 Another factor in the Mellotron 's sound is that the individual notes were recorded in isolation . For a musician accustomed to playing in an orchestral setting , this was unusual , and meant that they had nothing against which to intonate . Noted cellist Reginald Kirby refused to downtune his cello to cover the lower range of the Mellotron , and so the bottom notes are actually performed on a double bass . According to Mellotron author Nick Awde , one note of the string sounds contains the sound of a chair being scraped in the background . 
