Elac Concentro S 503.2Concentro 2. 0 S503. 2 Bookshelf Speaker There is no doubt about itthe S 503 is a true Concentro in every respect, in a much smaller package. Design features and technical details that drove the success of the Concentro S 507 and S 509 are now provided in a more compact size. MODERN HYBRID DESIGN The progressive design elements from the Concentro Series combined with the clean lines of the Vela Series to create a strong visual presence. The trapezoid