Ampeg B-18N Portaflex - Channel 2 preset

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

The Ampeg B-18N Portaflex was the largest of the classic Portaflex flip-top combos, pairing the standard 30-watt 6L6 circuit with an 18-inch speaker for maximum low-end extension and depth. While the B-15N became the more ubiquitous studio standard, the B-18N appealed to players who needed the last word in low-frequency authority. Its warm, deep, and expansive bass tone made it a favorite for upright bass players doubling on electric, and for electric bassists who wanted maximum bottom.

Tags: american, vintage, 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.