When f(x) debuted in 2009, they didn’t immediately make headlines due to the strength of the girl groups they debuted with. They would go on to have one of the strongest discographies of their contemporaries, despite only promoting for six of those 10 years. With Amber announcing her departure from the company as her contract ends, it seems that we have reached the end of a truly experimental girl group that was ahead of their time. 

The quintet-turned-quartet grew in popularity as they established their niche identity. They weren’t girly or sensual like their peers, nor were they in your face a la 2NE1. Instead, f(x) had an experimental, quirky sound grounded in the electronic dance genre. This experimental sound would become their calling card, prominent in their Electric Shock mini album and all four albums. 4 Walls may seem very on-trend these days, but when it was released in 2015, f(x) were one of the few artists that had that specific sound. They were ahead of their time and retained their identity in every release.

This September’s Side B is dedicated to f(x) for their tenth anniversary, celebrating the quirks that make their music uniquely them. 

f(x) are known for a bratty sound that emphasizes a carefully orchestrated cacophony of electronic beats and frenetic energy, chants optional but encouraged, with sing-talking almost a surety. This is especially seen in “Toy,” and “Spit It Out,” both bearing the hallmarks of the f(x) sound.

“Toy” compares a man to a collector who treats hearts like toys that can be easily replaced. It’s more playful, with a cheer-like quality that’s played up in the pre-chorus and hook. In their sole concert tour, “Toy” was included in the setlist and used to interact with the crowd, with the pre-chorus being repeated multiple times. This is possible due to the chanting of “Put your hands up” and the like that plays into the theme of toys and going all-in on the song’s overall sound.

“Spit it Out” is the darker relative of “Toy,” as it takes the playfulness of the former and brings a musically darker subtext. It plays into the lyrics that asks the man who has played with the girls’ heart to spit it out, using the beats and silence to emphasize sections. Sing-talking is also weaponized well as precursors to the verses.

f(x) also have a variety of less busy and more musically straightforward songs. One such track is fan favorite, “Airplane.” The song captures the tension between wanting to fall in love but being afraid to fall. This is related to the feeling of being afraid to fly, and realizing the ecstasy of being up in the clouds. And yet, they still must go back down. Musically, this is reflected in the rise and fall between sections, the pre-chorus a build to the lively chorus. By the final chorus, there is a feeling of weightlessness as Luna sings, followed by being grounded back into reality as Krystal closes out the song. 

Another similar track is “Signal.” It is, as Lo put it, pure, unadulterated disco. “Signal” makes use of 70 and 80’s-esque sounds, something that would become the backbone of their fourth album. Synths are weaved in and the rhythm is kept light and flowing, not having the typical contrasting sections that f(x) songs do. There is a slight quirk in the verses that is the more upbeat sister of the languid underlying bass of “X.”  

There is also the atmospheric “Shadow” and “Butterfly,” both similar yet different. “Shadow” begins with a music box-like quality that is a sharp contrast from the track before it in the album. Krystal’s wistful tone is used well to make the song distinct. Sulli’s lighter voice and Victoria’s steady vocals are also used effectively, forming a contrast with Luna’s fuller tone and Amber’s distinct voice color. Taken together, there is a push and pull that remains steady throughout, all while there is a rising sensation of being boxed in. 

“Butterfly” is similar to “Shadow” in that there is an ease when you listen to it–a relaxed and unhurried vibe. What differentiates it is the slight edge to every note, a characteristic of Red Light. The song plays well with the almost pleading tone of every member’s vocals. The hook provides just the right contrast between the second and third choruses, reminiscent of their earlier B-side, “Love” (from Pinocchio). 

Their last release, 4 Walls from 2015, features a maturation of their sound as they celebrated their sixth anniversary. It also showcases where f(x) could have gone if only they were given more chances to promote, instead of being left to languish. This maturation of sound is seen in the trio of stand-out tracks: “Rude Love,” “X,” and “When I’m Alone.” They are all sensual, and yet of differing levels. 

Once one hears the opening bars of “Rude Love,” one thinks of disco balls, of colorful strobe lights, of sequined dresses and vibrant clothes. The track is sensual in the way Krystal and Luna sing “I want your rude love, tonight,” making it clear what this song is about. Like the lyrics, the song is musically active, a rush going through one’s system as the song builds and builds. It is the lively cousin of “4 Walls” that encourages you to dance along. 

On the other hand, “X” and “When I’m Alone” are more languid. “X” seemingly marinates in the lax tempo, in the lushness of its lyrics. There is a teasing tone, a casual seduction from the first note to the last. This is unbroken even in the chorus, although there is a slight push that makes the chorus melodically different. “When I’m Alone” is a mid-tempo ballad that is almost hushed in comparison to their booming tracks. Krystal’s voice is used well as a soft pleading next to Luna’s powerful notes, and Amber’s deeper tones contrast with Victoria’s steadiness. It is a languorous, pleasurable listen that reaches its climax with the elongated bridge and final chorus. 

While they are known for their dance tracks, the group also has the occasional mid-tempo ballad. “Goodbye Summer” from Pink Tape is one such song and features Exo’s D.O. The guitar is heard throughout, reminiscent of a summer breeze as Amber, Luna, and Krystal trade lines with D.O. This is not a song that is belted out (aside from the bridge), but rather, it is a wistful song that ruminates on the end of a relationship that never even began. 

Despite being on the same album, or perhaps due to them being on the same album, “Ending Page” is different from the nostalgic “Goodbye Summer.” This is due to the slight bite present in its notes, both musically and sung. This edge loosens in the chorus, as the music follows the sentimental lyrics:

Haven’t you ever felt lonely?
Haven’t you ever been like this when tears fall?
If we turn to the ending page of our novel, what kind of story will it be?

The song has Sulli singing in a deeper tone, while Luna’s voice is employed subtly so as to not overpower her. It also makes use of Krystal’s voice to emphasize the melancholy undercurrent. 

This is merely a small sampling of f(x)’s amazing discography during the six years that they promoted. Even with the members in different places of their careers and unknown variables, it is undeniable that f(x) has one of the strongest discographies with their unique sound and identity prominent in not just their title tracks, but also their B sides. 

(Colorcoded Lyrics, Images via SM Entertainment)