Marshall JMP Super Bass 1992 - High Treble preset

Verified · 87/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The 1992 Super Bass is the 100-watt bass version of the plexi-era Marshall head. Four inputs across two channels feed an ECC83 gain stage and cathode follower into the classic Marshall tone stack, with four EL34s in fixed bias. Guitarists often use it too, as its circuit sits very close to the 1959 Super Lead.

• Years produced: 1965–1981
• Made in: UK
• Wattage: 100W
• Channels: 2
• Preamp tubes: 3× ECC83
• Power tubes: 4× EL34

Known for: Jimmy Page, Lemmy Kilmister, Adam Jones.

Heard on: Achilles Last Stand — Led Zeppelin (1976); Ace of Spades — Motörhead (1980); Jambi — TOOL (2006).

Tags: british, vintage, bass, plexi, el34, high-wattage, two-channel.

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.