Son de la Frontera (Sound of the Frontier) refers to Flamenco's historic collision of North African and Roma (Gypsy) traditions, plus Spanish-and-African derived Latin sounds imported from the Americas and Caribbean. Deeply inspired by the legacy of Diego Amaya Flores del Gastor (1908-1973), the group got its start in del Gastor's hometown of Morón de la Frontera in 1995, with two of Diego's descendants, Paco de Amparo (flamenco guitar) and Pepe Torres (baile & compás/ dance & rhythm), along with Raul Rodriguez (Cuban tres), Moi de Morón (cante & compás/vocals & rhythm) and Manuel Flores (compás/rhythm.) The distinctive sound of the Cuban tres was added to the ensemble after Rodriguez discovered the Latin instrument's dulcet tones through his mother, the renowned singer Martirio, who accepted an invitation to perform in Havana with Buena Vista's Compay Segundo, and brought one home with her. Rodriguez eventually realized that flamenco falsetas (scales and arpeggios roughly analogous to jazz riffs) could be freely adapted to the instrument's three sets of double strings. Thus, the final frontier was breached and Son de la Frontera achieved its musical destiny.

The title of their new CD, Cal, refers to a type of limestone whitewash/mortar that is repeatedly applied onto Spanish homes and other edifices. Applied by brush or trowel, this material builds up over many decades and eventually, a creamy patina is built up that not only catches and purifies the light but actually fortifies the structures it adheres to. The metaphor is a particularly apt one, as Son de la Frontera is constantly re-imagining its richly multi-cultural milieu while never failing to honor the rich Flamenco tradition that came before. Guided by the legacy of the great del Gastor, the group's trans-continental assembly of strummed strings can shift from dreamy introspection into paroxysms of fire-eating passion within a heartbeat. Intoxicating melodies and rhythmic cycles of staggering complexity unfold like epic tales from the legendary past. This time out, vocals are more prominent in the mix and, along with a bouquet of rarely-heard antique styles like the malagueña, taranto and sevillana, the set list also contains some original tunes composed by band members. From the opening frenzy of thundering heels and handclaps, the album is a never-to-be-exhausted treasure trove, a musical adventure during which each delighted epiphany is a prelude to the next.