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Glossary of  Terms

Acoustic suspension:  A type of woofer system in which most of the cone's restoring force is supplied by the air confined in a sealed enclosure, rather than by the stiffness of the woofer cone's mechanical suspension.

Active crossover: An electronic crossover which uses at least one active device for gain or buffering.

Attack:  The initial time required for a signal impulse to rise from zero to its maximum amplitude.   Components with poor attack sound 'soft'.  A system which sounds 'fast' gives the impression of extremely quick reaction time to the input signal (transient).

Audiophile:  One who enjoys experimenting with high-fidelity equipment and is likely to seek the best possible reproduction.

Balanced Circuit (balanced line):   An audio circuit in which both sides of the circuit are equal, but in opposite phase from ground potential.  When one side of the balanced line is positive in respect to ground, the other side is negative. 

          'Unbalanced' single-ended inputs and outputs are standard on all consumer audio equipment. 'Balanced' inputs/outputs are common (and usually necessary) in most commerical installations (such as recording studios and public address systems) where it is necessary to run extremely long cables.  The 'balanced line' cancels 'common-mode interference' resulting in lower noise.

Banana Plug:  A single-conductor male connector in which bowed strips of metal are compressed when it is inserted into its female socket to ensure a tight fit.  It is generally the safest and most trouble-free type of connector to connect a speaker to an amplifier. (See five-way binding post.)

Bass:  The range of frequencies below about 150 cycles which are of low pitch.  Deep bass generally refers to the frequencies below about 40 cycles.

Bass Reflex or Vented (Ducted Port) Enclosure:  A speaker enclosure with a bass port or tube designed to reverse the phase of a speaker's backwave while using it to reinforce the front wave.

Biamplification, Biamplifying:  The use of an electronic crossover to divide the frequencies which are then sent to separate power amplifiers to drive the woofers and the midranges/tweeters of a speaker system.   We believe that a state-of-the-art audio system must be 'biamplified'. (See Oasis Music System Description.)

Bi - wiring:  The use of separate cables to connect a single  amplifier to the low and high - frequency crossovers (and drivers) of a speaker system.  Bi - wiring requires separate connections to the low frequency and high frequency crossover networks and require speakers which specifically accommodate this capability.  Wright Audio generally does not recommend 'bi-wiring', due to the fact that 'biamplified' systems are so much more effective.  (Warning: Never use a vacuum tube power amplifier driven 'full-range' at its input and its speaker output connected to the passive 'high frequency crossover network' on a speaker.  There is no way for the amplifier to dissipate the 'bass power' its being fed, which will cause eventual output tube failure and probably amplifier parts damage.  Some speaker manufacturer's instructions imply or state that their speaker may be driven in this fashion.  This is usually true when using transistor amplifiers, but most speaker manufacturers do not have the use of tube amplifiers in mind when the speaker instructions are written.)

Burn - in:  An extended length of time during which the component's operating parameters have become stable and are not subject to 'drift', after which normal listening may commence.  All components, including speakers and interconnecting cables, require some operation (usually 2 or 3 hours for about 3 consecutive days) when first installed before they can begin to sound their best.  It is not unusual for the sound of a component to continue to improve over a period of several weeks of use. (Also known as a 'break-in' period.)

Cartridge:  A transducer containing a stylus which transforms mechanical movements into electrical signals for the playback of (usually) vinyl records.  A moving coil cartridge converts energy through an interaction between a movable coil of wire and a 'fixed' magnet source.  A moving magnet cartridge converts energy through an interaction between a fixed coil of wire and a movable magnet assembly.

Cathode:  The negative component of the vacuum tube serving as the source of electrons.

Cathode Bias:  A vacuum tube biasing arrangement whereby a fixed or variable resistor is placed between the cathode of the output tube(s) and 'ground' making the voltage positive on the cathode and the voltage negative on the grid (with respect to the cathode).  Generally, no user adjustment is required or possible.

Chassis:  The metal frame, or cabinet, that houses the circuitry of an electronic device. 

Coloration:  A sonic 'signature' which a component may impress upon any signal which passes through it.

Crossover Network:  A device which divides the audio frequencies into specific frequencies or bands for the individual speaker drivers (woofer, midrange, tweeter) to prevent physical damage to the drivers as well as providing frequency equalizing effects.

Cutoff frequency:  The upper (or lower) frequency limit of a band of frequencies.  It is usually defined as that frequency whose output has diminished 3dB below the median output.

Decibel:  Named after Alexander Graham Bell, one deciBel is the smallest change of volume level that is perceptible to an average listener. (1 deciBel = one tenth of a Bel.)  It is a logarithmic scale used for measuring volume change. 0 dB is the threshold of human hearing and 130 dB is the threshold of pain.

dB/octave:  The measure of the upward or downward level of volume change over a frequency response curve.

Driver:  A loudspeaker device (woofer, midrange, tweeter).

Dynamic Range:  The range of volume levels, in deciBels from the softest to the loudest, which can be reproduced by a recording or playback system.

Electronic Crossover:  An 'active' speaker crossover network designed to operate between the preamplifier and power amplifier(s), rather than between the power amplifier and the speaker drivers.  An electronic crossover provides much greater frequency crossover control and higher effective overall efficiency than 'passive' crossovers.

Five-Way Binding Post:  A cable connector which will accept 1) a  spade lug, 2) a banana plug, 3) a bare wire (usually inserted into a hole in the post), 4) a loop of bare wire twisted around the post, 5)  a headphone 'tip' plug (old-fashioned type).

Fixed Bias:  A bias voltage supplied by a separate power supply making the bias independent of the current passing through the tube (or transistor).  Earlier amplifiers had bias power supplies which were 'fixed' in their bias voltage, whereas most modern tube power amplifiers enable the user to 'adjust' this voltage to provide for output tube pair matching and to compensate for operation drift due to aging of the tubes.  We recommend this simple adjustment on our amplifiers to be accomplished every 6 months for lowest signal distortion and longest tube life.

Flat: (In regards to an audio component):  having a linear frequency response.

Fletcher-Munson Curve:  A set of frequency curves showing the degree of amplitudes which frequencies must be adjusted in order to be heard as having equal loudness.  At reduced sound levels, the ear's sensitivity to low frequencies, and to a lesser extent, high frequencies, are progressively diminished.

Frequency Response:  A rating or graph which expresses the manner in which a circuit or component handles the different frequencies falling within its operating range.

Gain:  The degree of magnification of the input signal achieved in each stage of an amplifier.

Grain:  A coarsening of the texture of reproduced sound, as of grain in a photograph.  One of the most noticable negative aspects of transistor and digital sound. (See 'Liquid'.)

Graphic Equalizer:  An active electronic device which allows the amplitude adjustment of narrow 'bands' of audio frequencies to correct primarily for recording and listening room deficiencies.

Harmonic:  A multiple of any fundamental frequency.  The fundamental is considered to be the first harmonic.   The second harmonic of 1000 cycles is 2000 cycles. The third harmonic is 3000 cycles.

Harmonic Distortion:  The addition (sometimes intentional) of spurious harmonics to a signal passing through a device.  'Single-ended' tube power amplifiers 'generate' primarily 2nd harmonic distortion on the order of several percent, which many listeners prefer, feeling that a certain 'musicality' has been restored which was lost in the recording/reproducing chain.   'Even order' distortion is considered much more musical than 'odd order' (3rd, 5th, 7th, etc.) harmonic distortion.

Hertz: (After Henrich Hertz)   Cycles per second.  Abbreviated Hz, and kHz (kilo = thousand) for 'thousand cycles'.

High Pass Filter:  A filter which passes only upper frequencies which are defined at a lower 'cutoff' frequency, and having linear response above that point.

Imaging:  That audible effect which allows the listener to place the various sounds of instruments and voices in particular points in space across the soundstage.

Impedance:  Unit of measure, given in ohms, for resistance to an alternating current. It must be matched up between audio units which are connected to each other.

Input Impedance:  The 'load' presented by a component's input to the output of the device which feeds it.

Integrated Amplifier:  The combination of the preamplifier/ control center with the power amplifier(s) on one chassis.

Intermodulation Distortion (IM):  Creates new and undesirable sounds from the interaction of two correct sounds.  

Line Level:  An audio signal level which ranges from about 0.1 (100 millivolts) to 3 volts.   All modern source devices (CD, DVD, tape players) provide 'line level' outputs. 

Linearity:  The ability of a component, or any of its parts, to reproduce every frequency at correct strength.

Line Output:  The output of a device which provides a line-level signal.

Liquid:  The complete lack of 'grain' or texture in reproduced sound.

Listening Fatigue:  A 'psycho-acoustical' condition whereby the listener of a music reproduction system becomes increasingly 'fatigued' and restless due to very small amounts of distortion which causes discomfort.

Load:  The device to which electrical energy is supplied; i.e., a speaker constitutes the load of an amplifier.

Low Impedance:  Device having a nominal impedance of 600 ohms or less.

Low Pass Filter:  A device which passes only frequencies below a certain limit (cutoff frequency) and is of equal amplitude below that frequency.

Monoblock:  A single-channel power amplifier. 

Monophonic (Mono):  Single channel (not stereo).

Passive Crossover:  A crossover network dividing the frequencies without any active amplification or buffering components and which uses only resistors, capacitors and inductors.

Pentode:  A vacuum tube type which contains five elements:  the cathode, screen grid, control grid, suppressor grid and plate.

Phase:  In acoustics, a part of the sound wave - increasing compression or rarefaction.  Two sound sources are in phase when they are both compressing the air at the same time; out of phase when one is compressing, and one rarefying.

Phasing:  The condition of the relative polarity of the plus and minus electrical signals.

Phono Plug (also known as RCA plug): The standard coaxial plug for unbalanced signal cable interconnections between components. Designed by RCA.

Power Amplifier:  The amplification device which boosts the level of a line-level signal in order to supply sufficient power to directly drive a speaker.

Power Supply:  A device which provides the voltages allowing for the operation of an active component.

Preamplifier, preamp:  A component which provides amplification of low level signals to the strength necessary for amplification by a power amplifier..  (There is no such device as a 'passive preamp').

Push-Pull:  A type of amplification circuit in which two (or more)  identical tubes or transistors each amplify in such a way that when one tube (or transistor) is operating on a positive alternation, the other operates on a negative alternation. 'Push-pull' amplifiers are able to provide much higher power output with significantly lower overall measurable distortion than 'single-ended' amplifiers.

Receiver:  A radio tuner, preamplifier/control center and power amplifier(s) all sharing the same chassis.

RIAA Curve:  The standard equalization curve used only for phono disc playback and incorporated into every preamplifier which has an input accommodating phono cartridges.  Phonograph records are (were) made with the bass frequencies attenuated and the treble frequencies accentuated. During playback, the bass must be boosted, and the treble de-emphasized.  

     Until 1954, each record company had its own way of 'distorting' the true sound, so that a number of different equalization curves are necessary to play records made before midsummer 1954.   Since then, almost all  records have been equalized to the RIAA curve.

Sensitivity:  A measure of the amount of signal input level a device requires in order to produce a certain output level.  In reference to speaker specifications, the sound pressure level measured at 1 meter at 1 watt of signal level, usually taken as an 'average' across most of the frequency range of the speaker.  The more sensitive a speaker system is, the higher is its efficiency at transforming electrical energy to physical energy, and thus a lower power output amplifier is required. 

       Speaker systems may also be too efficient for a smaller room by reproducing system electrical noise in the form of 'hiss', 'hum' or other noise which may be heard especially if one is forced to sit, due to room size, too close to the speaker.  Also, the volume control may become very sensitive or 'touchy' at the lowest end of its scale.

Signal Processor:  Any device which allows the user modification of the program signal.

State - Of - The - Art:  The best sound quality technically obtainable, regardless of cost.

Subwoofer:  A woofer and enclosure system which is physically separate from the main speaker system and (as originally defined) intended to reproduce sound only below 50 cycles.  This definition has 'loosened' in recent years to mean a woofer  system reproducing sound below about 100 cycles. Despite marketing hype from 'subwoofer - satellite' manufacturers, bass is NOT omnidirectional (nor is it reproduced properly in monaural) below 100 cycles.

THD:  Total harmonic distortion which is a measure of the sum of all the harmonics produced by an active component due to its nonlinearity expressed as a percentage of the fundamental signal.

Transient Response:  The ability of a component to react instantly to the start or the end of a recorded sound.

Transmission Line Enclosure:  A type of woofer loading in which the rear of the cone works into the weight of the volume of air in a long, usually tapered and open-ended tube.  The only enclosure design which does not 'reflect' its own 'box sound' back through the thin cone of the woofer, therefore providing a smooth 'boxless' sound.

Triode:  A vacuum tube containing three elements: cathode, control grid and plate, the basic amplification tube in almost every amplifier.

Tuner:  A radio receiving circuit without the preamplifier or power amplifier.

Turnover  frequency:  The frequency at which an equalizer or filter control changes the incoming frequency by 3 dB.

Tweeter:  A speaker designed to recreate high-frequency sounds only.

Ultra-linear:  This was originally a proprietary term (by Hafler and Keroes) which described a circuit whereby a tube output transformer was used providing taps on its primary winding at a certain percentage from the center tap to the plate end.  This enabled tetrodes and pentodes to provide most of the power output of which those tube types are capable, while providing the lowered distortion of triode operation.

Unbalanced:  A signal carried between the ground and a single conductor (single-ended).  Also describes a neurotic audiophile.

Woofer:  Usually described as the largest driver in any speaker system, regardless of its size.   Strictly speaking, a speaker driver designed only for the reproduction of low frequencies.

XLR  Connector:  The standard connector used for balanced - line interconnecting signal cables.


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