Abstract: A deflection unit for deflecting the electron beams in a cathode ray tube has a hollow coil support of a synthetic material. At one end, the support has projections around which a clamping apparatus is arranged for securing the deflection unit to the neck of the cathode ray tube. The clamping apparatus has projections located opposite each other, while their mutual distance determining the diameter of the clamping apparatus is adjustable by tightening a bolt. The ends of the projections are constructed in such a way that they support each other when the bolt is tightened.

Abstract: An electrodynamic transducer of the flat-diaphragm type in which the movement of the voice coil and coil former (2, 3) is transmitted to the flat diaphragm (1) via at least one auxiliary cone (8 or 20). The auxiliary cone is secured to a centering diaphragm (7) along its outer rim (10), if required via a coupling element (23). This is advantageous in the construction and the method of manufacturing the transducer. Moreover, a low-distortion transducer is obtained. A method of manufacturing the transducer is disclosed.

Abstract: An electro-acoustic transducer has a diaphragm which comprises a layer of a polymethacrylimide foam having a modulus of elasticity between 15.times.10.sup.6 and 120.times.10.sup.6 N/m.sup.2 and a density between 10 and 80 kg/m.sup.3. If the diaphragm has a sandwich construction, the core layer is made of said polymethacrylimide foam and the skin layers are made of glass fibres, carbon fibres, cellulose fibres or polyaramide fibres. This results in a transducer having a higher efficiency and a lower distortion.