What tubes does the Ampeg Vt40Prea use?

The Ampeg Vt40Prea uses 4× 12AX7 preamp tubes.

When was the Ampeg Vt40Prea produced?

The Ampeg Vt40Prea was produced 1970–1978.

Ampeg Vt40Prea preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The VT40 Preamp A is an alternate schematic representation of the VT-40's input and tone-shaping section. This document may represent a specific production revision or an alternate service format used by Ampeg's service network. Used alongside other VT-40 documents for comprehensive circuit understanding.

Years produced: 1970–1978
Made in: USA
Channels: 2
Preamp tubes: 4× 12AX7

Tags: guitar, american, vintage, 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.