SMF, short for Sonic Machine Factory, was a boutique guitar amplifier company founded by Mark Sampson and Rick Hamel. Sampson is best known as the designer behind the Class A tube amplifiers from Matchless and Bad Cat, while Hamel built a reputation for Class A tube circuitry work and the SIB line of tube effects pedals. The pair launched SMF with the goal of building hand-wired-quality amps at a price point that sat between full hand-wired boutique builds and mass-produced circuit-board amps.

The company is best remembered for its "Watter" series of Class A tube amplifiers, beginning with the 15 Watter and extending up through models like the 35 Watter. Build details that recurred across the lineup included point-to-point hand wiring, all-steel chassis, 11-ply Birch cabinets, and military-spec components. SMF wound down operations in 2005, leaving a relatively small number of amplifiers in circulation that have since become collector items in the boutique tube amp market.

SMF has 2 products cataloged on Equipboard, including Combo Guitar Amplifiers and Guitar Amplifier Heads. Their gear is featured by 2 artists, with the strongest followings in Rock. Notable users include Greg Ginn and James McGaw.