ABSTRACT
The human ears are very good at detecting distortion and things like balance - the relative loudnesses of sources - and also perspective. At the lower end there is the noise inherent in the system and at the upper end there is the level which the system just cannot handle properly without distortion. A volume unit meter is really only a voltmeter with a special scale. The latter can vary somewhat but the more usual versions have a decibel scale with a red section towards the right, this ostensibly showing the potential overload region. There is a lower noise level caused by the fact that the magnetic particles on the tape are sufficiently large for each one to contribute its own minute spike of voltage, although ground down in the manufacturing process to a very fine powder. Zero level is used almost universally as the correct voltage.
