Dynamic Processing Flashcards
AGC
automatic gain control; sets the amplification of the carrier frequency to an appropriate value, can “lock onto” the input signal such that gradual changes in input amplitude will have minimal effect on the output; however, cannot instantaneously adapt to rapid changes; extremely fast response time is not desirable because this would make the AGC circuit overly sensitive to noise or to intentional variations in the amplitude of the input signal (i.e., amplitude modulation)
Attack time
refers to how quickly a signal is attenuated by a desired ratio by 60 percent in a dynamics processor
Attenuation
reduction in the level of an audio signal
Breathing (pumping)
continuous dynamic movement of a signal due to a dynamics processor; compressor engaging and releasing causes a fluid push and pull
Brickwall limiter
type of downward compressor which is set to a very high ratio(often infinity: 1 or 100:1), and does not allow any signal to pass above a given threshold; often used to prevent digital distortion or overages
Ceiling
threshold of a limiter; highest point which a signal can pass through, it defines the maximum level (in dB) that the limiter will allow the signal to output
Center image shifting
process of adding phase de-correlated signal into a stereo signal which causes a mono signal to be shifted to sounding more “stereo” or “wider”
Companding
the process of compressing an audio signal prior to transmission and expanding it after reception; a contraction of the words compressor and expander, which describe contrary dynamics processors; compressor is employed to reduce the dynamic range of a signal, while an expander increases the dynamic range
in a wireless microphone system, compression takes place in the transmitter, while expansion occurs in the receiver; both the compression and expansion are performed by a voltage-controlled-amplifier (VCA)
Compression
the act of dynamically controlling a signal by increasing or decreasing the signal above or below a given threshold; main goal is to make a signal more dynamically consistent
Compressor
a type of dynamics processor that increases or decreases the amplitude of a signal above or below a given threshold
Downward compressor
compressor which attenuates a signal above a set threshold
DC voltage
DC electrical signal used to manipulate the values of components in analog circuits; in a mixer and other audio circuits that use a voltage-controlled amplifier (VCA), a DC voltage can be used to set the gain of the VCA
applicable for things like compressors and gates, where the DC voltage may either be a signal proportional to the audio level the devices are acting upon, or could be from some other source
DCA
digitally-controlled amplifier; variable-gain amplifier that is digitally controlled through binary numbers; uses a stepped approach giving the circuit graduated increments of gain selection
De-esser
type of dynamic EQ which is meant to attenuate high-frequencies (above 1K)
Detector
part of a dynamics processor that identifies whether a signal is above or below a set threshold and sends signal to a gain unit; senses the current audio level and sends control signals to a gain cell to tell it when and how it needs to act on the signal
Detection path
section of a signal chain in a dynamics processor that sends signal to the detector and out to the gain unit
Downward expansion
type of dynamics processing where signal below a set threshold is attenuated to by a given ratio
Ducking
type of downward compression which attenuates a signal but the compressor is side-chained to an alternate signal; ex. bass being dynamically attenuated to the signal of a kick drum
Dynamics
broad term referring to the amplitude range of a waveform
Dynamic range
the range between the highest and lowest amplitude signals of a waveform
Electro-optical
gain reduction is achieved through the use of special light dependent resistors optically coupled to an electro-luminescent panel; another method uses LEDs to illuminate the photo-resistor; produces a particularly smooth and natural sounding gain reduction (LA-2A)
Envelope
refers to the dynamic ADSR of a signal, or compressor; in a compressor the attack and release functions determine the envelope of a signal
Envelope follower
device used in musical electronic environments that detects the amplitude variation over time in an incoming signal and produces a control signal that resembles it; usually offers the possibility to modify the attack and the release stages of the input signal
Expander
type of dynamics processor where signal above or below a set threshold is attenuated or increased by a given ratio, but its main goal is to increase the dynamic range of a signal
Fade
gradual decrease or increase of the level of an audio signal
Fade-in
gradual increase in level of an audio signal
Fade-out
gradual decrease in level of an audio signal
Fader
a device for gradually increasing or decreasing the level of an audio signal
Fader riding
manually automating the level of an audio signal by controlling it with a fader
Frequency dependent dynamic processing
processing that is implemented by dynamic EQs where dynamics are applied to specific frequency ranges
Gain range
range by which audio can be boosted or attenuated
Gain reduction
regulation of the amplitude of a signal in order to prevent it from getting too loud, or to keep the signal at a relatively uniform level, or both
Gain before threshold
gain applied to a signal before signal attenuation (1176)
Gate
type of downward expander that has a very high ratio, intended to decrease lower signals; also called noise gate
Hole-punching
a sudden audible drop in level after a program transient
Chatter
a rapid opening and closing of a gate, causing audible distortion
Hold
sustain value of a dynamics processor which occurs before the release stage of ADSR values; often seen in expanders to keep gates open for a certain amount of time before the release
Key input
sidechain input signal of a dynamics processor; when a signal is “keyed” it is sidechained to (x) signal
Keying
sidechaining the detector of a dynamics processor to a alternate signal, then applying dynamics processing on a different signal (that which is being keyed)
Knee
threshold-determined point where the ratio changes
from unity gain to the set ratio
Hard knee
threshold sets a strict limit between no treatment and full treatment
Soft knee
enables smoother transition between no treatment and treatment—gain reduction starts somewhere below the threshold with diminutive ratio, and the full compression ratio is reached somewhere above the threshold
Leveler
device which uses an audio gain circuit to increase or decrease the level of audio passing through it based on parameters set by the user; goal is to have an audio signal stay at roughly the same volume for an extended period of time
Link
connects the attack and release time on a dynamics processor; also can link stereo compressors to compress with the same settings on both channels of stereo
Limiter
downward compressor with a ratio set to 10:1 or higher
Look ahead
allows side-chain to see the input signal slightly in advance so it has more time to react to transients
Loudness
subjective attribute of level; something is perceived as louder if the dynamic range is smaller
Makeup gain
a feature on dynamic processors that allows the user to turn up the overall signal after the audio has been compressed
Microsecond
one millionth of a second
Millisecond
one thousandth of a second
Multiband compressor
splits the input signal into different bands, then lets us compress each band individually
Multichannel processing
a processor that takes in the outputs of multiple different audio signals (usually stereo) and outputs the processed signal
Mute
button found on some recording consoles that, when pressed, silences the input or other signal it is associated with
Normalize
to boost the highest sample of a digital sound file to the maximum amplitude the system is capable of encoding, short of clipping (0dBFS), and then raising all other samples by the same proportion
Optical compressor
side-chain controls the brightness of a bulb or LED; on the gain stage, there is a photo-resistive material, which affects the amount of applied
gain; exhibit the slowest response times of all compressors
Vari-mu
no ratio, incremental amount of gain reduction with relation to input levels up to a point where the compressor becomes linear
Parallel compression
take a copy of a signal, compress it, and blend the compressed version with the uncompressed original
Perceived loudness
human perception of sound intensity
Peak limiter
special type of compressor that prevents the signal from exceeding a certain preset level, no matter what the input signal level may be
Bus compression
engaging a compressor on the mix bus while mixing
Program dependent processing
rather than responding to a fixed value, the attack and release times (and ratio in the case of the LA-2A) of a compressor vary somewhat depending on the frequency and amplitude of the incoming signal
Ratio
determines the extent to which overshooting signals are reduced toward the threshold
Release
determines how quickly gain reduction falls
Rise time
time required for a device to allow a signal waveform to rise from 10% of maximum amplitude to 90% of maximum amplitude, usually measured in microseconds
Sidechain
control input used to trigger a compressor or gate with an external signal
Skirt
slope of a filter response curve outside its passband
Soft limiting
applying a soft knee type of process to a limiter
Stereo link
ensures that both left and right channels are processed identically, so no image shifting occurs
Tape compression
recording at high levels to analog tape; way it reshapes the amplitude detail of an audio waveform comes from a kind of low-threshold, variable-ratio compression with infinitely fast attack and release, meaning no compressor can accurately mimic it
Threshold
divides the full input level range into two sections; depending on the processor, the treated level range might be above or below the threshold
