Leslie 257 preset

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

The Leslie 257 amplifier drives a Leslie organ speaker cabinet. It is an organ amp, not a guitar amp. A 12AU7A phase inverter drives a pair of 6550 tubes, with an OC3 voltage regulator, transistor relay switching and a bass/treble crossover. Its circuit is closely related to the amp in the Leslie 147.

• Made in: USA
• Channels: 1
• Preamp tubes: 1× 12AU7A
• Power tubes: 2× 6550

Tags: american, vintage, 6550, 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.