Ampeg B-15N Portaflex (1968) - Channel 2 preset

Verified · 93/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The 1968 Ampeg B-15N is a late version of the Portaflex flip-top bass combo. Each of its two channels has Bright and Normal inputs, a 6SL7 with its own Volume, Ultra Hi and Ultra Low switches, and its own Bass and Treble. A 6SL7GT long-tail phase inverter drives a fixed-bias pair of 6L6GCs with feedback from the 16-ohm tap, off a 5AR4 rectifier with standby, and there are extension speaker and external amp jacks.

• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 2× 6SL7, 1× 6SL7GT
• Power tubes: 2× 6L6GC

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.