What tubes does the Harmony H-311 use?

The Harmony H-311 uses 12AX7 preamp tubes and 6L6 power tubes.

When was the Harmony H-311 produced?

The Harmony H-311 was produced 1964–1969.

Harmony H-311 preset

Verified · 85/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Harmony H311 is a companion to or successor of the H310 with slightly revised specifications or cosmetic details. It delivers a similar warm, clean push-pull tone to the H310 with simple tremolo and basic channel switching. The H311 is typical of Harmony's mid-to-upper student and semi-professional amplifier range from the mid-1960s.

Years produced: 1964–1969
Made in: USA
Wattage: 18W
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.