Marshall B150 preset

Verified · 84/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The B150 is a mid-1990s 150-watt hybrid bass combo. Passive and active inputs feed an op-amp gain stage with compression, then a single ECC83 valve stage whose dirty signal is mixed with the clean path by a Blend control, with Deep and Bright switches and Treble and Bass. A seven-band graphic EQ (40 Hz to 8 kHz), switchable limiter, effects loop, line out and XLR DI with earth lift follow, into a discrete transistor power amp.

• Made in: UK
• Wattage: 150W
• Channels: 1
• Preamp tubes: 1× ECC83

Tags: british, bass, hybrid, 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.