Ampeg Portaflex SB12 - 7868 Power tubes preset

Verified · 85/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The SB-12 Portaflex is a compact flip-top bass combo with a 12-inch speaker, offering the classic PortaFlex design in a smaller, lighter package. The Normal channel delivers warm, balanced bass tone ideal for small venues and studio recording. A practical alternative to the heavier B-15N.

• Years produced: 1962–1968
• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 3× 12AX7
• Power tubes: 2× 6L6

Tags: bass, american, vintage, low-wattage, 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.