Marshall Unicord Model 1967 Circa1970 preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Marshall Major was a 200W amplifier produced in the late 1960s and early 1970s, using four KT88 output tubes to deliver extreme headroom for stadium-level touring. Its massive power and clean headroom made it popular with bass players and high-volume guitarists before it was discontinued.

• Years produced: 1967–1974
• Made in: UK
• Wattage: 200W
• Channels: 2
• Preamp tubes: 4× ECC83
• Power tubes: 4× KT88

Tags: british, vintage, high-power, 200w.

Schematic-derived preset files for 16 Fractal and Line 6 modelers: Axe-Fx II/XL/XL+, Axe-Fx III, FM3, FM9, and the full Helix family (Floor, LT, Rack, HX Stomp, HX Stomp XL, Native).

Gridleak extracts amp parameters from original circuit schematics using AI vision — component values, gain staging, tone stack topology, tube types — then generates native preset files for every supported modeler. Every extraction is scored 0–100 and the score is published.