In 1970s Munich, Musicland Studios, led by the producers Giorgio Moroder and Pete Bellotte, had produced a number of disco hits, including Donna Summer's 1975 single "Love to Love You Baby".[9] Summer had moved to Munich to perform in the musical Hair, and had become a successful session vocalist.[9] Moroder described her as "an incredibly talented singer, who could improvise but was also very disciplined".[9] For Summer's fifth album, I Remember Yesterday (1977), the production team wanted each track to evoke a different musical decade, such as '40s swing, '60s girl groups, and '70s funk and disco. For the final track, "I Feel Love", the team wanted to create a futuristic mood.[9] Whereas most disco recordings had been backed by orchestras,[10] the team produced "I Feel Love" with a modular Moog synthesizer borrowed from the classical composer Eberhard Schoener, aided by Schoener's assistant, Robby Wedel. Wedel demonstrated how to synchronize the elements using a click track, a feat Moroder described as "a revelation".[9] Wedel's help with the technically complex synthesizer proved essential, and Moroder described him as the "unsung hero" of the project.[9] "I Feel Love" was recorded on a 16-track tape recorder, with the various parts played on a sequencer.[11][12] As the Moog went out of tune quickly, it had to be recorded in bursts of 20 or 30 seconds before being retuned.[9] To create the hi-hat sound, the team took white noise generated by the Moog and processed it with an envelope.[13] As the Moog could not create a satisfactory kick drum sound, the kick was played on a drum kit by session drummer Keith Forsey.[9] Aside from the vocals, the kick drum is the only element of the song not played by a machine.[9] Unusually for a disco track of the era, Moroder composed the backing track and bassline before the melody. He introduced variety by altering the key at regular intervals and layering Summer's vocals.[14] Each note of the bassline is doubled by a delay effect. The unmodified bassline plays through the left channel and the slightly delayed repetition through the right, creating a flickering, strobe-like effect.[13] The lyrics were written by Bellotte.[9] Summer recorded her vocal in one take.[9] In contrast to the deeper chest voice of most disco vocals, Summer sang in head voice.[13] "I Feel Love" is in the key of C major, with electronic dance flavor, and choruses and interludes. The album version has a length of 5:53. It was extended to 8:15 for release as a 12" maxi-single,[15] and is included on the 1989 compilation The Dance Collection: A Compilation of Twelve Inch Singles. The song was edited to 3:45 on the 7" format, the fade-in opening sound reaching maximum volume sooner and fades out before the third verse and final choruses. This version has been included on a large number of greatest hits packages and other compilations issued by PolyGram, Mercury Records, Universal Music and others, such as 1994's Endless Summer: Greatest Hits and 2003's The Journey: The Very Best of Donna Summer. A new edit of 3:20 was released on Donna Summer's first compilation album On the Radio: Greatest Hits Volumes I & II. Critical reception According to the singer David Bowie, who was then recording his Berlin Trilogy, his collaborator Brian Eno "came running in" and told him he had heard "the sound of the future". According to Bowie, Eno predicted that "I Feel Love" would change the sound of club music for the next fifteen years, which "was more or less right".[16] Robert Moog, the creator of the Moog synthesizer, was critical, saying:[17] That sequencer bass that's chugging along through the whole thing has a certain energy to it but also a certain sterility because it's always the same ... Warm, lyrical vocals but essentially it sounded like [Summer] was fighting the sequencer. When the sequencer stopped, I felt that I could hear the audience sort of coming alive and breathing a sigh of relief ... When [the song] is played live, what does [the band] do? The audience expects a musician to be doing something and if he's not doing as much as they expect, it's more showbiz than music. The music critic Vince Aletti wrote that "the pace is fierce and utterly gripping with the synthesizer effects particularly aggressive and emotionally charged". He predicted that the track "should easily equal if not surpass" the success of "Love to Love You Baby" in the clubs.[18]