A connector (10) for a duct (1) for the pneumatic feeding of fibre to at least one carding machine (2) has an upstream portion (14) and a side duct (18) having a through opening (20) for fibre feeding to the carding machine (2).The connector comprises "stepped" means (22) for deflecting the stream of fibre, and lead-in bevels (41, 42) or a closing wall (100) inclined for the end-of-line connector, in order to even out the density of fibre sent to the carding machine.