What tubes does the Ampeg B-12NF / B-15NF Portaflex use?

The Ampeg B-12NF / B-15NF Portaflex uses 3× 6SL7 preamp tubes and 2× 6L6GC power tubes.

When was the Ampeg B-12NF / B-15NF Portaflex produced?

The Ampeg B-12NF / B-15NF Portaflex was produced 1965–1967.

Ampeg B-12NF / B-15NF Portaflex preset

Verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg B-12-NF and B-15-NF are one Portaflex flip-top bass circuit in 12-inch and 15-inch speaker versions. This revision moves the 6L6GC output pair to fixed bias from a diode bias supply. Two channels of 6SL7 preamp with volume, bass and treble feed a 6SL7 inverter, with a 5AR4 rectifier. It gives the classic warm, woolly Portaflex bass voice.

Years produced: 1965–1967
Made in: USA
Wattage: 30W
Channels: 2
Preamp tubes: 3× 6SL7
Power tubes: 2× 6L6GC

Tags: american, vintage, bass, 6l6, 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.