Mackie DL32R Owners Manual - Page 32

DL32R Owner's Manual Glossary Of Terms Continued... Nyquist Sampling Theorem - This theorem states that, when an analog signal is converted to a digital signal, it must be sampled at a frequency that is at least twice the highest audio frequency present in the analog signal. If the audio frequency should exceed one-half the sampling frequency, aliasing may result. Thus, if an analog-to-digital converter is sampling at 44.1 kHz, the audio signal should not exceed 22.05 kHz. PA - Acronym for Public Address. Today, people who work with PA systems like to say they're working in "sound reinforcement". See SR. Pan - Pan sliders are used to position (or even dynamically move) a monaural sound source in a stereo mixing field by adjusting the source's volume between the left and right channels. Our brains sense stereo position by hearing this difference in loudness when the sound strikes each ear, taking into account time delay, spectrum, ambient reverberation and other cues. Peaking - The opposite of dipping. A peak is an EQ curve that looks like a hill, or a peak. Peaking with an equalizer amplifies a band of frequencies. PFL - An acronym for Pre-Fade Listen. Broadcasters call it cueing. Sound folks call it being able to solo a channel with the fader down. Phantom Power - A system of providing electrical power for condenser microphones (and some electronic pickup devices) from the microphone input jack. The system is called phantom because the power is carried on a standard microphone audio wiring in a way that is "invisible" to ordinary dynamic microphones. The DL Series mixers use a standard +48 volt DC power, switchable on or off. Generally, phantom power is safe to use with non-condenser microphones, as well, especially dynamic microphones. However, unbalanced microphones, some electronic equipment (such as some wireless microphone receivers) and some ribbon microphones can short out the phantom power and be severely damaged. Phase - The time relationship between two signals, expressed in degrees around a circle. 0˚ and 360˚ represent an in-phase relationship. Both signals change in the same way at the same time. Anything else is out of phase. 180˚ out-of-phase is a special case which, for a continuous waveform, means that at any given time the two signals have the same amplitude but are opposite in polarity. The two legs of a differential output are 180˚ out-of-phase. The polarity invert button (found in the EQ view) reverses the signal polarity. When out-of-phase signals are mixed, there will be some cancellation at certain frequencies, the frequencies and the degree of cancellation being a function of the amount of phase shift and the relative amplitude of the signals. Attention to mic placement and careful listening will allow you to use this effect creatively. Post Fader - A term used to describe an aux send (or other output) that is connected so that it is affected by the setting of the associated channel fader. Sends connected this way are typically (but not always) used for effects. A post-fader output from a mixer channel is usually post-EQ. Pre DSP - Pre DSP is ideal when using the auxes for monitor mixes and you want compression and other effects in the main mix, but not the monitors. Pre DSP is available in all auxes, but not the FX. Pre Fader - A term used to describe an aux send (or other output) that is connected so that it is not affected by the setting of the associated channel fader. Sends connected this way are typically (but not always) used for monitors. Q - A way of stating the bandwidth of a filter or equalizer section. An EQ with a Q of .75 is broad and smooth, while a Q of 10 gives a narrow, pointed response curve. To calculate the value of Q, you must know the center frequency of the EQ section and the frequencies at which the upper and lower skirts fall 3 dB below the level of the center frequency. Q equals the center frequency divided by the difference between the upper and lower 3 dB-down frequencies. A peaking EQ centered at 10 kHz whose -3 dB points are 7.5 kHz and 12.5 kHz has a Q of 2. 32