Here is my 2 cents..... I tried not to duplicate items already described with an exception where I felt needed....I just assorted them from
http://www.carstereo.com and another good and rich source can be
http://www.lightav.com/car/glossary.html Acoustic absorption: The sound deadening (absorptive) characteristics of any substance. The reference unit of absorption is one sabine which is equal to the sound "absorbed" by a one square foot opening through which sound passes (open hole).
Amplification: Increase in signal level, amplitude or magnitude.
Amplifier: A device which increases the level of a signal (by increasing the voltage or current). Some amplifiers are used to isolate or control a signal, and may not increase level -or may actually decrease the level (line out converter, head amp).
Analog: An electrical signal whose frequency and level vary continuously in direct relationship to the original acoustical sound waves. "analog" also may refer to a control or circuit which continuously changes the level of a signal in a direct relationship to the control setting.
Attenuator: Used decreasing the strength of a signal.
Bandwidth: Refers to the "space" in the frequency response of a device through which audio signals can pass (between lower and upper frequency limits, those points where the signal level has rolled off 3 db).
Bi-amplification: A stereo, or amplifier, that is "bi-amped" uses separate power amplifiers for the woofers and the mid-range/tweeters in a speaker system. In a bi-amped system, the audio signal from the radio or tape is passed to an electronic crossover which divides the signal into bass and mid-range/treble signals. Each of these signals is then sent to its own independent amplifier and speakers. Bi-amplification offers the advantage of more sound with fewer watts, less phase error due to elimination of passive crossover. Two 5-watt amps can play louder with less distortion than a single 10-watt amp, used conventionally, and since each such amp has only part of the music to handle, it can do its job with less distortion. Bi-amplification also gives you a more precise bass and tone control.
Capacitor: A component used in crossover filters that creates frequency dependent impedance (higher at low frequencies and lower at high frequencies - the opposite of what an inductor creates).
Clipping: Occurs when the continuous power to peak power capabilities (headroom) of an amplifier are exceeded. The result is very audible distortion, also visible on an oscilloscope.
Crossover frequencies: The frequencies at which a passive or electronic crossover network divide the audio signals -which are then routed to the appropriate speakers. Crossover frequencies are expressed in hertz (hz).
Crossover network: A unit which divides the audio spectrum into two or more frequency bands.
Crosstalk (channel separation): Crosstalk is the amount of signal that leaks from one stereo channel into the other, or from one tape track into another. It is expressed in decibels, with the higher the value the better. Channel to channel crosstalk should be at least 30 db, with 40 db being very good.
db: The "db" (decibel) is a unit of measurement for ratios of sound level, power, voltage, and other quantities. The db is only meaningful when referenced to some actual value (e.g., speaker output: 93 db at one meter with 1 watt of input power).
db SPL: SPL is sound pressure level (i.e., an acoustical measurement). One db spl is the smallest audible difference in sound level. 0 db spl is 0.0002 dynes/square centimeter or 20 micro-pascals. It is also the threshold of human hearing at 1 khz (the threshold of pain is between 120 and 130 db spl).
Directionality: Speakers radiate their sound in an angle that becomes narrower and narrower as the sound frequency becomes higher. Therefore, a tweeter is very directional, and a bass woofer is very non-directional.
Dispersion: Dispersion is another word for distribution of sound. The bass tones of a speaker are basically non-directional, and in a car, fill-up space. Treble, or high sounds, are very directional.
Distortion: Sound which is modified or changed in some way is called distortion. It can be caused by equipment which doesn't faithfully reproduce the original input signal. The percentage of distortion is a measure of the amount of signal change produced by a component. Any good amplifier states its power in terms of RMS (root mean square), or continuous power. That is, how much power it puts out continuously with a minimum of unwanted noise, or total harmonic distortion (THD). Many amplifiers list their power in peak terms, or how much power the amp will put out in a peak burst, but not hold continuously. Such amps generally have a high distortion figure, if shown at all. In a speaker, distortion is produced by several things, most related to poor construction. For example, poor alignment of the voice coil in the magnet gap can cause uncontrolled vibrations of the cone. Voice coil rubbing is the most common cause of speaker distortion, generally caused by being overdriven.
Dolby noise reduction: Dolby is a special, patented, noise reduction system that increases dynamic range of Dolby encoded broadcasts and decreases background hiss by about 10 db. Dolby encoded tapes are recommended because of superior signal- to-noise ratio, and increased dynamic range.
Driver: Another name for a loudspeaker; usually the term is used when the loudspeaker is coupled to a "horn" for acoustic coupling and controlled dispersion of sound.
Dynamic range: The difference, in decibels, between the loudest and the quietest portions of a musical performance (or between the maximum signal level and the noise floor of electronic equipment).
Electrostatic speaker: A speaker which uses two pieces of metallic foil separated by a sheet of dielectric (as opposed to the cone and voice coil assembly on a cone-type speaker). A constant voltage is applied to the foils to maintain a steady attraction between them. As a music signal is superimposed over the constant voltage, the foil moves much in the same way that a speaker cone moves. The movement of the foil causes a disturbance of the air which in turn generates sound waves.
Equalizer (graphic): A graphic equalizer is a sophisticated frequency control device. It can come with the dual function of being an external amplifier, or it can be passive, used as a pre-amp. Equalizers divide the frequency range into several sections, from low bass sounds to high treble sounds, with each control allowing a plus or minus range of 12 db. With an equalizer you have the ability to tune your car sound to your listening preference.
Fader: A fader is a control that allows you to balance the sound in a four-speaker system from front to rear. When used with a balance control, you can adjust the sound level from front to rear, and from right to left.
Frequency: The rapidity of change in current or voltage in an electrical signal or of air pressure in an acoustical (sound) signal. Frequency is measured in cycles per second; 1 cycle per second (cps) is 1 hertz (hz). The higher a note on the musical scale, the higher its frequency.
Ground loop: Caused when multiple grounding points are used in a multi component system. Many stray electrical currents are flowing through the car chassis, as a result of the grounding of different electrical components in the car. If both ends of a braided shield are grounded, or if multi-component systems are grounded independently, electrical currents in the vicinity of the ground connections will take the path of least resistance to the other end, which is over the shield (or audio cables) rather than through the higher resistance of the ground. When an electrical current flows through a conductor (the braided shield or audio cables in this case), magnetic forces expand and contract around the conductor. This is the condition that exists when multiple grounding points are used. This induced current is what causes the noise on a system (generally seen as high-frequency oscillations on an oscilloscope).
Hertz: A unit of measurement for frequency, equal to one cycle per second. Named after the physicist H.R. Hertz. Commonly abbreviated Hz.
High level crossover network (passive): A crossover network designed to operate at high levels and which is placed between the power amplifier and the loudspeakers (the type of crossover normally built into a speaker system).
Impedance: Opposition to the flow of an alternating current (music is one form of alternating current). Although impedance and resistance share the same unit of measurement, the Ohm, they are not the same thing. In an electrodynamic speaker, the impedance varies with the frequency of the signal being applied to it.
Inductor: An inductor is a coil of wire used in crossover filters that creates a frequency dependent impedance (lower at low frequencies and higher at high frequencies - the opposite of a what a capacitor creates).
Input sensitivity control: Adjusts the input power (expressed in millivolts, or volt) to reduce distortion.
Intermodulation distortion (in loudspeakers): Is generated in single cone speakers when the cone is reproducing a high and a low frequency simultaneously. If the low frequency is distorted in any way, it will distort the high frequencies by flattening off the peaks.
Loudness contour: The human ear does not hear low frequencies well at low volume levels. Therefore, a loudness control boosts, or enriches the low bass sounds when the volume is turned down. Should not be used at high volume listening levels.
Loudspeaker: An electroacoustic transducer that converts electrical audio signals at its input to audible sound waves at its output. May be the same as "speaker". In a multiple driver system, the term "loudspeaker" may refer to a given driver whereas the term "speaker" may refer to the overall system, including all drivers, crossover network and the enclosure.
Loudspeaker compliance: It is the acoustical and mechanical equivalent of capacitance. Determines how easily a speaker cone/voice coil assembly will move when an electrical signal is applied to it.
Low level crossover network: A crossover network designed to operate at line levels and which is placed before the power amplifier(s); used in bi- or tri-amplified speaker systems. May be electronic crossover.
Mute switch: This feature cuts out the annoying hiss between stations. If you manually change stations it will sound a lot cleaner when the switch is on. With the mute switch off it will let in the noise, but also allow you to hear distant or weak stations
Ohm: A unit of measurement for resistance and impedance. Represented by the symbol which is the Greek letter Omega.
Phase: Phase describes the relative position of two sound waves with respect to one another, usually measured in degrees. One complete cycle of a sine wave is considered to be 360°, 1/2-cycle 180°, etc.
Piezo electric tweeter: A very efficient, highly sensitive, highly directional tweeter which operates without a magnet or crossover.
Pink noise: A sound which contains all frequencies perceptible to the human ear. Is used in the equalization of systems.
Power handling capability: In speaker systems, the maximum amount of power that can be safely accommodated without damage. The power handling capacity will vary depending on the frequency and length of time the signal is applied.
Pre-amp: A pre-amp includes all of the controls for regulating tone, volume, and channel balance. It is a circuit unit which takes a small signal and amplifies it sufficiently to be fed into the power amplifier for further amplification.
Pre-amp fader: This circuitry provides an effective level control between two amplifiers, built-in and external without loss of power.
Resistance: The opposition to the flow of D.C. current measured in OHMS.
Resistor: A device used to restrict the flow of current in a circuit.
Sensitivity (loudspeaker sensitivity): The sound pressure level a speaker produces when fed by a given input power, measured at a specified distance on-axis (directly in front of the speaker). Usually specified in db spl at 1 meter, 4 feet or 30 feet, and with a 1 watt or 1 milli-watt input signal.
Signal- to-noise ratio (SIN): This figure specifies, in decibels, how quiet and hiss-free the background will be in relation to the music, with a good signal. A rating of 60 db, for example, means that the signal is 1,000 times stronger than the noise.
SPL (sound pressure level): An acoustic measurement of the sound energy, usually measured in db spl (see "db spl"). Not the saml as loudness, which involves subjective measurement based on the human ear's differing sensitivity at different frequencies and levels.
SubWoofer: A loudspeaker made specifically to reproduce the lowest of audio frequencies, approximately between 20 hz and 125 hz (the higher limit is flexible and there is no rule of thumb for it).
Voice coil: A coil of wire wrapped around a tube (coil form) attached to the speaker cone or driver diaphragm. The coil becomes an electromagnet when an audio signal is applied; this interacts with a permanent magnet and causes the cone or diaphragm to vibrate.
A coil of wire inside the speaker which is attached to the bobbin. When an audio signal flows through this, it causes the speaker cone to move forward/backward (because a speaker is an electromagnetic device).
Watt: A unit of measure for electrical or acoustical power. Also used to measure different other things.
22nd June 2006, 16:24
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