Ampeg SVT Power Amplifier Section (6550A version, 1970) - Main preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

This schematic documents the 6550A power tube variant of the Ampeg SVT power amplifier, used from 1972 onward when 6146B availability declined and GE's 6550A became the preferred output tube for high-power bass amplification. The 6550A is a pentode with superior plate voltage tolerance and power handling compared to the 6L6, making it ideal for the SVT's demanding 300-watt output requirements. Six matched 6550A tubes in push-pull class AB operation remained the standard for all subsequent all-tube SVT variants through the SVT-2 Pro and SVT-CL.

• Years produced: 1972–present
• Made in: USA
• Wattage: 300W
• Power tubes: 6× 6550A

Tags: american.

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.