Ampeg J-12R (Diamond Blue) preset

Verified · 87/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg J-12R Diamond Blue is a compact tube guitar combo from around 2000. Guitar and accordion inputs feed a dual-triode preamp with two gain stages around passive bass and treble controls and a volume, then a long-tail phase inverter driving a cathode-biased pair of EL84s into an 8-ohm speaker. Spring reverb is driven and recovered by a TL072 op-amp, with its own level control.

• Made in: USA
• Wattage: 18W
• Channels: 1
• Power tubes: 2× EL84

Tags: american, el84, reverb.

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.