A wonderful set for audio engineering students covering compression, gating, equalization, expansion, and more.
A frequency-selective amplifier used to alter the frequency characteristics of the signal that passes through it.
Device used to proportionately reduce the dynamics of a signal that rises above a user-defined level (threshold) to a lesser volume range; Makes loud sounds softer and soft sounds louder.
Compressor with a high ratio setting; Used to suppress dynamic levels of a reproduced sound above a preset limit in order to provide a more constant output level; When the ratio setting exceeds 8:1 the device will function as a limiter.
Used to attenuate unwanted low-level information from the signal path; Will open when incoming signal exceeds the threshold setting allowing the signal to pass through it unmolested.
A device that changes some quality or aspect of a sound; Can be a mixing console, equalizers, reverberation, delay, and/or amplifiers.
A type of equalizer that allows an operator to select one particular frequency and boost or lower that frequency.
A type of fixed-frequency equalizer; Consists of sliding controls that boost or attenuate selected frequencies.
Allows only high frequencies to pass, chopping off lower frequencies (ex. => eliminate a low pitch rumble).
Allows only low frequencies to pass, chopping off the higher frequencies (ex. => eliminate a hiss).
Consonant sound in English produced by completely stopping the flow of air from the lungs and then releasing it; English examples include P, B, T, D, K and G.
Characterized by a hissing sound; noting sounds like those spelled with "S" and "F"
The range of sounds from softest to loudest that a recording format or system can reproduce suitably; the variation of amplitude over time.
Device Dynamic Range
The amplitude distance between the noise floor (the lowest voltage) and the maximum signal level before distortion (highest voltage).
Analog Tape Dynamic Range
The amplitude distance between tape hiss (the lowest fluxivity) and the point where saturation begins (the highest fluxivity).
The measure of the flux density of a magnetic recording tape, per unit of track width.
The intrinsic noise of any audio device or other electronic system, generally measured in dBm.
The maximum level for any piece of equipment; the type & actual amount of distortion varies according to the type of unit, what type of test standard is used, and the manufacturer.
The ideal average signal level; Usually referred to as the "0" level.
The amplitude distance between the nominal level and maximum level.
The amplitude distance between the nominal level and the noise floor.
Sets the AMPLITUDE level at which the compressor will begin to function (whenever the input signal is of higher amplitude than the threshold setting, the unit begins to work).
Determines the ratio of input level to output level; Tells the unit how much gain reduction to apply to a signal.
Compression Attack Time
Controls how quickly the compressor reacts once the incoming signal has exceeded the threshold setting.
Compression Release Time
Determines how long compressor will continue to compress and tells it when to stop compressing the signal.
Compression Output Gain
Used to bring the compressed signal level up.
Use of a separate circuit within a compressor/limiter to protect from any sudden high-level transients too fast or loud for the compressor to catch.
Reduces gain when the signal drops below the threshold setting.
Adjusts the amount of gain reduction that will occur when input signal drops below the threshold; how much the gate will "close".
Gate Attack Time
Tells the gate how quickly it should open once the threshold level has been surpassed.
Gate Hold (Sustain)
Determines how long the gate will stay open after the signal has gone below the threshold.
Gate Release Time
Determines how quickly the gate will go from open to the amount of attenuation set by the range control; Long Release = Fade Out Effect; Short Release = Sudden Cut-Off of Sound
Reverses how a gate operates; Used to lower the level of one sound while another occurs, such as lowering background music while an announcer is speaking.
A noise gate that amplifies the signal above the threshold in addition to attenuating the signal below the threshold; Makes soft sounds softer and loud sounds louder.
A compressor that reacts to a selected range of frequencies, usually used to reduce the sibilant frequencies of a vocal/voiceover track.
Compares the amplitude of the incoming signal with the threshold setting, then decides if the unit should process the signal or not.
Allows external access to the detector circuit, allowing one to control the operation of the dynamic processor with an external source.
Patching of Dynamic Processors
The most likely place to patch a dynamics processor is using the insert sends and returns of an I/O module; Usually patched in-line.
3dB Down Point
The frequency affected 3dB less than the center frequency; Measured at two points on each side of a frequency Bell curve and the distance between them determines the bandwidth.
An equalization characteristic that affects the center frequency the most; EQ has less and less affect on the signal passing through it as it moves away from center frequency.
An equalization characteristic that affects all frequencies above or below the 3 dB down point equally.
The 3dB Down Point in shelving EQs.
Real Time Analyzer
Audio device that measures and displays the frequency spectrum of an audio signal via a microphone; Provides the engineer with a constant display of frequency response. (RTA)
EQ Amplitude Control
Provides a certain amount of cut or boost per frequency, usually +12dB to +18 dB.
(Q) Quality Factor
Width of a peaking filter's bell shaped curve; The higher the Q, the narrower the bandwidth.
An attenuation only circuit that can be used to attenuate certain information from the signal passing through it; Does not affect the signal equally outside the 3 dB down point.
Created when a low and high pass filter are used together; The highs and lows are attenuated, allowing the band in the middle to pass.
Designed to attenuate a very narrow band of information
Loudspeaker Filter Slope
Gentle ~ 6dB per octave
Console Filter Slope
12dB per octave ~ Popular on consoles, equalizers, and loudspeakers.
Crossover Filter Slope
18dB per octave ~ Too dramatic for console use and sounds unnatural.
Anti-Aliasing Filter Slope
48dB per octave ~ Much too extreme to use in normal day to day operation.
The study of how humans perceive and process sound.
Time frame in which the listener will perceive no change in the sound, except the volume change that occurs when two waveforms are added together; Exists in the range of approximately 0 to 9 milliseconds.
When a direct sound and its reflective sound are between 9 - 32 milliseconds apart, it is perceived as one sound.
A delay-based effect produced by mixing 2 identical signals together, with one signal delayed by a small and gradually changing period of time (usually between 3 and 8 milliseconds).
An effect that will create the impression that multiple instruments are playing the same part; Created by having several versions of the original dry signal occur at different times and each one being slightly detuned from the other; Two or more delays each with different time periods (between 20 and 60 milliseconds) can be used to create this effect.
Low Frequency Oscillator
Low Frequency Oscillator
An electronic signal, which is usually below 20 Hz and creates a rhythmic pulse or sweep.
Slap Back Echo
A very short delay time with a single repeat; Can occur at delay times between 40 and 150 milliseconds, depending upon the nature of the original sound source.
3 Ways to Determining Delay Time
1.) 60,000 ÷ BPM 2.) Clock 10 beats with a digital stopwatch and ÷ 10 3.) Set delay time by ear.
Does not decay naturally as the closing of a gate cuts off the trailing reflections; Normally controlled by room size and diffusion; Not as dramatic and smooth sounding as true gating; Very popular effect with drums.
Occur when the effect comes before the dry sound; Creates an effect of the sound swelling into itself.
Taking a particular frequency band and changing the phase relationship of that band with the original signal, creating a comb filtering effect; Cancellations take place in a specific frequency band; Sounds like two instruments playing the same rhythm & gradually shifting out of unison.
Similar to a phase shifter, except that there is no internal oscillator; The musician controls the center frequency and sweep rate with a pedal, allowing for very expressive phrasing.
Time Based Processor
Used to alter the timing of signals passing through them; Time-shifted version of the signal (wet) is usually blended with the original (dry) signal to create the various effects.
Hold the signal sent to them for a period of time and then the signal travels to the processor's output; May also be re-routed back through the unit to be delayed again and again, creating multiple repeats (echoes) of the signal.
Thermal Semiconductor Charge Loss
The loss of information due to the electrical energy being converted to heat inside each capacitor.
Sample the information that is sent to them and hold that information in the digital domain.
Delay Input Level
Varies the signal level entering the unit for optimum signal to noise/headroom settings.
Delay Time Setting
Determines how long it is until we hear a repeat, as well as the time between repeats (or echoes).
Adjusts the percentage of output signal that will be re-routed back to the input; Determines the number of repeats, or echoes, that we hear; Commonly expressed as a percentage.
Delay X2 Button
Doubles the delay time when pressed by cutting the sampling rate in half.
Delay Mix Control
Adjusts the balance of wet and dry signals at the delay's output.
Delay Output Phase Switch
Reverses the polarity of the delayed signal.
Delay Sample and Hold
Tells the device to play back the sample currently in its memory over and over again much like a tape loop.
Delay Modulation Section
Allows the engineer to create interesting effects, where the delay time is modulating (changing) rather than staying at one fixed value; Controlled by depth, rate, and waveform.
Created when a sound produced in an enclosed space causes a large number of echoes to build up and then slowly decay as the walls and air absorb the sound; Changes the perceived harmonic structure of a note, but does not alter the pitch.
The time required for reflections of a direct sound to decay by 60 dB below the level of the direct sound. Reverberation time is either defined for wide band signals or for a one-third octave band centered at 500 or 1,000 Hz.
Proportional to the dimensions of the room and inversely proportional to the amount of absorption present.
Created with a small, highly reflective room, a speaker, and one or more microphones placed inside; Dry signal is sent into the speaker for the room to reverberate it and microphones pick up the sound.
An electro-mechanical device where the signal is sent through a coil of wire (a spring) with a transducer at each end; Commonly found in guitar amps.
An electro-mechanical device that uses a transducer to create vibration in a large plate of sheet metal; A pickup captures the vibrations as they bounce across the plate.
Mathematical algorithms that approximate the boundaries and acoustic characteristics of a space.
Time, Energy, & Frequency Analyzer; Measures the reverberant qualities of acoustical spaces for digital reverbs.
Reverb Program Select Control
Chooses which algorithm will be operating in a digital reverb.
Reverb Time Control
Controls how long the reverb will last.
Reverb Diffusion Control
Describes how dense or thin reverb will sound by adjusting the number of reflections heard within the reverb.
Reverb Pre-Delay Control
Allows a period of time to elapse before the reverb begins, helping create the illusion of a very large space.
Reverb Frequency Control
Alters reverb characteristics with the EQ and filtering circuits built into the unit; Can have a dramatic effect on the reverb, brightening or damping a specific space.
Reverb Early Reflection Control
Creates the impression of a near boundary; Often called pre-echo.
Allow the pitch and timing of signals to be altered by modulating the sampling rate up or down; Frequently used to create the illusion of more sound sources than are actually present, or to correct and/or disguise slight flaws in pitch (tuning).
Harmonizers control pitch (above or below target pitch) using percentage or numerical values.
Device that adds presence to a signal processed by amplifying the even order harmonic content of the signal slightly; Controls the texture and detail of the effect.
Patching Time Based Processors
Connected into signal flow in such a way that allows the effect to be "shared" among different I/O Modules (individual tracks or instruments).
Time Base Processor Paths to Stereo Bus
1.) Auxiliary Returns 2.) Channel Line Inputs 3.) Monitor Inputs
Output does not increase when signal reaches the threshold; No compression whatsoever.
Inserting noise or data onto a frequency.
Widely used for measuring the acoustic properties of instruments, measuring electro-acoustic devices, testing microphones, and performing psychoacoustic experiments; Designed to completely eliminate reflections of either sound or electromagnetic waves.
The frequency at which a high or low frequency EQ section starts to take effect. Also referred to as turnover frequency.
The rate at which a high or low frequency EQ section reduces the level above or below the cutoff frequency. Usually 6, 12, 18 or 24dB/octave.
The frequency range that is allowed through.
The frequency range that is attenuated.
A middle frequency EQ section with controls for frequency and gain.