From a representational viewpoint, the "voiced" series of obstruents in Shanghai dialect can be specified in terms of complementary, contextconditioned tonal and segmental features: either low tone or glottal pulsing. Yet, some studies have proposed that, when the "voiced" obstruents can only be signaled by low tone (stress-initially), they retain something of segmental voicedness. This somewhat mysterious "something" has often been identified to a moderate degree of breathiness after stop release, or "slack voice." In this study we revisit this issue and find that Shanghai obstruents, as produced today by young Shanghai people, indeed retain some characteristics of plain voiced obstruents but breathiness does not appear as the sole one. We propose that articulatory timing relationships are the main determinant to the mysterious voiced quality of Shanghai obstruents.