Soldano SP-77 Preamp - Overdrive preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Soldano SP-77 (Series II, 1992) is a two-channel all-tube rack preamp built to feed a separate power amp. A shared 12AX7 input stage splits into a Clean channel (Volume with bright switch, one gain stage) and an Overdrive channel (Volume and two cascaded stages, one a cold-clipped stage with a switchable bypass cap). Each channel has its own cathode-follower-driven Treble, Bass and Mid stack and Master, footswitch-selected into a 12AX7 output stage. No effects loop on this drawing.

Tags: american, preamp, high-gain, two-channel.

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.