Sources of Noise

Author: N.H. Crowhurst

Anything that is in an electrical circuit can be a source of noise. In most components the effective noise is in some way related to their resistance. A resistor, regardless of its dimensions, produces a certain noise energy, dependent on its temperature. Any resistance produces noise in this way - the resistance of transformer windings, of the coils in microphones and pickups, and so on.

Components with resistance are source of noise energy

As most audio equipment is operated at room temperature and the noise voltages cannot be measured very precisely anyway, we need only deal with an average figure. The energy output depends on the overall range of frequencies involved. If we use measurements that include frequencies from 0 to 20,000 cycles, the energy will be twice that for frequencies from 0 to 10,000 cycles.