Tech 21 is a New York based manufacturer of guitar and bass effect pedals, amps, and DI boxes which allow the user to emulate the tone of many popular guitar amps and record those sounds directly into a mixer.
Tech 21's core product, the SansAmp, was designed by Andrew Barta and introduced in 1989. Although other companies have manufactured multi-effect units, the SansAmp was unique in that it introduced the concept of amp-modeling, that is, altering guitar sound to emulate different amplifiers, and allowed recording direct to a mixing console.
Other Tech 21 products have included distortion pedals (Tech 21 XXL, American Woman, etc.) and bass specific pedals, rack mount units (RBI preamp for bass, PSA-1 preamp for guitar) as well as a range of amplifiers (Trademark 30,60,120 combos Landmark heads) that use SansAmp technology built in.
While being the precursor to digital amp modeling technology, Tech 21 has continued to use only analog technology, rather than digital signal processing, as the driving force behind its tones.