If late summer is the season of contrasts, Ratatat is September’s soundtrack.

In the same way chilly fall nights creep into these last humid days, this Brooklyn duo sneaks panther howls and maracas into otherwise steady and calm electronic music.

Guitarist Mike Stroud and producer Evan Mast team together to create music that is almost completely indescribable. It has no words that can be referenced, no consistent melodies that can be hummed – just beats, just noise, just layers and layers of rhythmic guitar.

Ratatat released their first, self-titled album in 2004, followed by the latest, “Classics.” Both combine multidimensional heavy guitar with fat slabs of organ beats, while somehow keeping the tracks remarkably light and easy-breezy.

At its widest, there are 70 samples playing at one time on “Classics.” While they have hired a third member, Jacob Morris of New York-based band the Double, to play keyboard with them on tour, there wouldn’t be a stage large enough in the country for every sound to be played live.

“Classics” features a contrast of themes, from the heavy-metal blast of guitars on “Lex” to the mellow back-and-forth groove of “Loud Pipes.”

Ratatat is best known for their single “Seventeen Years,” the duo’s danciest track to date. On it, they created a guitar riff that worked really well unaccompanied, but refused to leave it alone – it begins to repeat over and over, backed by heavy bass beats, while more and more sounds are added and taken away.

Ratatat is complicated rock ‘n’ roll alchemy. Their songs don’t “go like this,” they “do like this.”