 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.
