The Ampeg Bassamp Company, founded in 1949 by Everett Hull, responded to the growing demand for electric bass equipment by producing a line of bass amplifiers. The first model offered was the Super 800, an 18-watt model with a single 12" speaker and a rear ventilation port. In 1951, Ampeg introduced a 20-watt version with a 15-inch speaker. In 1960, they introduced the B-15 Portaflex, a flip-top 25-watt tube bass amplifier with a single 15" speaker. While the Portaflex had a pleasing bass tone, and was used by studio bassists such as James Jamerson and Carol Kaye, it was not powerful enough to be used in a stadium or arena concert. Ampeg amplifiers were widely used by electric bass guitarists in the 1950s and 1960s.