Random Play
Also known as shuffle play. In CD players and changers, this function randomizes the order of selections during playback. Some CD players offer a "Random Play with Delete" feature that prevents a piece from being repeated once it has been played. |
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Range Audio
Usually described as frequency range, this is a system's frequency transmission limits, beyond which the frequency is attenuated below a specified tolerance. Also, the frequency band or bands within which a receiver or component is designed to operate. |
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Rarefaction
A state or region of minimum pressure in a medium traversed by compressional waves (sound waves).
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RDS
Radio Data System tuners can automatically tune in stations according to the types of music (or talk) they broadcast. R D S also enables a receiver to display text messages and even graphics (usually call letters and format information) that many FM stations include on a sub carrier signal within their normal broadcast signal. Some R D S equipped tuners can even override with traffic alerts or emergency broadcasts, during playback of other media - CD MD, or cassette. There are other useful features too, many of which are offered by the growing number of R D S stations. |
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Re
The DC resistance of a speaker voice coil.
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Reactance
In Ac circuits, whether passive or active, a form of frequency dependent resistance produced by inductors. Such an inductive loading will allow all dc current to pass without change, but will attenuate various, mostly higher frequencies, depending on the nature of the coil. |
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Receiver
A device designed to receive a signal or command from a source such as a transmitter.
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Rectification
A conversion of Alternation Current (AC) into Direct Current (DC) by means of a rectifier.
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Relay
An electromagnetic switch that allows small, relatively low level signals to operate higher amperage devices. Also used when polarity reversal ins necessary.
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Remote
A common name for the remote control transmitter used with a remote security system (Also see Transmitter).
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Remote Control
For remote-compatible devices, wired or infrared wireless remotes are either included with a receiver or CD player, or available as accessories. This enables the unit to be operated from the back seat or even outside the parked car. |
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Remote Out
A "turn on signal" source for amplifiers and signal processors.
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Remote Wire
The cable connected between the amplifier and the receiver that turns on the amplifier whenever the receiver is on. The receiver's connection supplies a 12 volt signal only, that may be used simultaneously to turn on such devices as an equalizer, amplifier, and to raise the antenna. |
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Reset
The ability of a security system to automatically stop sounding the siren and return to an armed state after being triggered, as long as no further trigger conditions are present. |
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Resistance
The electrical term used to describe the property that various materials possess to restrict or inhibit the flow of electricity. Electrical resistance is relatively low in most metals and relatively high in most nonmetallic substances. Electrical resistance is measured in ohms.
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Resonance
The term used to describe the tendency of objects to vibrate at certain frequencies. This can be a useful or undesirable effect, as in planned enclosure or driver resonance, or as in unplanned enclosure resonance or wall resonance. |
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Resonant Frequency
The frequency at which a speaker cone vibrates the easiest-the point at which it has the most amplitude.
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RF
Radio Frequency - An alternating current or voltage with a frequency above about 100kHz. It's called radio frequency because these frequencies are radiated as electromagnetic waves by radio ( and now television) stations.
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RF Modulator
A device that converts a signal (typically audio and/or video) into a radio frequency.1
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RF Package
An add-on audio system comprised of a CD or MD changer, a CD controller, and an RF modulator. Used to add CD or MD playback ability to virtually any car radio.
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RGB Transfer
Video signal broken down into separate Red, Green and Blue components, and transferred as such.
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Rigitex Woofer Cones
This cone is made of polypropylene and has stiffening rubs allowing the cone to be lighter. The result is increased efficiency making it an ideal cone material for speakers that will be driven by a factory head unit.
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Ripple-Amplifier
A train of pulses that occurs when AC is changed to DC via a rectifier. These pulses are left on the DC.
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Ripple-Speaker
The maximum deviation from flat response, measured in decibels-it indicates the port's effect on woofer output.
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Rip Stop Spiders
Spiders made of high strength synthetic (often aramid based) materials that are resistant to tearing.
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RMS
Root Mean Square - The square root of the mean of the sum of the squares. Commonly used as the effective value of measuring a sine wave's electrical power. A standard in amplifier measurements.
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Roll-Off
Relates to the attenuation of frequencies, above or below a given point, at a specific rate.
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Roof-Mount Antenna
A permanently-installed antenna located in the center of the vehicle's roof.
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Room Response
The effectiveness of any speaker system is a function of the room or environment in which it is played. The coupling of the speaker to the room or listening space is a function that is as critical as that between the woofer and the enclosure. When in doubt, experiment! This is the only practical method of achieving the optimal response form speakers in nearly any situation. Of course, computer modeling based on real time measurements could be substituted, albeit quite expensively. |
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Rotary Commander
Also called driver's remote. An ancillary control interface providing intuitive and safe operation of a car stereo by keeping your eyes on the road.
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Rotary Encoder
A digital control which emulates the function of a "big round volume knob". Also controls additional preamp functions.
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Rotary Lever
A control arm providing easy access to the Seek and AMS functions, positioned beside the rotary encoder.
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Rotary Scan Head
A magnetic pick-up head, typically used in VCR's and DAT machines, which spins as it reads the information from the tape. Higher signal density is possible, providing more accuracy in recording and playback.
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Rotary Volume
An analog or linear volume control operated with a knob to raise and lower the volume, as opposed to separate digital "up and down" pushbuttons or pushbar. |
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