Gibson GA-5T Skylark (1961) preset

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

The 1961 GA-5T Skylark is a small Gibson practice amp with two inputs and just two controls, volume and tremolo frequency, with no tone control. Both halves of a 12AX7 provide the gain into a single-ended, cathode-biased 6BM8 pentode with negative feedback from the speaker, and the 6BM8 triode runs a phase-shift tremolo oscillator. A 5Y3GT rectifier supplies about 4 watts into one speaker.

• Made in: USA
• Wattage: 4W
• Channels: 1
• Preamp tubes: 1× 12AX7
• Power tubes: 1× 6BM8

Tags: american, vintage, tremolo, low-wattage, practice, class-a.

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.