Ampeg A-15 / B-15 (1960) - Channel 1 preset

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

The June 1960 Ampeg A-15 and B-15 are first-generation Portaflex-era Ampeg combos. Ch. 1 and Ch. 2 inputs, plus a stereo jack, each feed half a 6SL7 with its own Volume, and the channels mix into a second 6SL7 stage ahead of shared Bass and Treble controls. A 6SL7 phase inverter drives a cathode-biased pair of 6L6GTs with negative feedback from the 16-ohm tap, and a 5U4GB rectifier with standby switch powers the amp, for roughly 25 watts.

• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 3× 6SL7
• Power tubes: 2× 6L6GT

Tags: american, vintage, bass, 6l6, two-channel, 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.