What tubes does the Ampeg B-12XT & B-18X - Channel One use?

The Ampeg B-12XT & B-18X - Channel One uses 3× 12AX7 preamp tubes and 2× 6L6 power tubes.

When was the Ampeg B-12XT & B-18X - Channel One produced?

The Ampeg B-12XT & B-18X - Channel One was produced 1963–1968.

Ampeg B-12XT & B-18X - Channel One preset

Close · 77/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The B-12XT and B-18X Channel One schematic documents the standard input path of these extended-treble PortaFlex bass combos. Both models share the same circuit, differing only in speaker size. The XT/X extended treble response adds articulation and note definition to the classic warm PortaFlex bass tone.

Years produced: 1963–1968
Made in: USA
Wattage: 22W
Channels: 2
Preamp tubes: 3× 12AX7
Power tubes: 2× 6L6

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