Marshall JCM900 SL-X 2100 preset

Verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The JCM900 2100 is the 100-watt single-channel high-gain head of the JCM900 line. The first version (Hi Gain Master Volume) used diode clipping; the SL-X shown here replaced the diodes with a third cascaded ECC83 stage before the treble, middle and bass stack. An effects loop, record and direct outputs and two footswitchable master volumes for lead and rhythm follow, and an ECC83 inverter drives four EL34s or 5881s depending on market.

• Made in: UK
• Wattage: 100W
• Channels: 1
• Preamp tubes: 4× ECC83
• Power tubes: 4× EL34

Tags: british, high-gain, crunch, el34, high-wattage.

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.