Abstract: A linear control arrangement, of which a plurality may be provided in an audio mixing console, includes a fader potentiometer having a knob in which a tactile switch is recessed. The switch enables and inhibits recording and/or amending of the fader movement history, and allows ready overwriting or other amendment of existing fader movement data when required. The arrangement allows single finger operation of both the knob and the switch, as well as overcoming the need to provide separate space on the panel for the switch.

Abstract: In a digital-to-analog conversion system, an input digital signal D is separated by means of an inverter into first and second signal paths, one of which is the inverse of the other. A digital random noise signal R is then added to the direct and inverse signals to form combined digital signals R-D, R+D. The combined signals are converted into analog form by two identical D/A converter devices to provide analog signals R-D+E1, R+D+E2 (E1 and E2 representing the errors introduced in the conversion process), and these are then subtracted to form an analog output 2D-E1+E2. Thus the random noise components are removed from the analog output, and also the errors E1 and E2 tend to cancel each other leading to a reduction in distortion. Moreover, any remaining distortion is randomized and thus harmonic distortion is reduced. When the injected random noise signal has a greater resolution than the converter devices, there is also an overall increase in data resolution.