by John Bush Juana Molina's sound is so precious and rare that tampering with the formula is akin to tearing down a singular example of great architecture, or witnessing the extinction of a rare and beautiful animal. Fortunately, Un Dia is immediately recognizable as a Juana Molina album. Yes, there are slight differences between this and her previous work, but fortunately, she's still retained most of what made her special in the past. In place are the gentle but propulsive vocal-based rhythms, the airy feel to the proceedings, and the occasional chirping polyharmonies. Also present (and appreciated) is the fine balance between organic instruments (wood, metal) and post-production processing (delays, distortion) that makes her records sound as experimental as Björk's but much more inviting. Differences appear, however, in the hypnotic rhythm that powers several songs with a driving energy. If her breakout albums, 2000's Segundo and 2002's Tres Cosas, were so diaphanous that they threatened to dematerialize altogether, Un Dia makes rhythm a central proposition, sometimes so machine-like that she approaches techno (albeit, techno from the standpoint of an Argentinean obsessed with native instruments).