Alternative musicians often seem intent on being nostalgic either for the past, or antiquated depictions of the future. On their debut LP, “In Heaven,” New York quintet Twin Sister set up pop tracks that embrace both the now-popular sounds of post-punk and a broader swath of past sounds. The album marries an even, computerized feel with genres as disparate as disco’s flair and Spaghetti Western scores. Their breadth makes for a fresh and offbeat production, but consistent elements in their songwriting keep the album from feeling like an unfocused jumble.

Delicate opener “Daniel” starts with sweet, clear synthesizer tones, and then introduces a shuffling electronic beat with soft keyboards trailing beneath it. By “Spain” and “Gene Ciampi,” more than halfway through the album, twanging guitar figures and sweeping strings replace the synthesizers with a cinematic European flair. “Daniel” and “Spain” mark the poles of the album’s improbable tonal spectrum, but Twin Sister muster enough instrumental versatility to pull off Spanish guitar as convincingly as tight, computerized beats.

While these tracks each devote themselves to one familiar aesthetic, the album’s most captivating songs smoothly consolidate elements of multiple styles. On these compositions—“Bad Street,” which pairs skittering synthesizers with a Talking Heads strut, and “Stop,” which puts strings and a funky bass line under a psychedelic keyboard jumble—the instrumentals are adeptly mixed, with each component holding down its own melody rather than seeming an afterthought or accent. Within themselves, the tracks bridge modern synth-pop and elegant facsimiles of past sounds.

But Twin Sister’s own sound exists beyond their collagic tendencies. The album is marked by consistent songwriting choices that cohere and sharply define the band’s modus operandi. Twin Sister impose a standard structure on many of their amalgamations, and their rock steady beats and short, cyclical instrumental lines that loop tirelessly drive each track confidently. And in all of their compositions, the band avoids gratuitous layering and inaccessibly thick, hazy soundscapes. Every instrument instead seems to have its own clearly discernible melody, and the resulting layered tracks feel both rich and streamlined. All these components are tied together by lead singer Andrea Estella’s tender, powerful vocals. She inflects her unwavering notes with wistfulness, desperation, or whim on almost every track. Her stellar vocal performance is thrown into sharp relief by the album’s weakest track “Eastern Green,” which features a flat male vocalist. Overall, these consistent techniques lend clear character to Twin Sister’s sound while the band liberally experiments with genre, and restrain the album from spiraling into chaos.

Their infrequent deviations from this consistent style weaken the album. On “Gene Ciampi” and “Saturday Sunday,” they let their pop sensibility shine, brilliantly if briefly. The former kicks off with a catchy, trebly guitar riff, full of risqué swagger, while the latter revels in lazy, summery guitar pop and builds to an irresistible chorus. However, the tracks’ indulgence in echo, fuzz, and overlapped melodies, and their underemphasized beats, seem incongruous with the rest of the album. The tracks stand strong individually, but since so much of “In Heaven” balances stylistic exploration with subtly strict structures, they feel confused and disjointed in the larger context of the album as a whole.

The music world seems ever inclined to invent subgenres using the suffix “pop”—synth-pop, dance-pop, chamber pop, dream-pop, Afropop—but “In Heaven” pleasantly and inconspicuously eludes clear categorization. The album never settles into one genre for long before flitting to another, but it works best when it doesn’t show off its juxtapositions, instead evenly mixing past and modern influences in a steady structure. Though they miss this narrow mark on occasion, Twin Sister’s ability to juggle so many genre hallmarks displays admirable finesse.

—Staff writer Austin Siegemund-Broka can be reached at asiegemund-broka@college.harvard.edu.