Ampeg SVT-300 preset

Verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg SVT-300 is a 300-watt tube bass power amp from 1991, built to be driven by a separate preamp through its main and aux inputs. A 12AX7 cathode-coupled phase inverter with a balance trim feeds two 12AU7 drivers, each with its own bias control, which drive six 6550s in push-pull into an output transformer with an impedance switch. The volume and presence controls are wired off this board.

• Made in: USA
• Wattage: 300W
• Channels: 1
• Preamp tubes: 1× 12AX7, 2× 12AU7
• Power tubes: 6× 6550

Tags: american, bass, 6550, power-amp, high-wattage.

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.