Ampeg SVT Preamp Rev B - Channel Two preset

Verified · 87/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The SVT Preamp Rev B documents an early factory revision of the SVT's input and tone-shaping section. Channel One feeds through the six-stage 12AX7 preamp chain. Rev B updates reflect Ampeg's ongoing refinements to the SVT circuit during the early years of production, optimizing gain staging and reducing noise.

• Years produced: 1969–present
• Made in: USA
• Channels: 2
• Preamp tubes: 6× 12AX7

Known for: Paul McCartney, Geddy Lee, John Entwistle, Lemmy Kilmister, Geezer Butler, Cliff Burton.

Tags: bass, american, vintage, high-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.