Acoustic loudspeaker comprising: a movable membrane; a source of constant magnetic field, a coil mechanically secured to said membrane and interacting with the magnetic field so as to displace the membrane, when it is traversed by an alternating current, characterized in that the membrane carries the coil at its periphery, and in that the magnetic field source is formed by a set of at least one magnetized element disposed at the periphery of said membrane, around the coil, the magnetic field generated by said at least one magnetized element being in a plane parallel to the membrane.