Abstract: Various implementations include speaker systems. In one implementation, a self-powered speaker system includes: a self-powered speaker system, having: a first module, including: a processor; an audio signal and control connector coupled with the processor and enabling audio signal and control communication between the processor and another module in the speaker system; a dedicated power supply for the speaker system; a front end backup power supply; and a power connector coupled with the dedicated power supply and the front end backup power supply, where the first module and another module in the speaker system each include an amplifier module.

Abstract: Various implementations include speaker systems. In one implementation, a self-powered speaker system includes: a self-powered speaker system, having: a first module, including: a processor; an audio signal and control connector coupled with the processor and enabling audio signal and control communication between the processor and another module in the speaker system; a dedicated power supply for the speaker system; a front end backup power supply; and a power connector coupled with the dedicated power supply and the front end backup power supply, where the first module and another module in the speaker system each include an amplifier module.

Abstract: Various implementations include speaker systems. In one implementation, a self-powered speaker system includes: a first module, having: a processor; an audio signal and control connector coupled with the processor and enabling audio signal and control communication between the processor and another module in the speaker system; a dedicated power supply for the speaker system; a front end backup power supply; and a power connector coupled with the dedicated power supply and the front end backup power supply, the power connector enabling input power to the dedicated power supply and output power from the front end backup power supply.

Abstract: Various implementations include speaker systems. In one implementation, a self-powered speaker system includes: a first module, having: a processor; an audio signal and control connector coupled with the processor and enabling audio signal and control communication between the processor and another module in the speaker system; a dedicated power supply for the speaker system; a front end backup power supply; and a power connector coupled with the dedicated power supply and the front end backup power supply, the power connector enabling input power to the dedicated power supply and output power from the front end backup power supply.

Abstract: There is disclosed a method of distributing a liquid composition over the ground from travelling equipment, the composition comprising an active ingredient, in which method the concentration of the active ingredient in the liquid composition is varied in dependence on the speed of the travelling equipment over the ground, the liquid composition also comprising a viscosity modifying agent, the method comprising varying the relative proportion of the viscosity modifying agent in the liquid composition in dependence on the speed of the travelling equipment, thereby to control the viscosity of the liquid composition. Also disclosed is equipment for use in the aforesaid method.