A measure of electrical current flow, also called “amps” for short. It literally equates to the number of electrons in a
conductor flowing past a certain point in a given amount of time. Ohms law defines current (I) as voltage (V) divided by resistance (R) with the following expression: I=V/R.
A device that increases signal. Many types of amplifiers are used in audio systems. Amplifiers typically increase voltage, current, or both.
A decrease in the level of a signal is referred to as attenuation. In some cases this is unintentional, as in the attenuation caused by using wire for signal transmission. Attenuators (circuits which attenuate a signal) may also be used to lower the level of a signal in an audio system to prevent overload and distortion.
In a crossover, a filter that passes a band or range of frequencies but sharply attenuates or rejects frequencies outside the band.
Barrier Block/Barrier Strip
A series of connections, usually screw terminals, arranged in a line to permanently connect multiple audio lines to such devices as recording equipment, mixers, or outboard gear. Also called terminal strip.
BCA (Balanced Current Amplifier) is Crown’s patented PWM (Pulse-Width Modulation) amplifier output stage topology. Also referred to as “class-I,” Crown’s BCA “switching” technology provides for high output, exceptional reliability and nearly twice the efficiency of typical amplifier designs.
A type of electrical terminal, a binding post is most commonly found as the output connector on a power amplifier, or as the connectors on a speaker cabinet. A binding post can accept banana plugs, spade lugs, bare wire and others. Generally, binding posts are color coded, with the black connection going to ground, and the red connecting to hot.
An operating mode of an amplifier that allows a single input to feed two combined output channels in order to provide a single output with twice the voltage of an individual channel in Stereo or Dual mode.
In audio terms, a Bus is a point in a circuit where many signals are brought together. For example: Most electronic items have a Ground Bus where all of a device’s individual ground paths are tied together.
A type of crossover circuit design having a flat magnitude response, in other words, no amplitude ripple in the passband.
An unwanted edgy tone containing high harmonics of 60 Hz that sometimes accompanies audio. Usually caused by grounding problems.
An electronic component that stores an electric charge. It is formed of two conductive plates separated by an insulator called a dielectric. A capacitor passes AC but blocks DC.
A resettable device intended to provide protection to electrical circuits. It opens when current flows though it that exceeds its current rating.
A specific type of distortion. If a signal is passed through an electronic device which cannot accommodate its maximum voltage or current requirements, the waveform of the signal is sometimes said to be clipped, because it looks on a scope like its peaks have been clipped off by a pair of scissors.
A compressor is a device that reduces the dynamic range of an audio signal. First a threshold is established. When the audio signal is louder than this threshold, its gain is reduced.
Constant Voltage Speaker System
(Also called Distributed Speaker System) A type of speaker system where transformers typically are used at the output of an amplifier and at each speaker in order to provide a constant voltage (most commonly 70V or 100V) that can be tapped by multiple speakers. These lines can be run great distances with less loss and can have many more speakers on them than typical high current speaker lines.
An electronic network that divides an incoming signal into two or more frequency bands.
Signal bleeding or leaking from one channel of a multi-channel device to another.
Literally, the rate of electron flow in an electrical circuit. Current is measured in Amperes (or Amps), abbreviated I. Ohms law defines current as voltage (V) divided by resistance (R) with the following expression: I=V/R.
The ratio of the rated speaker impedance to the amplifier's output impedance.
A decibel, a tenth of a bel, is used as an expression of the ratio between signal levels.
Distributed Speaker System
(Also called Constant Voltage Speaker System) A type of speaker system where transformers typically are used at the output of an amplifier and at each speaker in order to provide a constant voltage (most commonly 70V or 100V) that can be tapped by multiple speakers. These lines can be run great distances with less loss and can have many more speakers on them than typical high current speaker lines.
The dynamic range of a sound is the ratio of the strongest or loudest part, to the weakest or softest part; it is measured in dB. An orchestra may have a dynamic range of 90 dB, meaning the softest passages have 90 dB less energy than the loudest ones.
Refers to interference in audio equipment produced by the equipment or cabling picking up stray electromagnetic fields. This interference usually manifests itself as some type of hum, static, or buzz.
The adjustment of frequency response to alter tonal balance or to attenuate unwanted frequencies.
Another name for variable attenuator, volume control, or potentiometer.
In audio, the number of cycles per second of a sound wave of an audio signal, measured in hertz (Hz).
The actual span of frequencies that a device can reproduce, for example from 5 Hz to 22 kHz.
The Frequency Range versus Amplitude. In other words, at 20 Hz, a certain input signal level may produce 100 dB of output. At 1 kHz, that same input level may produce 102 dB of output. At 10 kHz, 95 dB, and so on.
A device intended to provide protection to electrical circuits. It burns open when current flows though it that exceeds its current rating.
How much an electronic circuit amplifies a signal is called its “gain.” In most specs or references gain is expressed as a decibel value. Occasionally gain may be expressed as a straight numeric ratio (a voltage gain of 4 or a power gain of 2).
In electricity, a large conducting body, such as the earth or an electric circuit connected to the earth, used as a reference zero of electrical potential.
Ground lift is a switch found on many pieces of audio equipment which disconnects audio signal ground from earth or chassis ground. Using ground lift switches is considered to be far safer than the “3-to-2 prong AC adapter” solution.
The loop formed when unbalanced components are connected together via two or more ground paths–typically the connecting-cable shield and the power ground. Ground loops cause hum and should be avoided.
Output topology consisting of four quadrants and an ungrounded power supply.
The difference between the normal operating level of a device, and the maximum level that device can pass without distortion. In general the more headroom the better.
The inverse of the time required for one complete cycle of a wave. Thus, a 10 Hz sine wave takes 1/10 of a second to complete a full cycle.
High Pass Filter
A fi lter that passes frequencies above a certain frequency and attenuates frequencies below that same frequency. It can also be called a low-cut filter.
An unwanted low-pitched tone (60 Hz and its harmonics) heard in the speakers. The sound of interference generated in audio circuits and cables by AC power wiring. Hum pickup is caused by such things as faulty grounding, poor shielding, and ground loops.
The resistance of a circuit or device to AC (alternating current). Most modern electronic audio devices have extremely high input impedances so they can be driven by very low power outputs. Impedance is measured in ohms.
The connection going into an audio device. In a mixer or mixing-console, a connector for a microphone, line-level device, or other signal source.
Intermodulation Distortion (IMD)
Nonlinear distortion that occurs when different frequencies pass through an amplifier at the same time and interact to create combinations of tones unrelated to the original sounds. IMD specifications are usually expressed as a percentage of the amplifier’s output, and the lower the percentage the better.
Input Output Comparator. This circuit compares the output signal of the amplifier with the input signal.
A dynamics processor very similar to a compressor. In fact, many compressors are capable of acting as limiters when set up properly. The primary difference is the ratio used in reducing gain. In a limiter, this ratio is set up to be as close to infinity:1 as possible.
Generally defined in the audio industry as +4 dBu (1.23 volts) for balanced “pro” gear, and .316 volts (–10 dBV) for unbalanced “semi-pro” gear.
Linear Power Supply
A power supply that converts AC mains power for use by the amplifier by means of a conventional transformer operating at the same frequency as that of the AC mains supply (usually 50 to 60 Hz).
A transducer that converts electrical energy (the signal) into acoustical energy (sound waves).
A filter that passes frequencies below a certain frequency and attenuates frequencies above that same frequency. It can also be called a high-cut filter.
The level (or voltage) of signal generated by a microphone. Typically around 2 millivolts.
A transducer or device that converts an acoustical signal (sound) into a corresponding electrical signal.
If some of the output of an amplifier is made to be out of phase, and mixed back with the amp’s input signal, it will partially cancel the input, reducing the gain of the amplifier; this is called negative feedback. But, because it contains and therefore cancels any distortion introduced by the amplifier, negative feedback also has the effect of improving the linearity of the amplifier. Negative feedback can also lower output impedance, increasing damping factor, and can sometimes be made to flatten frequency response.
Unwanted sound, such as hiss from electronics or tape. An audio signal with an irregular, non-periodic waveform.
The amount of noise generated by the device itself with no signal present, it is measured in decibels. All electronic devices will generate a certain amount of noise, even a piece of wire! Minimizing the noise floor leads to expanded dynamic range, and cleaner recordings or sound production.
Output Device Emulator Protection. ODEP is an analog computer simulation of the output device thermal impedance.
A connector in an audio device from which the signal comes and then feeds successive devices.
The distortion that occurs when an applied signal exceeds a system’s maximum input level.
As implemented in Crown amplifiers, an operating mode that allows a single input to feed two combined output channels in order to provide a single output with twice the current of an individual channel in Stereo or Dual mode.
On a graph of a sound wave or signal, the highest point in the waveform. The point of greatest voltage or sound pressure in a cycle.
A DC voltage (typically 48V) applied to pins 2 and 3 of a condenser microphone's XLR connector to power the microphone's electronics.
The measure of displacement of a time-varying waveform between an amplifier’s input and output. Expressed in degrees.
A cylindrical plug, usually 1/4-inch (6.35-mm) in diameter. An unbalanced phone plug typically has a tip for the hot signal and a sleeve for the shield or ground. A balanced phone plug typically has a tip for the hot signal, a ring for the return signal, and a sleeve for the shield or ground.
A coaxial plug with a central pin for the hot signal and a ring of pressure-fit tabs for the shield or ground. Phono plugs are used for unbalanced signals only. Also called an RCA plug or pin jack.
Stands for Programmable Input Processor. These are optional modules that can be plugged into any PIP-compatible amplifier. There are a variety of PIP modules with varying functions.
The PIP2 standard, announced in 1998, upgraded the PIP feature set and requires both 18- and 20-pin ribbon cables which mate with a PIP2-compatible amplifier using standard ribbon connectors.
Two identical signals are "in the same polarity" if they both go positive in voltage or negative in voltage at the same time. Two identical signals are "in opposite polarity" if one signal goes negative at the same time the other signal goes positive. Two signals that are in opposite polarity are 180 degrees out of phase at all frequencies. To reverse the polarity of a balanced signal, reverse the connections to XLR pins 2 and 3 in one connector only. "Polarity" is often incorrectly called "phase," but they are not the same thing.
An electronic component that is used to provide variable control over an electronic circuit.
Literally, the rate at which energy is consumed. Power is expressed in Watts, abbreviated W. In electrical circuits, power is determined by the amount of resistance (R) times the amount of current squared with the following expression:
Radio Frequency Interference (RFI)
Radio-frequency electromagnetic waves induced in audio cables or equipment, causing various noises in the audio signal.
Removable Terminal Block (Buchanan®, Phoenix)
A series of screw terminal connections arranged in a line on a removable connector. Often found in three-terminal and four-terminal versions in audio applications. Often referred to by their brand name, such as “Buchanan®” and “Phoenix.”
The opposition of a circuit to a flow of direct current. Resistance is measured in ohms. The symbol Ω (omega) is often used to represent resistance. Ohms law defines resistance as voltage (V) divided by current (I) with the following expression: R=V/I.
An electronic component that opposes current flow.
The minimum amount of input signal required to drive a device to its rated output level.
In electronic terms, a shield is a conductive enclosure, protecting its contents from magnetic and electrostatic fields.
Signal-To-Noise Ratio (S/N)
The ratio in decibels between signal voltage and noise voltage. An audio component with a high S/N has little background noise accompanying the signal; a component with a low S/N is noisy.
A wave following the equation y = sin x, where x is degrees and y is voltage or sound pressure level. The waveform of a single frequency. The waveform of a pure tone without harmonics.
An unbalanced line (see Unbalanced).
The ability of a piece of audio equipment to reproduce fast changes in amplitude. Measured in volts per microsecond. Slew rates in amplifiers are often limited to useful levels to provide protection to the amplifier from Radio-Frequency Interference (RFI).
Sound Pressure Level (SPL)
The acoustic volume or perceived loudness of sound, measured in decibels. SPL is a function of a signal’s amplitude.
A type (and brand) of multi-pin connector developed by Neutrik® which is now commonly found on speakers and amplifiers intended to be used in high power mobile applications.
An operating mode of an amplifier that allows channels of the amplifier to function independently.
Switching Power Supply
A power supply that first converts AC mains power to a much higher frequency by means of a switching circuit before making the power available for use within the amplifier.
Energy not converted to the output of an amplifier is instead dissipated by the amplifier as heat.
Refers to a series of specifications for surround sound systems. Professional THX is used in commercial movie theaters.
Thermal Limit Control, used in some Crown amplifiers to provide the amp thermal protection.
Total Harmonic Distortion (THD)
The ratio of the power of the fundamental frequency at the output of a device versus the total power of all the harmonics in the frequency band at the output of the device. THD represents the sum of all the harmonics added by a device as a percentage of the level of the signal being measured.
A device consisting of two or more coils of wire wound on a common core of magnetically permeable material. Transformers are used in power supplies, distributed speaker systems, and are often used to provide electrical isolation in circuits to prevent ground loops because they pass AC voltages and block DC voltages.
A non-repeating waveform, usually of much higher level than the surrounding sounds or average level. Good examples of transients include the attack of many percussion instruments, the “pluck” or attack part of a guitar note, consonants in human speech (i.e. “T”), and so on. Due to their higher-than-average level and fleeting nature, transients are difficult to record and reproduce, eating up precious headroom, and often resulting in overload distortion.
Found on most mixers, trim controls provide the initial level setting for each channel’s input gain. In most cases, trim adjusts gain of the microphone preamp, but it may also apply to line level signals.
In electronics, a condition where the two legs of the circuit are not equal or opposite with respect to ground, usually because one leg is kept at ground potential. In other words: An audio signal requires two wires or conductors to function. In an unbalanced situation, one of those conductors is used to carry both signal and ground (shield). Unbalanced circuits are much more susceptible to induced noise problems than their balanced counterparts.
A device or setting which does not change signal level (does not amplify or attenuate a signal) is said to be at “unity gain.” Many processors are set up for unity gain; that is, they can be plugged into a system without changing its overall levels. In practice, unity gain is often a desired setting for maintaining gain staging, and for optimizing operating levels and signal to noise ratios.
The electrical potential between two relative points in a circuit. Voltage is measured in volts (V). Ohms law defines voltage as the product of current (I) and Resistance (R) with the following expression: V=I*R.
Power is measured in Watts, and the watt has become a common term in audio to describe the power handling capabilities
and/or requirements of speakers, and the power delivery capabilities of amplifiers. Watts law defines power (P) as voltage (V) times current
(I) with the following expression: P=V*I.
Also called Cannon, or Three-Pin Connector. A three-pin professional audio connector used for balanced mic and line level signals. The name XLR was trademarked by Cannon (now owned by ITT).
A single cable that divides into two cables in parallel to feed one signal to two destinations.