Ampeg B-4R preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg B-4R is a late-1990s solid-state rack bass head. Its op-amp preamp has gain, a five-position Style switch, Ultra Mid, a Texture switch, a 9-band graphic EQ with footswitchable bypass, a limiter, an effects loop with blend, a master, and a balanced DI with pre/post and ground-lift switches.

• Years produced: 1998–2010
• Channels: 1

Tags: american, bass, solid-state.

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.