Hagstrom 840 - Channel 3 preset

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

The Typ 840 is a Hagstrom valve amplifier from Alvdalen, Sweden, drawn in 1963. Kanal 1 runs two EF86 pentode stages into a tone network, Kanal 2 uses an ECC83 and Kanal 3 another ECC83, which also drives a tremolo with a foot-pedal jack; each channel has its own level and can be switched to send/return echo jacks. A third EF86 and an ECC83 inverter drive a push-pull pair of EL34s with feedback, on silicon rectifiers, with 8 to 64-ohm outputs.

• Made in: Sweden
• Channels: 3
• Preamp tubes: 3× EF86, 3× ECC83
• Power tubes: 2× EL34

Tags: swedish, multi-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.