What tubes does the Harmony H-304 use?

The Harmony H-304 uses 12AX7 preamp tubes and 6V6 power tubes.

When was the Harmony H-304 produced?

The Harmony H-304 was produced 1961–1966.

Harmony H-304 preset

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

The Harmony H304 is a step up from the H303 series, offering slightly more output power and a two-channel design. The second channel typically accommodated a microphone or second instrument input, a common feature in the student combo market of the early 1960s. The tone is clean and warm with limited dynamic range and a pleasant vintage softness.

Years produced: 1961–1966
Made in: USA
Wattage: 10W
Channels: 2
Preamp tubes: 12AX7
Power tubes: 6V6

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.