Marshall JCM800 Bass Schematics
With the JCM800 Bass range of amps Marshall specifically wanted to get a foot into the Bass amp market. This line of amps and cabinets was soon to be revamped into the IBS range.
JCM800 1986 Bass, 50W head
The design of the JCM800 1986 and 1992 amps departed from the “classic” Marshall Bass amp design and incorporated a better tone stack with a mid sweep and a slope control not found on the older JMP 1986 and JMP 1992 amps.
Schematic with 3x ECC83 & 2x KT77/EL34 (2x 6550 US), (Marshall, 1981).
JCM800 1992 Bass, 100W head
The design of the JCM800 1986 and 1992 amps departed from the “classic” Marshall Bass amp design and incorporated a better tone stack with a mid sweep and a slope control not found on the older JMP 1986 and JMP 1992 amps.
Schematic with 3x ECC83 & 4x KT77/EL34 (4x 6550 US), (Marshall, 1981).
JCM800 5501 Bass 12, 12W 1×10″ bass combo
This solid state bass combo was in production from 1984 upto 1991.
JCM800 5502 Bass 20, 20W 1×10″ bass combo
This solid state bass combo was in production from 1984 upto 1991.
Schematic, Issue 2 (Marshall, 1986).
JCM800 5503 Bass, 30W 1×12″ bass combo
This solid state bass combo was in production from 1981 upto 1991.
Schematic, Issue 5 (Marshall, 1990).
JCM800 5506 Bass 60, 60W 1×15″ bass combo
This solid state bass combo was in production from 1984 upto 1993.
Schematic, Issue 5 (Marshall, 1988).
JCM800 5520 Bass, 160W 1×15″ bass combo
This solid state bass combo was in production from 1983 upto 1988. The schematics date from 1982 however. It was fitted with a 15″ Celestion G15Z-200 T3629 8Ω 200W speaker.
Schematic of the pre amp, Issue 1 (Marshall, 1982).
Schematic of the power amp, Issue 1 (Marshall, 1982).
Photograph of a 5520 Bass combo. Thanx to Jelle Falk.
JCM800 1934, Bass 1×15″ 150W 8Ω cabinet.
These cabinets were in production from 1983 up to 1986. It fitted with a “specially made Celestion” 15″ 8Ω 150W speaker. This cabinet was primarily meant as an extension cabinet for the 5520 Bass combo.
JCM800 1935A, Bass 4×12″ 260W/280W 16Ω angled front cabinet.
These cabinets were in production from 1980 up to 1986. They were fitted at first with four 12″ Celestion G12-65 T3101 16Ω speakers and later (1983 onwards) with four Marshall Celestion 12″ 16Ω speakers.
JCM800 1935B, Bass 4×12″ 260W/280W 16Ω angled front cabinet.
These cabinets were in production from 1980 up to 1986. They were fitted at first with four 12″ Celestion G12-65 T3101 16Ω speakers and later (1983 onwards) with four Marshall Celestion 12″ 16Ω speakers.
JCM800 1937, Bass 2×12″ 130W/140W 8Ω extension cabinet
These extension cabinets were in production from 1981 up to 1986. They were fitted with two 12″ Celestion G12-65 T3101 15Ω speakers. In (probably) 1983 the switch was made to two Marshall Celestion 12″ 70W 16Ω speakers.
JCM800 1981A, Bass 2×15″ 200W angled front cabinet.
These cabinets were fitted with two “Celestion-Marshall” 15″ 100W speakers.
JCM800 1981B, Bass 2×15″ 200W straight front cabinet.
These cabinets were fitted with two “Celestion-Marshall” 15″ 100W speakers.
JCM800 1984A, Bass 4×12″ 320W/400W 16Ω angled front cabinet.
This special “heavy duty” cabinet was originally fitted with four 80W 12″ speakers but later this was changed to four 100W 12″ speakers.
