From Wall Street Journal:
When “Whole Lotta Love” was released in October 1969, it appeared first on “Led Zeppelin II,” the band’s second album, and then as a single weeks later—with a shorter edit for AM radio. While the single reached No. 4 on Billboard’s pop chart, the album shot to No. 1 in November, and a three-month battle with the Beatles’ “Abbey Road” for the top spot ensued.
Jimmy Page: The theremin’s eerie sound begged for more experimentation. To get my guitar to sound surreal, I detuned it and pulled on the strings for a far-out effect. I was playing a Sunburst 1958 Les Paul Standard guitar I had bought from [James Gang guitarist] Joe Walsh in San Francisco when we were out there on tour. The Standard had this tonal versatility, allowing me to get a blistering high pitch.
Robert’s vocal was just as extreme. He kept gaining confidence during the session and gave it everything he had. His vocals, like my solos, were about performance. He was pushing to see what he could get out of his voice. We were performing for each other, almost competitively.
When we toured the U.S. again in May and June, we took the rough-mix tapes along with us in a large trunk. In Los Angeles, we’d work at studios like Mirror, Mystic and A&M to overdub material, and in New York we worked at Mayfair, Groove and Juggy studios. Today, digital files are emailed all over the place, but back then you had to take your tapes if you wanted to work on the road.
When we were ready to mix all the songs for the album, I wanted Eddie Kramer to do it. Eddie had engineered several of the album’s songs from scratch in London, and he had worked with us in the American studios. He also had engineered Jimi Hendrix’s albums. But by the summer Eddie had relocated to the States, so when we were in New York in August, we called him. “Whole Lotta Love” was all there on tape, but it needed a big, polished sound for the album.
Eddie Kramer: The first time I heard “Whole Lotta Love” was in August ’69, when Jimmy and I started working on the album’s final mix at New York’s A&R Sound.
Jimmy and I had first met in 1964, when he was playing on the Kinks’ first album [“Kinks”] at Pye Studios and I was the assistant engineer. I also had heard Led Zeppelin early on in ’68, when John Paul Jones had played me an acetate of Led Zeppelin’s first album, before it was released. I was blown away—it sounded so hard and heavy.
In New York, the recording console at A&R was fairly primitive. It had only 12 channels with old-fashioned rotary dials to control track levels instead of sliding faders and there were just two pan pots [control knobs] to send the sound from left to right channels. But as Jimmy and I listened to the mix, something unexpected came up.
At the point where the song breaks and Robert slowly wails, “Way down inside…wo-man…you need…love,” Jimmy and I heard this faint voice singing the lyric before Robert did on the master vocal track. Apparently Robert had done two different vocals, recording them on two different tracks. Even when I turned the volume down all the way on the track we didn’t want, his powerful voice was bleeding through the console and onto the master.
Some people today still think the faint voice was a pre-echo that we added on purpose for effect. It wasn’t—it was an accident. Once Jimmy and I realized we had to live with it on the master, I looked at Jimmy, he looked at me and we both reached for the reverb knob at the same time and cracked up laughing. Our instincts were the same—to douse the faint, intruding voice in reverb so it sounded part of the master plan.