Ampeg SVT (1972, 6550A) - Channel 2 preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The 1972 SVT fitted with 6550A output tubes represents the peak of the original SVT's development. Channel 1 delivers the full brute force of Ampeg's 300W bass colossus, with a three-band EQ and ultra-high, high, and low input sensitivity options. The 6550A tubes run hot and hard, producing the characteristic SVT compression and warmth at high volumes.

• Years produced: 1969–present
• Made in: USA
• Wattage: 300W
• Channels: 2
• Preamp tubes: 6× 12AX7, 2× 12AU7
• Power tubes: 6× 6550

Known for: Paul McCartney, Geddy Lee, John Entwistle, Lemmy Kilmister, Geezer Butler, Cliff Burton.

Heard on: Tom Sawyer — Rush (1981); Ace of Spades — Motörhead (1980).

Tags: bass, american, vintage, high-wattage, clean.

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.