Mesa Boogie Bass 400 - Channel 2 preset
Verified · 82/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.
The Bass 400 is Mesa/Boogie's original all-valve bass head, built from 1985 until the Bass 400+ replaced it in 1989. Two inputs, each with its own volume and bright switch, feed a bass, middle and treble stack with bass and treble shift switches, a six-band graphic EQ, a blendable effects loop and a master. A 12AX7 long-tail driver and cathode-follower buffers drive six fixed-bias 6550s (or 6L6s), with a slave output, for clean, deep headroom.
- Years produced: 1985–1989
- Made in: USA
- Wattage: 400W
- Channels: 2
- Preamp tubes: 4× 12AX7A
- Power tubes: 6× 6550
Tags: american, bass, 6l6, 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.