the 18W "practice" combo amps. These amps used two EL84 tubes in the power amp, three ECC83's in the pre amp and an EZ81 rectifier in the power supply. It was fitted with a reverb and a 6d B Boost foot switch. These 4140's were first fitted with two Mc Kenzie 12" 80W speakers. It was one of the first all transistor Marshall heads. This was the head version of the 2200 Master Lead Combo. Under the JCM800 "regime", the model numbering was changed.
Keep in mind that allthough I try to be complete, this is obviously not a complete list, though I hope it will be some day... The circuit was a 1959 Fender Tweed Bassman (circuit 5F6-A) clone. In the first half of 1967 the JTM panels were dropped all together and the JMP panels were introduced. In the top left corner of the cabinet a '100W' logo could be seen. In the course of 1968 the Low-High tone control circuitry was changed to a Low-Mid-High tone control and these amps were now called the Marshall Majors. The JCM800 range is split into the Lead amps (this section) the Bass amps and the solid state amps. The (Super) Leads (1959 & 1987) were issued as heads only, while the Master Volumes (2203 & 2204) and the new Split Channels (2205 & 2210) were also issued as combo's (4103, 4104, 4210, 4211 & 4212).
Desperate to build a factory large enough to meet demand, Jim Marshall made a deal with the Rose Morris company. (Thanks to Christos) This amp was in production from 1976 up to 1980. It was fitted with two Celestion G12L T1632 8Ω speakers. Special high power version of the speaker cabinets were made for these beasts. This was the accompanying cabinet for the 2001 Bass amp.
In exchange for the necessary funding (to build this new factory) Rose Morris acquired the exclusive worldwide rights to distribute Marshall amps for the next 15 years. See the Marshall Amps 2000 page for more "official" information on the 2000 amps.
Instead of fitting new EL34's, Unicord decided to fit 6550's, thinking that these "heavier" tubes would last beyond the warranty period. It used the 1987 tremolo chassis in a 4x10" combo cabinet. This is a two channel amp, one channel is that of a 1987 Lead amp and the other channel is that of a 1986 Bass amp, making it quite a versatile amp. Photograph of a JCM800 4104 (thanx to Tobbe Trygg).
This in itself was true, but many American guitar players were wandering why their Marshall amps sounded so different from their European brothers. The following three schematics are generic schematics for the 1959 & 1987 Super Lead heads, the 1986 & 1992 Super Bass heads, the 2203 & 2204 Master Volume heads and the 2103 & 2104 Master Volume combo's. See Jacques Marshall Bluesbreaker page for some nice pictures. It used the 1987 tremolo chassis in a 2x12" combo cabinet. These amps were introduced in april 1978 and were discontinued in 1982.