G l o s s a r y . . .
dBu or dBv
The addition of a lower case ”u” or “v” after dB indicates an absolute scaling for the dB ratio. 0dBu (or 0 dBv) = 778mV or 0.778 Volts, and it has no regard for power or impedance. This term is widely used for expressing signal voltages in modern audio equipment with high input impedances and low output impedances. For dBv the same scale is used as for dBu above, except that 0dBV = 1.0 Volts.
Distortion
Any modification of a signal which produces new frequency components not present in the original. Harmonic distortion refers to added frequencies that are overtones to the fundamental frequency. Intermodulation distortion refers to added frequencies that are sum and difference values derived from the beating together of two frequencies.
Frequency
The repetition of a waveform. The unit of frequency is Hz, and 1 cycle per second is equal to 1Hz. The audio band is generally restricted to frequencies of 20Hz to 20,000Hz (20kHz).
Frequency Response
The equipment’s relative gain compared to frequency. Generally expressed as +/- a certain number of dBs from 20Hz to 20kHz.
Impedance
The AC equivalent of resistance and measured in ohms. It indicates the amount of drive required for an input, or the drive capability of an output, at a given signal level.
Level
The amplitude of a signal, measured in Volts or Decibels.
Line Level
Generally indicates a signal whose level is between
Noise
The term given to any signals appearing at the output of a piece of equipment when no input signal is applied. Most commonly, noise takes the form of hum, buzz or hiss.
Octave
A logarithmic unit for expressing frequency ratios. Positive values indicate an increase and negative ones a decrease. One octave ‘up’ the scale is equivalent to double the frequency. One octave ‘down’ is equivalent to half the frequency.
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