are deliberately not matched from output to input. The impedance of a line input is typically around . When driven by a line output's usual low impedance of 100 to 600 ohms, this forms a bridging connection in which most of the voltage generated by the source (the output) is dropped across the load (the input), and minimal current flows due to the load's relatively high impedance. Although line inputs have a high impedance compared to that of line outputs, they should not be confused with so-called "Hi-Z" inputs (Z being the symbol for impedance) which have an impedance of to over . These "Hi-Z" or "instrument" inputs generally have higher gain than a line input. They are designed to be used with, for example, electric guitar pickups and "direct input" boxes. Some of these sources can provide only minimal voltage and current and the high impedance input is designed to not load them excessively. Line level in traditional signal paths Acoustic sounds (such as voices or 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 preamplifier or "preamp", which boosts the signal to line level. After manipulation at line level, signals are then typically sent to a power amplifier, where they are amplified to levels that can drive headphones or loudspeakers. These convert the signals back into sounds that can be heard through the air. Most phonograph cartridges also have a low output level and require a preamp; typically, a home stereo integrated amplifier or receiver will have a special phono input. This input passes the signal through a phono preamp, which applies RIAA equalization to the signal as well as boosting it to line level. See also Nominal level Alignment level Microphone Preamplifier Amplifier Soundcard References External links Conversion of dBu to volts, dBV to volts, and volts to dBu, and dBV Conversion of voltage V to dB, dBu, dBV, and dBm The Decibel Electronic engineering Audio engineering Sound Consumer electronics Signal cables