While Calvin Harris had a pretty good career going already as a dance-pop singer and producer with two albums and a fair number of hits under his belt, his 2011 collaboration with Rihanna on “We Found Love” gave his profile a stratospheric boost. On 18 Months, so titled because that’s how long it took to be made, Harris steps away from the microphone for the most part in favor of a cast of famous friends and acquaintances to create an album that plays like 50 minutes of mainstream radio pop. The basic template of the album’s sound can be found in “We Found Love,” with its melancholy and romantic lyrics, impassioned vocal build-ups, and pounding techno beats all coated with layers of shiny synths. The success of each effort rests on the vocalist and how well they can fit their style into the Harris sound. For example, Ellie Goulding’s icy innocence on “I Need Your Love” works far better than Florence Welch’s desperate wail that pushes “Sweet Nothing” over the top. Elsewhere, Kelis’ sassy and assured work on “Bounce” is fresh and fun, and Ne-Yo’s smooth croon complements “Let’s Go” perfectly, but Example’s bland vocals add nothing to the rote “We’ll Be Coming Back,” and Tinie Tempah couldn’t have done much to save the banal party rocking anthem “Drinking from the Bottle.” Two of the lesser-known names on the record turn in the best efforts, as Harris himself helms the record’s second best track, “Feel So Close,” with distinctive style and nicely subtle emotion, and Ayah Marrar's vocals bring Harris’ best melody to life with a classy understatement. That the album‘s success is so tied to the vocalist on each track brings up the album’s main flaw, which is that apart from the handful of instrumental interludes and the not very interesting hip-hop track “Here 2 China,” every song sounds like a carbon copy of the ”We Found Love” template. This reliance on such a specific sound works better on a single by single basis -- something Harris himself seems to recognize since six of the album’s 15 tracks were released as singles prior to 18 Months' debut. Over the course of an album, it can be rather wearying and points to a lack of creative energy and an unwillingness to experiment which is very disappointing. Although 18 Months may show Harris to be a solid producer with an easily identifiable sound -- and any record that includes “We Found Love” can’t be all bad -- it’s something of a step backward in his progress as an artist.