Line level is a term used to denote the strength of an audio signal used to transmit analog sound information between audio components such as CD and DVD players, TVs, amplifiers, and mixing consoles. Depending on the application, line levels are stated in units of either decibel volts (dBV) or decibel volts unloaded (dBu). Consumer audio equipment line levels are rated in dBV, and the most commonly used reference level for such equipment is −10 dBV, which corresponds to a signal of about .3162 volts RMS. Professional audio equipment line levels are rated in dBu, and the most commonly used reference level for such equipment is +4 dBu, which corresponds to a signal of about 1.228 volts RMS.

Line level signals are often contrasted with weaker signals, such as those output from microphones and instrument pickups, and stronger signals, such as those used to drive headphones and loudspeakers.

Line-level in traditional signal paths

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Acoustic sounds (such as voices or a musical instruments) are often recorded with transducers (microphones and pickups) that produce weak electrical signals. These signals must be amplified to line level where they are more easily manipulated by other devices (such as mixing consoles and tape recorders). Such amplification is performed by a device known as a pre amplifier. After manipulation at line level, signals are then typically sent to a device known as a power amplifier, where they are amplified to levels that can drive headphones or loudspeakers, which convert the signals back into sounds that can be heard through the air.

Most phonographs also have a low output level and require a preamp; typically, a home stereo amplifier will have a special phonograph input with a built-in preamp, which also modifies the signal in order to account for the attenuation used in phonography of low-frequency signals.

References

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1. .

External links

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• Conversion of voltage to voltage level dBu, dBV, and dBm
• Units dBV in consumer equipment, dBu in professional equipment
• The Decibel

Electronics | Audio engineering | Sound

line level