Fender Rumble Bass - Channel A preset

Verified · 89/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Rumble Bass is Fender's 1990s all-tube bass head, not the later solid-state Rumble combos. Two relay-switched channels with 12AX7 gain stages, mid-cut switches and Fender-style tone stacks can be combined, and there are two effects loops. A 12AT7 phase inverter and 12BH7 cathode-follower drivers push six fixed-bias 6550s for about 300 watts.

• Made in: USA
• Wattage: 300W
• Channels: 2
• Preamp tubes: 4× 12AX7A, 4× 12AT7, 1× 12BH7
• Power tubes: 6× 6550WA

Tags: american, bass, 6550, high-wattage, two-channel.

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.