A switching converter includes a transistor arrangement having a plurality of n transistors, with n\u22672, each including a gate terminal, and a load path between a source and a drain terminal, and at least m, with m\u2266n and m\u22671 of the n transistors having a control terminal. The signals are arranged to set a coupling strength of the coupler. The frame assembly has a main channel extending therein. The printed circuit board and having a curved shape to partially circumscribe the speaker means to enable the speaker means and the circuit board to lie co-planar.