Hagstrom 620 - Channel I preset

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

The Hagstrom 620 is a Swedish two-channel valve amplifier from a 1960s factory drawing. Kanal II runs two inputs into an EF86 pentode and a tone network; Kanal I has its own inputs into half an ECC83, and the other half runs a phase-shift tremolo with a footswitch. A second EF86 adds gain and an ECC83 long-tail inverter drives a cathode-biased push-pull pair of EL86 output tubes, on solid-state rectifiers, with 32, 16 and 8-ohm speaker taps.

• Made in: Sweden
• Channels: 2
• Preamp tubes: 2× EF86, 2× ECC83
• Power tubes: 2× EL86

Tags: swedish, vintage, two-channel.

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.