Mackie SR408 / SR568 Owner's Manual - Page 67

Haas effect A psychoacoustic effect in which the time of arrival of a sound to the left and right ears affects our perception of direction. If a signal is presented to both ears at the same time at the same volume, it appears to be directly in front of us. But if the signal to one ear, still at the same volume, is delayed slightly (0 to 5 msec), the sound appears to be coming from the earlier (non-delayed) side. headroom The difference between nominal operating level and peak clipping in an audio system. For example, a mixer operating with a nominal line level of +4dBu and a maximum output level of +22dBu has 18dB of headroom. Plenty of room for surprise peaks. Hertz The unit of measure for frequency of oscillation, equal to 1 cycle per second. Abbreviated Hz. KHz is pronounced "kay-Hertz" and is an abbreviation for kilohertz, or 1000 Hertz. house In Sound Reinforcement parlance, "house" refers to the systems (and even persons) responsible for the primary sound reinforcement in a given hall, building, arena or "house." Hence we have the house mixer or house engineer, the house mix, the house mix amps, the main house speakers and so on. Hz See Hertz. impedance The A.C. resistance/capacitance/inductance in an electrical circuit, measured in ohms. In audio circuits (and other AC circuits) the impedance in ohms can often be much different from the circuit resistance as measured by a DC ohmmeter. Maintaining proper circuit impedance relationships is important to avoid distortion and minimize added noise. Mackie input and output impedances are set to work well with the vast majority of audio equipment. input module A holdover from the days when the only way that real consoles were built was in modular fashion, one channel per module. See channel strip. knee A knee is a sharp bend in an EQ response curve not unlike the sharp bend in your leg. Also used in describing dynamics processors. level Another word for signal voltage, power, strength or volume. Audio signals are sometimes classified according to their level. Commonly used levels are: microphone level (-40dBu or lower), instrument level (-20 to -10dBu), and line level (-10 to +30dBu). line level A signal whose level falls between -10dBu and +30dBu. main house speakers The main loudspeakers for a sound reinforcement system. These are usually the largest and loudest loudspeakers, and are usually positioned so that their sound seems to come from the area of the main stage. mains See main house speakers. master A control affecting the final output of a mixer. A mixer may have several master controls, which may be slide faders or rotary controls. mic amp See mic preamp. mic level The typical level of a signal from a microphone. A mic level signal (usually but not always coming from a microphone) is generally below -30dBu. With a very quiet source (a pin dropping?) the signal can be -70dBu or lower. It is also possible for some microphones to deliver more signal than this, in which case it may be referred to as a "hot" mic level. Alternatively, you can just say, "Boy, is that loud!" mic pre See mic preamp. mic preamp Short for microphone preamplifier. An amplifier that functions to bring the very low signal level of a microphone (approximately -50dBu) up to line level (approximately 0dBu). Mic preamps often have their own volume control, called a trim control, to properly set the gain for a particular source. Setting the mic preamp gain correctly with the trim control is an essential step in establishing good noise and headroom for your mix. 67