Bogen CHA-20 Carolina Blues Special preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The 'Carolina Blues Special' is a Bogen CHA-20 chassis rebuilt as a guitar amp. Both halves of the first 12AX7 run in parallel at the input with a Fat/Full cathode switch, then volume, treble and bass, a further gain stage and a cathodyne phase inverter. A second 12AX7 drives and recovers a spring reverb with level. Two cathode-biased 6V6s have a pentode/triode switch and master volume, on a 6AX5 rectifier with choke.

• Made in: USA
• Wattage: 14W
• Channels: 1
• Preamp tubes: 3× 12AX7
• Power tubes: 2× 6V6

Tags: american, 6v6, reverb, diy, low-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.