Glossary

This page contains English words, both technical and non-technical, commonly used in audio (and on this site). It should also serve as an index to various sections of the Wiki. I hope that this page is useful to both native English speakers and others. Therefore, wherever possible, please:

• keep all explanations in simple English
  
• include links in descriptions
  
• put entries in alphabetical order!
  

Where a topic is controversial, please make a separate page (or start a diyAudio thread?) for discussion, to avoid filling up entries with clutter.

• Amplification - The process of increasing the magnitude of a signal.
  
• Attenuation - The process of decreasing the magnitude of a signal.
  

• Baffle
  
  1. Technically, any part of an enclosure designed to stop sound waves from the rear of a driver interfering destructively with those from the front, which reduces sound output at low frequencies.
     
  2. Informally, the board on which the driver is mounted.
     
• Bass-reflex enclosure - A type of enclosure where the driver is mounted in a box containing a port (or vent). The port resonates at a low frequency (see Helmholtz Resonator), and thereby gives extended bass response compared with the equivalent sealed box.
  
• Blameless - A Blameless amp is a standardized topology (a specific arrangement of circuitry) pioneered by Douglas Self, who corrected the flaws of legacy circuits through in-depth consideration of the designs. The Blameless amp topology provides a reference whereby anyone can make a very well-spec'd amp.
  
• Bridged - Multiple amplifiers running in series to double the maximum power (quadruple the power at a specific voltage gain). Bridging two amplifiers is typically done by feeding one amplifier an inverted signal, connecting the negatives of each amplifier together, and connecting the load between the positives.
  

• CCS (or Constant Current Source) - A circuit designed to draw a specific, constant amount of current independent of the voltage applied.
  
• Complementary Pair - A pair of oppositely polarized transistors created to closely complement (but rarely match) the specifications of each other.
  
• Crossover - An electrical circuit designed to split an incoming signal into frequency bands, one for each driver in a loudspeaker system.
  

• Dampen - To reinforce material in a system in such a way as to make it less prone to resonance. May include bracing or covering with a soft material.
  
• Diff Amp (or Differential Amplifier) - An amplifier that only amplifies the difference between two or more input signals. See also Long Tail Pair or LTP.
  
• Driver - A loudspeaker unit: the part consisting of a motor and a cone (etc) i.e. not including the enclosure . See LoudspeakerAnatomy.
  
• DSP - Short for Digital Signal Processor; provided functions to modify input signals, digitally, before amplification
  
• Dynamic - When applied to a transducer, means that movement is converted to or from an electrical signal by the action of a current-carrying wire in a magnetic field. Opposite of electrostatic.
  

• Enclosure - The box in which one or more drivers are placed to make a complete loudspeaker.
  
• Electrostatic -
  
  1. When applied to a transducer, means that movement is converted to or from an electrical signal by electrostatic attraction or repulsion between two charged conductors. Opposite of dynamic. See Electrostatic Loudspeakers.
     

• Filter, passive
  
  
  1. A circuit made up of passive components (not requiring an external power source) such as resistors, capacitors and/or inductors to change frequency response, phase response, or other characteristics of a given signal.
     
• Filter, active
  

1. A circuit made up of active components (requiring an external power source) in order to change frequency response, phase response, or other characteristics of a given signal.
   

• Frequency - in general terms, the frequency is the number of times that a given even occurs per second (measured in Hertz, aka Hz). Sound waves, which oscillate at a given 'frequency' are interpreted as sound by the human ear/brain.
  

• Helmholtz Resonator - A vessel containing air with an open neck or hole will have a resonant frequency, with the air inside it acting as a gas spring; this is a Helmholtz resonator. The resonant frequency depends on the volume of air and the dimensions of the hole. [Click Here for a useful page on the topic].
  
• Horn - A type of enclosure where the driver is coupled to the air via a tube whose area increases along its length. See basshorn.
  

• I/V stage - <define me please>
  
• Infinite Baffle - A type of enclosure where the driver is mounted inside a sealed box. Contrast with open baffle.
  
• Input Stage - First of three amplifier subsections as defined by Lin.
  
• Interaction
  
  1. When the magnetic fields of two, or more, electronics components 'interact' with each other. In some cases, these interactions can act like a transformer, whether you intended them to or not, causing instability or noise in the circuit. (eg - squealing in a PA system or buzzing when speakers play a certain note).
     

• Labyrinth - A form of transmission line where the wave guide has been folded a number of times, to reduce the external dimensions.
  
• Lin Topology - Amplifier electronics defined as three separate subsystems: Input Stage, VAS, and Output Stage, each providing it own separately defined contribution to the whole amplifier circuit.
  
• LTP (or Long Tailed Pair) - An arrangement of tubes or transistors of the same polarity where the emitters or cathodes are connected, and the differential current is made to pass through both devices. In this arrangement, the inputs of both devices are combined subtractively to the output, rejecting changes that happen at both inputs. It is usually used as an error detector in feedback circuitry because it does not respond unless there is a difference between the inputs. Another advantage is that the drift factors (for instance temperature drift) cancel out as long as the devices match and are close to each other. A current source is required at the joined emitters to bias the devices into linear operation, hence the "tail".
  
• Loudspeaker - A device or system for turning an electrical signal into sound waves in air. See the Loudspeaker page. The term loudspeaker may refer to a driver on its own, or a complete unit consisting of driver in an enclosure. The term transducer is more usually used when the sound waves are in water, solids, etc.
  
• Load - The device connected to the output of an electrical circuit, such as a loudspeaker.
  

• Mono- See Monaural
  
• Monaural- a single channel or signal.
  
• Monoblock - Refers to an amplifier that amplifies a single audio channel. "Monoblocks" usually refers to a stereo amplifier which has been split into two separate enclosures, to keep the stereo channels fro interfering, reducing crosstalk.
  
• Monophonic- see Monaural
  

• Noise - Noise can refer to any disturbance which was not in the original signal. Examples of noise would be hiss, hum, or clicks and pops. More often in audio the term Noise is used to describe hiss, which is the type of noise added at low levels by nearly all components. Applications requiring very sensitive amplifiers, for example phono cartridges, are more at risk for adding noise because the signal is being amplified is weaker, making noise sources comparatively stronger. See also Noise Floor and Dynamic Range.
  

• Open Baffle - A type of loudspeaker which consists of the driver mounted on a baffle which is open at the rear, usually a large flat or curved board. Contrast with infinite baffle.
  
• Output Stage (or OPS or Output Section) - Third and final stage of Lin amplifier topology. Load, usually loudspeaker, is connected to the output of this stage.
  

• Pole Frequency - <define me please>
  
• Port - A hole, or length of tube, put in the wall of a bass-reflex enclosure.
  
• Preamplifier - An amplifier sometimes necessary to increase the strength of a weak source, so that later equipment can reach the necessary volume and/or dynamic range. Preamplifiers cannot drive speakers, which require a more powerful amplifier.
  

• Quasi-Complementary - <define me please>
  

• Resonance - Excitement of a material or system that results in an oscillation at the resonant frequency. Dampen the system to help with resonances.
  
• Resonant Frequency - The center frequency that when applied to a system, results in resonance. (Any given system may have several resonant frequencies)
  
• Ribbon - A type of loudspeaker in which a current is applied to a thin metal "ribbon" within a magnetic field usually created by two magnets beside the ribbon. The current creates a magnetic field from the ribbon, which will move it within the static magnetic field.
  

• Sealed Box - Same as Infinite Baffle.
  
• Solid State Amplifier - Solid state refers to devices using silicon and modern semiconductor technology. These devices, as opposed to tubes, produce more high order or high frequency distortions, which can make the impression of a sharper or more crisp sound. Solid state overdrives abruptly and sharply, which is usually obvious when it happens.
  
• Speaker - Same as loudspeaker.
  
• Stereo - The stereo concept was originally developed by Alan Blumlein, using two speakers for the purpose of reproducing the recorded acoustic environment in the home of the listener. With the advent of multi-channel and digital audio, stereo has come to be a less specific term, usually used only to describe systems employing two audio channels. It may also refer to 3D stereo video technology as used at theaters, to simulate a 3-dimensional visual space.
  

• TQWT - Tapered Quarter Wave Tube. A type of enclosure combining features of both a transmission line and a horn.
  
• Transducer - Any device which converts sound waves into electrical signals, or vice versa. See louspeaker, microphone.
  
• Transmission Line - A type of enclosure where sound waves from the rear of the driver are guided into a long, possibly tapering, tube. [Click here for a website devoted to Transmission Line speakers].
  
• Tri-mode - A tri-mode amplifier is when two channels of an amplifier are run independently for midrange/treble, but are also bridged for running a (sub)woofer. It is the same as bridging the amplifier, but you keep the midrange/tweeters on their respective channel outputs.
  
• Tweeter - A driver used to reproduce treble frequencies.
  

• VAS - Voltage Amplifier Stage. Second stage of Lin amplifier topology.
  
• Vented Box - Same as bass-reflex enclosure.
  
• Voigt Pipe - See TQWT.
  

• Woofer - A driver used to reproduce bass frequencies.
  

• XO - Abbreviation for crossover.