The Fender Bassman is considered the most important amplifier in music history. Originally designed for the Fender Precision electric bass, guitarists discovered that its power and frequency response made it the ultimate guitar amplifier. It was so revolutionary that Jim Marshall used this exact circuit as the basis for creating the iconic Marshall JTM45. It boasts a 45-watt output and four 10-inch Jensen speakers, wired in parallel within an open cabinet.