FBT 250 / 250 LB preset

Verified · 89/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The FBT 250 and 250 LB are Italian tube amps from about 1972 that share a power stage: an ECC83 phase inverter driving a cathode-biased push-pull pair of EL84s into an 8-ohm speaker, with no feedback loop and a two-diode silicon rectifier. The 250 has two inputs, each with its own ECC83 triode, volume and tone, plus an ECC83 tremolo with frequency, intensity and a footswitch. The 250 LB swaps that for a single ECC83 preamp with high and low inputs and bass, treble and volume.

• Made in: Italy
• Wattage: 15W
• Channels: 1
• Preamp tubes: 3× ECC83
• Power tubes: 2× EL84

Tags: italian, vintage, el84, tremolo, clean.

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.