An electromechanical transducer, comprising: at least two flux modules, each defining a magnetic circuit having a gap; and a movable member configured to move along a longitudinal axis passing through the gaps, the movable member having a plurality of magnets of alternating polarity mounted within the movable member, wherein the at least two flux modules comprises one or more flux module pairs; one flux module of the pair comprises coils only on one side of a plane parallel to the width of the gap and the longitudinal axis; and the other flux module comprises coils only on the other side of the plane, wherein each of the flux modules comprises a first core defining the gap and a second core for supporting coils for linking with or generating flux in the magnetic circuit of the flux module, characterized in that: the transducer further comprises a gas containment structure laterally surrounding the movable member; the at least two flux modules are provided outside the gas containment structure; the movable member comprises a reinforcing portion laterally outside of the gaps that is wider in a direction parallel to the flux in the gaps than at least one of the gaps; the gas containment structure is supported by elements, i.e. the flux modules and/or a frame for supporting the flux modules, that are laterally external to the gas containment structure over the whole outer surface of the gas containment structure for a predetermined longitudinal distance in order to resist deformation of the gas containment structure due to a pressure difference between the inside and the outside of the gas containment structure over the predetermined length; and the flux modules and/or the frame provide a surface that is flush against all of an outer surface of the gas containment structure over the predetermined longitudinal distance in order to provide the support. at least two flux modules, each defining a magnetic circuit having a gap; and a movable member configured to move along a longitudinal axis passing through the gaps, the movable member having a plurality of magnets of alternating polarity mounted within the movable member, wherein the at least two flux modules comprises one or more flux module pairs; one flux module of the pair comprises coils only on one side of a plane parallel to the width of the gap and the longitudinal axis; and the other flux module comprises coils only on the other side of the plane, wherein each of the flux modules comprises a first core defining the gap and a second core for supporting coils for linking with or generating flux in the magnetic circuit of the flux module, characterized in that: the transducer further comprises a gas containment structure laterally surrounding the movable member; the at least two flux modules are provided outside the gas containment structure; the movable member comprises a reinforcing portion laterally outside of the gaps that is wider in a direction parallel to the flux in the gaps than at least one of the gaps; the gas containment structure is supported by elements, i.e. the flux modules and/or a frame for supporting the flux modules, that are laterally external to the gas containment structure over the whole outer surface of the gas containment structure for a predetermined longitudinal distance in order to resist deformation of the gas containment structure due to a pressure difference between the inside and the outside of the gas containment structure over the predetermined length; and the flux modules and/or the frame provide a surface that is flush against all of an outer surface of the gas containment structure over the predetermined longitudinal distance in order to provide the support. the transducer further comprises a gas containment structure laterally surrounding the movable member; the at least two flux modules are provided outside the gas containment structure; the movable member comprises a reinforcing portion laterally outside of the gaps that is wider in a direction parallel to the flux in the gaps than at least one of the gaps; the gas containment structure is supported by elements, i.e. the flux modules and/or a frame for supporting the flux modules, that are laterally external to the gas containment structure over the whole outer surface of the gas containment structure for a predetermined longitudinal distance in order to resist deformation of the gas containment structure due to a pressure difference between the inside and the outside of the gas containment structure over the predetermined length; and the flux modules and/or the frame provide a surface that is flush against all of an outer surface of the gas containment structure over the predetermined longitudinal distance in order to provide the support.