Steelphon was an Italian musical instrument manufacturer based in Turin, founded by engineer Mario Ferro. From the 1960s through the 1980s, the company built a varied catalog that included guitar amplifiers, electronic organs, analog synthesizers, effects, and a small number of guitars.

On the amplifier side, Steelphon produced models such as the Pioneer, Club, Conductor, Gloster, Kansas, Minibass, Polaris, and Texas. The Pioneer is among the most recognized of the line: a 50-watt tube combo running four EL84 power tubes, with two channels, tremolo, a Gibbs spring reverb tank driven by an ECL86, and a pair of 12-inch IREL speakers from Genoa.

Steelphon is best remembered today for its analog synthesizers, particularly the monophonic S900 and its single-oscillator sibling, the MAGO. The S900 paired two oscillators with six selectable presets and is often cited as one of the earliest synthesizers to offer programmable preset storage. Both instruments were produced in small numbers and have become collector items in the vintage Italian synth market. The S900 is notably associated with David Bowie, who used one during the Berlin-era period.

Steelphon has 2 products cataloged on Equipboard, including Combo Guitar Amplifiers and Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Rock, Pop, and Funk / Soul. Notable users include David Bowie.