Line Level

An analog audio connection intended for connecting interconnecting audio equipment, and without the amplification required to connect to speakers.

Professional devices use dBu as the unit for signal level.

0 dBu = 0.775 Volts

The levels of professional devices are usually calibrated as +4 dBu.

+4 dBU = 1.228 Volts

The situation is slightly different for semi-professional and home devices. In this type of devices, dBV is used as the unit for signal height.

0 dBV = 1 Volt

Although it is not a rule, -10 dBV is generally used as reference level in semi-professional and home appliances.

-10 dBV = 0.316 Volts

Accordingly, there is a difference of 11.79 dB between the reference levels of professional and semi-professional/home devices. When these two different types of devices are connected to each other, there are inconsistencies in the levels due to the voltage differences between the reference levels.