I get so confused, Jeff Beck and/or Jimmy Page?
or Eric?
the authoritative answer from Allmusic:
Song Review by Bruce Eder
"Heart Full of Soul" was the Yardbirds' fourth single and their immediate follow-up to their first hit, "For Your Love," but it was much more than that — it was the song that introduced the group's real sound, or something close to it, to the mass public, and also helped mark the opening of a new, experimental era in British rock. The song came from the pen of Graham Gouldman, a composer/performer (later with 10CC) who had also written "For Your Love." That earlier song, although it had been a hit, didn't really represent the group's sound; indeed, it had played a key role in the exit of lead guitarist Eric Clapton, who couldn't abide "For Your Love"'s pop music attributes, especially the use of the reverb-laden harpsichord as the lead instrument. The group's recording of "Heart Full of Soul," by contrast, was very representative of the Yardbirds' music and was a production that all members of the group pursued with interest and enthusiasm. Indeed, where Eric Clapton had been dealt out of "For Your Love," his successor, Jeff Beck, played a vital role in the arrangement and recording of "Heart Full of Soul." It had been the idea of the group's manager, Giorgio Gomelsky, to use a sitar as the lead instrument on the song — this notion got as far as a rehearsal and an attempt at a recording at Advision Studios in March of 1965, but the Indian musician brought to the session couldn't play in time with the group. It was Jeff Beck who saved the song and the session with his fuzztone guitar licks, which mimicked the sound of a sitar. With rhythm guitarist Chris Dreja playing a metal-strung acoustic guitar, the effect was a startling breakthrough on a pop single for the period. The song expanded the range of guitar sounds that the public knew and understood, in much the same manner as the Rolling Stones' "Satisfaction," except that "Heart Full of Soul" was recorded first, two months earlier, and released before the Stones' recording was made. And where the latter song used the fuzztone guitar to imitate a Stax Records-style horn section, "Heart Full of Soul" reached outside of Western music altogether, imitating the sound of a Hindustani instrument. The song was not only a major hit (and, finally, one that matched the group's real sound) but an immensely influential record, inspiring hundreds of bands to try and imitate Beck's guitar and a significant number of those to look beyond Western music for their inspiration on songs. Along with the Beatles' "I Feel Fine" and the Stones' "Satisfaction," "Heart Full of Soul" heralded in a new phase of exoticism in popular music, letting the "genie" of musical experimentation out of its bottle and starting a process that would completely alter the shape of popular music, starting branches of psychedelic and progressive rock, in both of which the Yardbirds would participate fully. Strangely enough, after "I'm a Man," "Heart Full of Soul" remained in the group's repertory longer than almost any other song, right until the final tour with Jimmy Page on the eve of the group's transformation into Led Zeppelin.
