What tubes does the Harmony H-400A use?

The Harmony H-400A uses 12AX7 preamp tubes and 6L6 power tubes.

When was the Harmony H-400A produced?

The Harmony H-400A was produced 1961–1966.

Harmony H-400A preset

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

The Harmony 400A is a mid-power combo from the early 1960s representing Harmony's step above entry-level, aimed at working musicians on a budget. Built in Chicago, Illinois, Harmony amplifiers used straightforward all-American tube circuits producing warm, clean tones typical of the era. The 400A was part of the company's effort to offer affordable professional-grade amplification alongside its equally affordable guitars.

Years produced: 1961–1966
Made in: USA
Wattage: 14W
Channels: 2
Preamp tubes: 12AX7
Power tubes: 6L6

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.