Masco MAP-18 preset

Verified · 94/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The MAP-18 (Sams 1949) is an AC-powered musical-instrument amplifier with three identical inputs. Each input has its own 6SF5 triode and volume control, mixing into a 6SJ7 pentode, bass and treble controls and a 6SL7GT paraphase stage driving two 6L6Gs from a 5V4G rectifier. Masco (Mark Simpson Manufacturing Co.) built PA and instrument amplifiers in New York, and many are now converted for guitar.

• Made in: USA
• Wattage: 18W
• Channels: 1
• Preamp tubes: 3× 6SF5, 1× 6SJ7, 1× 6SL7GT
• Power tubes: 2× 6L6G

Tags: american, vintage, 6l6, low-wattage.

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.