Marshall JCM900 Dual Reverb 4100 Power Amp/PSU (DWG 4100-60-02 Iss11) preset

Close · 72/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The JCM900 Dual Reverb was Marshall's flagship from 1990 to 1999, offering two channels with built-in reverb and a 100W EL34 power section. Though sometimes dismissed for its diode-clipped gain, it served a generation of touring rock and grunge players.

• Years produced: 1990–1999
• Made in: UK
• Wattage: 100W
• Channels: 2
• Preamp tubes: 4× ECC83
• Power tubes: 4× EL34

Known for: Kurt Cobain, Dimebag Darrell, Billy Corgan.

Heard on: Smells Like Teen Spirit — Nirvana (1991).

Tags: british, crunch, grunge, 90s.

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.