Lexikon Line-In/Line-Out specifications

Category : Lexicon

Line-in and line-out are English terms for high-level inputs and outputs. In Hi-Fi devices, these are the connections for tuners, tape recorders, CD players, etc.

The characteristics of these inputs and outputs are internationally specified in the IEC -61938 standard, which does not necessarily mean that all manufacturers comply with it. The standard specifies a reference level of 0.5V (-6dBV) and requires:

It depends on the type of device how the standard level is to be understood. In the case of a tape recorder, the standard level is reached, for example, when playing a calibration tape, in the case of a CD player, the standard level is set as 12dB below the maximum level (i.e. -12dBFS). This means in particular that the standard level is not the highest permitted or technically possible level, but rather the level used in normal operation with good modulation. The difference between the standard level and the maximum level is called the headroom.

An older rule sets the reference level at -10dBV, which is still in use today as a standard level for consumer devices.

Some Hi-Fi devices do not have high-level outputs, mainly turntables and microphones. These must therefore be connected to special inputs of an amplifier, the signal is not suitable for high-level inputs.

See also the Wikipedia articles: Line level

Outputs have an output impedance of a maximum of 2.2kOhm
Inputs have an input impedance of a minimum of 22kOhm and an overload resistance of at least 2.8V