The present invention provides for a connector block for retaining at least one shock tube in signal transmission relationship with the percussion-actuation end of a detonator. The connector blocks of the present invention comprise a slot (7, 26, 46, 64, 87) for the retention of shock tubes therein, wherein the slot is configured to induce a bend (8a, 27a, 47a, 91a) in the shock tube(s). In this way, the position of the shock tube(s) relative to the detonator is significantly improved. Air gaps between the shock tubes and the detonator, resulting from manufacturing tolerances, can be substantially eliminated. Moreover, the connector blocks of the present invention provide an increased security of shock tube retention, thereby reducing the risk of accidental shock tube removal or displacement.