Ampeg B-12N / B-15N Portaflex (1962) - Channel 1 preset

Verified · 91/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The 1962 Ampeg B-12-N/B-15-N is the classic Portaflex flip-top bass combo, with the head mounted upside down inside the speaker cabinet. Each channel has 6SL7 stages with a Baxandall-style bass/treble network, and a 6SL7 paraphase inverter drives a cathode-biased pair of 6L6GCs for about 25 watts.

• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 3× 6SL7
• Power tubes: 2× 6L6GC

Known for: James Jamerson, Duck Dunn, Chuck Rainey, Marcus Miller, Tony Levin.

Heard on: (Just Like) Starting Over — John Lennon (1980); Never Too Much — Luther Vandross (1981).

Tags: american, vintage, bass, 6l6, two-channel, mid-wattage.

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.