Ampeg V4B Power Amp - Main preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The V-4B is Ampeg's 100-watt all-tube bass head, a scaled-down SVT sharing the same tonal philosophy. The power amp section uses four 6L6 tubes in push-pull configuration, delivering rich harmonic saturation. This schematic covers the power amp stage only, but describes the full V-4B's thunderous bass amplification.

• Years produced: 1971–1979
• Made in: USA
• Wattage: 100W
• Channels: 2
• Preamp tubes: 4× 12AX7
• Power tubes: 4× 6L6

Known for: Various session bassists.

Tags: bass, 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.