Marshall JCM900 SL-X 2500 preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The JCM900 2500 is the 50-watt version of the 2100 head, with the same single-channel high-gain preamp: diode clipping in the early Hi Gain Master Volume version, an extra cascaded ECC83 stage in the SL-X. Treble, middle and bass, an effects loop, record and direct outputs and two footswitchable master volumes follow. An ECC83 long-tail inverter with presence drives a pair of fixed-bias EL34s (5881s in some versions).

• Made in: UK
• Wattage: 50W
• Channels: 1
• Preamp tubes: 4× ECC83
• Power tubes: 2× EL34

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