Volume and Balance Controls
A volume control is the most essential knob on a preamplifier – in fact the unhappily named ‘passive preamplifiers’ usually consist of nothing else but a volume control and an input selector switch. Volume controls in one guise or another are also freely distributed on the control surfaces of mixing consoles, examples being the auxiliary sends and the faders.
A volume control for a hi-fi preamplifier needs to cover at least a 50 dB range, with a reasonable approach to a logarithmic (i.e. linear-in-dB) law, and have a channel balance that is better than ±1 dB over this range if noticeable stereo image shift is to be avoided.
The simplest volume control is a potentiometer. These components, ...