4 Walls

Background

South Korea-based girl group f(x) had been known as a five-member girl group, with its original lineup consisting of members Krystal, Amber, Victoria, Sulli, and Luna. The group's last release as a five-member group was Red Light, released in July 2014. During the promotion of Red Light, member Sulli did not participate in live performances due to her "suffering from continual negative comments and false rumors," according to the group's parent company S.M. Entertainment's official statement on July 25, 2014. f(x)'s promotional activities thereafter involved the four other members, while Sulli took a career hiatus. On August 7, 2015, it was announced that Sulli had officially withdrawn from the group to focus on her acting career, and f(x) would continue to promote as a four-member group.

Release and promotion

f(x) was announced to be working on its then-forthcoming studio album on September 11, 2015, when the group traveled to Jeju Island to film a music video. The album, titled 4 Walls, was released digitally worldwide on October 27, 2015 by S.M. Entertainment. In South Korea, the album was distributed digitally and physically by S.M. Entertainment and KT Music. The music video for the title track "4 Walls" was released simultaneously. The song impacted Korean Broadcasting System's "K-Pop Connection" radio on October 29.

Following the release of the album, f(x) appeared and performed on several music programs. Its first televised appearance was on October 29, 2015 on Mnet's M Countdown, where the group performed "4 Walls" and "Diamond". The group subsequently appeared on KBS' Music Bank and MBC's Show! Music Core on the two following days, respectively. To further promote the album, f(x) embarked on the concert tour Dimension 4 – Docking Station, which was its first concert tour since their debut in 2009. The tour kicked off in Seoul, South Korea at Olympic Park from January 29 to 31, 2016, and further included six shows in four cities of Japan: Tokyo, Fukuoka, Osaka and Nagoya. The tour lasted from February 20 to 28, 2016.

Musical styles

The album, in the words of Pitchfork Media, keeps up with f(x)'s signature electropop and synthpop styles that the group cultivated through its previous albums Pink Tape (2013) and Red Light (2014). Jeff Benjamin of Billboard noted the emphasis on house and dance genres on the album. The opening track "4 Walls" was described as a tropical house song with "slinky" synthesizers and "dreamy" hooks by The Star. It was characterized as an "update" of UK garage by Spin, while Billboard detailed it as having a deep house sound. The next song, "Glitter", is an R&B and synthpop number. "Deja Vu" mixes industrial beats with glitch pop sounds, while "X" draws influences from the 1980s funk, 1990s disco and R&B.

"Rude Love" is described as a piano house song with dance fusion. "Diamond" is an electropop song, while "Traveler" features retro-styled melodies and smooth rap verses. The track "Papi", instrumented by synthesizers, infuses Latin music and EDM styles. "Cash Me Out" is an EDM song that incorporates elements of American electropop. The album closer "When I'm Alone" is a synthpop track which was initially written by Canadian singer Carly Rae Jepsen during recording sessions for her third studio album Emotion (2015), but its inclusion was withdrawn and its rights were later purchased by S.M. Entertainment.

Critical reception

4 Walls was subject to favorable reviews from music critics. Jeff Benjamin from Billboard shared that despite the fact that the album was "arguably worse" than f(x)'s previous albums Pink Tape (2013) and Red Light (2014), it allowed the other members to showcase their vocal abilities more following the departure of Sulli. He praised it as a "rarity in K-pop to do once" by "finding the right sonicscapes" and appreciated the "house and trendy dance" production. Benjamin subsequently named 4 Walls the second best K-pop album of 2015, writing: "Known for crafting some of the best full-length K-pop albums, f(x) did not disappoint with their long-awaited 4 Walls comeback."

Jakob Dorof on behalf of Pitchfork Media labeled the record a "superficial rebirth" following f(x)'s lineup change and commented that the other members had the chance to express their talents more, particularly with Amber's alto "harmonies" on "Rude Love". He, upon reviewing the album for Spin, disliked the songs "Deja Vu", "Papi", "Cash Me Out" and "When I'm Alone". He nonetheless labeled them "minor misgivings" and complimented 4 Walls on featuring "sophisticated and innovative" musical styles that could "signal a surprise second life for the world's greatest living pop group." Echoing Dorof's viewpoint, Chester Chin of The Star was not impressed by the inclusion of the "derivative" tracks "Glitter" and "Cash Me Out", yet expressed his admiration for the "solid and edgy" album's "more cohesive" sound as well as "more polished and sharper" beats.

Commercial performance

4 Walls was a commercial success in South Korea, and also charted in Japan and the United States. It debuted atop South Korea's Gaon Album Chart on the chart issue dated October 25–31, 2015. It was the fourth best-selling physical album of October 2015 in South Korea, with sales figures standing at 65,933 copies. The album was additionally the eighteenth highest-selling album of November with 7,820 units sold. Overall, it ranked at number thirty-three on the Gaon's 2015 year-end album chart, with accumulated sales of 75,625 copies. 4 Walls debuted at number thirty-nine on Japan's Oricon Albums Chart on November 16, 2015. It peaked at number one on the U.S. Billboard World Albums Chart on November 14, 2015, becoming f(x)'s second number one on the chart following 2013's Pink Tape. 4 Walls was the group's best-charting album on the U.S. Heatseekers Albums Chart, where it charted at number seven. The single "4 Walls" debuted at number two on South Korea's Gaon Digital Chart for the week of October 25, 2015. It was the twenty-sixth best-selling single of October 2015 (199,976 digital units sold), and the twelfth best-selling single of November 2015 (247,232 digital units sold) in South Korea. The track debuted at number two on the U.S. Billboard World Digital Songs, becoming their highest-charting song on the chart.