What tubes does the Ampeg B-12NB / B-15NB - Channel Two use?

The Ampeg B-12NB / B-15NB - Channel Two uses 3× 12AX7 preamp tubes and 2× 6L6 power tubes.

When was the Ampeg B-12NB / B-15NB - Channel Two produced?

The Ampeg B-12NB / B-15NB - Channel Two was produced 1962–1966.

Ampeg B-12NB / B-15NB - Channel Two preset

Close · 72/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The B-12NB/B-15NB Channel One schematic documents the standard input path of these NB-revision PortaFlex bass combos. The NB suffix indicates a minor circuit update to the N-series design. The warm, punchy tone of these amps was central to the bass sound of countless recordings from the mid-1960s.

Years produced: 1962–1966
Made in: USA
Wattage: 25W
Channels: 2
Preamp tubes: 3× 12AX7
Power tubes: 2× 6L6

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

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.