Abstract: An audio signal processing apparatus comprises at least one controllable element 90, 91, 92 for performing an analogue audio processing function. The controllable element is operable with a digital controller 58 that controls the analogue audio processing function performed by the controllable element 90, 91, 92. At least one audio processing module 52, 54 comprises a partial audio processing circuit for an audio processing operation. The module 52, 54 is operable with the controllable element 90, 91, 92 to complete the audio processing circuit and thus to enable the audio processing operation. In this way the audio processing operation is controllable by the digital controller. A switching array 96 selectively couples audio processing modules 52, 54 and the controllable elements 90, 91, 92. A power supply 66 is operable to supply power selectively for audio processing circuit of the or each module 52, 54.

Abstract: A fluid heating apparatus comprising a chamber for containing a quantity of fluid to be heated and a heating device in the chamber. The heating device comprises a hollow body having a flow inlet and a return outlet to allow a heating medium to flow through the hollow body. The hollow body has a first heat exchanging surface extending along the chamber between a fluid inlet and fluid outlet and defining a smooth, straight fluid passage between the inlet and outlet. The preferred apparatus takes the form of a thermosyphon and is particularly suited for use with a water storage tank, where it is arranged to cause thermosyphonic circulation of water between the thermosyphon and the tank.