 Their production also emphasized instrumentation and was a departure for Ocean after Nostalgia , Ultra 's reliance on samples . In the studio , they reworked the musical ideas from their writing sessions , incorporated live production , and ornamented their songs musically . Ocean enlisted Los Angeles @-@ based producer Om 'mas Keith to help him rework the songs . They added live drums to " Crack Rock " , " Monks " , and " Sweet Life " , which was originally produced as a digital track . Originally written by Ocean for singer Bridget Kelly , " Thinkin Bout You " had been recorded as an early take by him and posted on his Tumblr account in July . Ocean and Malay 's final mix of the song for the album added a strings intro . For " Bad Religion " , engineer Jeff Ellis tried to compensate for the few string players they had by arranging seating for a large string section in EastWest 's Studio 1 and using a pair of old stereo ribbon microphones to capture the sound . They sat players in different seats each time they played along with the track in order to mix all of the takes together and give the impression of a larger ensemble . 
