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Glossary of Basic Microphone Terms Amplifier: a device that tracks the amplitude of an incoming signal and proportionally increases the vohage, current or power of the signal by adding power from another source Attenuation: the process of decreasing the amplitude of 2 signal as it passes from one point to another, Analog attenuation circuits typically use resistors to reduce the voltage of a signal. In audio, the effect of such attenuators is usually expressed in decibels, See decibel, resistor. Balanced line: An audio line comprising three conductors—two carrying signal and a ground (shield) wire, where one of the signal wires carries the sound and the-other carries an inverted copy..When. the signal reaches the destination, the inverted: copy is flipped and added to the original: Any noise that has been induced into the signal is also inverted. When this is combined with the "uninverted” noise, it cancels il out. Balanced lines thus are-iess susceptible to hum and can carry audio signals over longer distances. Balanced audio lines typically use 3-pin XLR or 1/4-inch tip-ring-sleeve (TRS) phone connectors Capacitor microphone: an alternate, less-used term for condenser micraphone. Cardioid microphone: a microphone with a directional pickup pattern that is most sensitive to sounds coming from the front and sides while rejecting s6unds coming from the rear, The pickup pattern is roughly heart-shaped when viewed from above, hence the name "cardivid.” ~ Condenser microphone: a microphone that picks up sounds via an electrically charged, metallized diaphragm, which is separated from a conductive back plate by a thin air layer. Sound waves striking the diaphragm cause @ minuscule voltage change, which is increased by a tiny amplifier circuit within the mic body. Because power is required by both the microphone capsule and the amplifier, condenser microphones must have @ power source, which can be a battery inside the mic body or "phantom" power from @ mixing console or extemal power supply. dB; abbreviation for "decibel." See decibel. dBm: a term expressing an elecirical power level, referenced to 1 millwatt (e., 0 dBm = 4 mW). Originally, dBm was used to express the power dissipated in telephone applications with 600-chm impedances, but it is not necessarily referenced to a particular impedance. dBu: a means of expressing voltage referenced so that 0 dBu equals 0.775 volts, regardless of impedance. One mW of power is dissipated if 0.775 volts is applied to a 6G0-ohm load, so when the load impedance is 600 ohms, 0 dBu = 0 dBm. BV: a means of expressing voltage, referenced so that 0 dBV equals 1-volt RMS, regardless of impedance. By: synonymous with dBu but rarely used due to confusion with dBV. See dBu. decibel: a unit of measure used to logarithmically express ratios of change. in power or signal levels, Equal to one- tenth of a Bel (named for Alexander Graham Bell). Dynamic microphone: a transducer that relies on the law of induction, with.an output. proportional fo the velocity of a moving element within 2 magnetic field. The most common type is the moving-coil micraphone, which picks up sounds when sound waves strike a diaphragm attached to a coil of wire. When the coil moves within the magnetic structure-of the microphone, it creates an output voltage. The process’ is exactly the reverse of the way.a speaker operates, Moving-coll dynamic micrabhone’ fend to be extremely rugged; making them well-suited for most sound reinforcement applications. The other common type of dynamic microphone .is the ribbon mic. See ribbon microphone. Dynamic ‘range: 4 ratio (expressed in’ ds) of the difference betwéen the softest and the ;oudest Solind that cein be produced, reproduced or captured by a musical instrument or diidio device Feedback: 2 condition where the output of a circuit recycles through its input. Acoustic feedback is a whine or howl that occurs in live audio: situations when’ an amplified sound re-enters a. sound systém through the .same microphone (or guitar pickup} that reproduced thé original source, creating a loop. Feedback also. can.be usedin 
