Sorry for the JT link, poaltube wouldn't work. Initial sessions for the album were held in early 1969 with producer Tony Clarke, most famous for his work with the Moody Blues. After these sessions failed to work out, the group were given permission to produce the album themselves. The album was recorded on a 1" 8-channel recorder at Wessex Sound Studios in London, engineered by Robin Thompson and assisted by Tony Page. In order to achieve the characteristic lush, orchestral sounds on the album, Ian McDonald spent many hours overdubbing layers of Mellotron and various woodwind and reed instruments. In some cases, the band went through 5 tape generations to attain deeply layered, segued tracks. Some time after the album had been completed, however, it was discovered that the stereo master recorder used during the mixdown stage of the album had incorrectly-aligned recording heads. This misalignment resulted in a loss of high frequencies and introduced some unwanted distortion. This is evident in certain parts of the album, particularly on "21st Century Schizoid Man". Consequently, while preparing the first American release for Atlantic Records, a special copy was made from the original 2-track stereo master in an attempt to correct some of these anomalies. (The analog tape copying process usually results in generation loss.) From 1969 to 2003, this second-generation "corrected" copy was the source used in the dubbing of the various sub-masters used for vinyl, cassette and CD releases over the years. The original, "first-generation" stereo masters, however, had been filed away soon after the original 1969 mixdown sessions. These tapes were considered lost until 2003.