Heavy Metal music has roots tracing all the way back to 1950’s Memphis blues guitarists, who inspired or kickstarted the guitar style built on distortion-heavy riffs and power chords. Some early examples include Joe Hill Louis, Willie Johnson, and Pat Hare, the last of which created a “gritter and more ferocious electric guitar sound” on records such as James Cotton’s “Cotton Crop Blues”.
Heavy Metal’s direct origins come from the mid-1960's, with American blues music having a major influence on the British rock bands. Bands like the Rolling Stones and the Yardbirds made blues rock by doing covers of classic blues songs but often speeding up the tempos. The Kinks played a major role in popularizing the distorted guitar sound with their 1964 hit “You Really Got Me”.
The blues rock drumming style started out as simple shuffle beats on a small kit, though as time went on, drummers began becoming louder and using more complex beats to match the increasingly loud guitar. Vocalists also modified their technique in this way, using more amplification and becoming more stylized and dramatic. The Who’s “bigger-louder-wall-of-Marshall's” approach was important to the development of the later heavy metal sound.
The combination of blues rock with psychedelic rock and acid rock laid the foundation for a lot of heavy metal music. Acid rock was particularly influential in heavy metal music, as it’s often defined as a heavier, louder version of psychedelic rock. The 13th Floor Elevators were a perfect example of the acid rock sound, characterized by droning guitar riffs, amplified feedback, and distorted guitar. When rock began turning back to their blues roots in the late 1960s, acid rock bands turned into heavy metal acts.
One of the bands who contributed a lot to merging psychedelic rock and acid rock with the blues rock genre, was the British rock trio, Cream, who created a heavy sound by unison riffing between guitarist Eric Clapton, bassist Jack Bruce, and the double bass drumming of Ginger Baker. Cream’s first two LPs are regarded as essential prototypes for the heavy metal style. The Jimi Hendrix Experience’s debut album was also highly influential. Hendrix’s technical prowess influenced many metal guitarists. The album’s most successful single, “Purple Haze” is regarded as the first heavy metal hit by some. Vanilla Fudge, whose first album came out in 1967, has been called "one of the few American links between psychedelia and what soon became heavy metal”. On their self-titled debut album, Vanilla Fudge created "loud, heavy, slowed-down arrangements" of contemporary hit songs, blowing these songs up to "epic proportions" and "bathing them in a trippy, distorted haze".