Heathkit A-7B / A-7C preset

Verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The A-7B and A-7C are early Heathkit audio amplifier kits — hi-fi amplifiers, not guitar amps. A 12J5 first stage feeds a 12SL7 amplifier and paraphase inverter driving a push-pull pair of 12A6 beam tubes for about 6 watts, with a 5Y3 rectifier; the A-7C adds an extra 12SH7/12SJ7 preamp stage. Simple octal-era circuits with a soft, clean low-power voice.

• Made in: USA
• Wattage: 6W
• Channels: 1
• Preamp tubes: 1× 12J5, 1× 12SL7 (A-7C adds 1× 12SH7/12SJ7)
• Power tubes: 2× 12A6

Tags: american, vintage, clean, low-wattage, diy.

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.