Residual Output Noise
Output noise voltage states the residual electrical noise measured at an output without a wanted signal.
It may be expressed in volts or a referenced voltage level such as dBV or dBu. Bandwidth, weighting and the input and control conditions determine which noise is included.
Residual Output Noise — Digital Audio Player
For a portable player, noise belongs to the specified analogue output and operating mode. Headphone and line outputs can have different noise levels.
Compare the same output, gain, volume and test conditions. Sensitive earphones can make small residual noise noticeable; this voltage is not the signal-to-noise ratio or a DC-offset measurement.
Residual Output Noise — Power Amp
For a power amplifier, output noise voltage is normally measured at the speaker terminals. Gain, input termination and measurement bandwidth affect the result.
Compare equivalent input and gain conditions and retain weighting. A lower voltage means less measured noise under those conditions, while perceived hiss also depends on the loudspeaker’s sensitivity.
Residual Output Noise — Headphone Amp
For a headphone amplifier, noise voltage describes residual noise at the specified headphone output. Gain and volume position can change the measurement.
Compare the same output mode, load and input condition. Sensitive headphones may reveal hiss more readily, and a noise voltage cannot become a signal-to-noise ratio without a stated signal reference.