Ampeg B-1 / B-1R preset

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

The Ampeg B-1 and B-1R are early-1990s 350-watt hybrid bass heads. The input, with a 15 dB pad, feeds a valve preamp of two dual triodes with Gain, Low, Mid and High controls, Shift switches on mid and treble, and Ultra Low and Ultra High switches. A switchable Solo section with Voice and Boost uses optocouplers, an optical limiter guards the output, and a DI with pre/post switch and Master feed a bipolar transistor power amp.

• Made in: USA
• Wattage: 350W
• Channels: 1
• Preamp tubes: 12AX7

Tags: american, bass, hybrid, 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.