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1. Radio Data System (RDS):RDS stands for Radio Data System. RDS tuners can automatically tune in stations according to the types of music (or talk) they broadcast. RDS also enables a receiver to display text messages and even graphics (usually call letters and format information) that many FM stations include on a subcarrier signal within their normal broadcast signal. Some RDS 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 RDS stations
Submitted on Thursday, April 29, 2010 5:55:25 PM

2. Radio Frequency (RF)
An alternating current or voltage with a frequency (or carrier wave) above about 100kHz. It's called radio frequency because these frequencies have a capacity to be radiated as electromagnetic waves by radio ( and television) stations.
Submitted on Tuesday, June 30, 2009 5:55:25 PM

3. Radio-frequency interference (RFI):
Radio-frequency sound waves can be caused by many sources including; shortwave radio equipment, household electrical line, computers and many other electronic devices. RFI sometimes interferes with audio signals, causing noise and other distortions.
Submitted on Tuesday, January 26, 2010 5:55:25 PM

4. Random Code Encryption
(or Varicode2 Transmitting System) In auto security systems, these terms describe anti-code grabbing technology, a feature which prevents malicious persons who use a special receiver to intercept remote control codes, from using it to defeat the alarm.
Submitted on Sunday, April 25, 2010 5:55:25 PM

5. 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.
Submitted on Monday, December 14, 2009 5:55:25 PM

6. Range (Audio)
Definition: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.
Submitted on Sunday, April 05, 2009 5:55:25 PM

7. Rarefaction
Definition:In sound waves, the opposite of compression. An area of decreased air pressure caused by a sound wave. In a graphical depiction of a cyclical waveform rarefaction occurs when the wave is in the bottom segment. Sound is simply the alternating compression and rarefaction of air at varying and often overlapping frequencies, within a range to which humans are sensitive.
Submitted on Tuesday, December 22, 2009 5:55:25 PM

8. Ratio-One of the parameters which can be varied on dynamic range processors such as compressors and expanders. It represents the compression or expansion ratio between input and output levels. A compressor with a 2
Submitted on Tuesday, January 27, 2009 5:55:25 PM

9. RCA Connector-"Phono" plugs, used primarily as low-level connections between Phonographs/CD players/Tuners/Recievers/Amplifiers
Submitted on Friday, November 07, 2008 5:55:25 PM

10. RCA jacks:
The coaxial connectors commonly used to interlink components in the world of car audio. (e.g., My AM/FM/CD player has four RCA jacks that send the signal on to my four channel amplifier.)
Submitted on Saturday, January 10, 2009 5:55:25 PM

11. RCA jacks-The coaxial connectors commonly used to interlink components in the world of car audio. (e.g., My AM/FM/CD player has four RCA jacks that send the signal on to my four channel amplifier.)
Submitted on Tuesday, August 10, 2010 5:55:25 PM

12. RE:
The inherent Direct Current resistance of a speaker's voice coil.
Submitted on Thursday, November 05, 2009 5:55:25 PM

13. 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.
Submitted on Tuesday, June 29, 2010 5:55:25 PM

14. Receiver-An audio component that combines a pre-amplifier, amplifier(s) and tuner in one chassis. A Dolby Prologic Receiver also contains a Dolby Prologic decoder for surround sound.
Submitted on Thursday, October 16, 2008 5:55:25 PM

15. Relay:-An electromechanical device that permits a small amount of current to control a much larger amount of current. A 12-volt automotive relay typically draws less than 100 mA but can switch 30 amps or more. (e.g., In order to get our power doors locks to work automatically with our new alarm, you will have to purchase two 12 volt relays for each door.)
Submitted on Tuesday, July 01, 2008 5:55:25 PM

16. Relay:
An electromechanical device that permits a small amount of current to control a much larger amount of current. A 12-volt automotive relay typically draws less than 100 mA but can switch 30 amps or more. (e.g., In order to get our power doors locks to work automatically with our new alarm, you will have to purchase two 12 volt relays for each door.)
Submitted on Saturday, August 09, 2008 5:55:25 PM

17. Rem or 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.
Submitted on Friday, May 22, 2009 5:55:25 PM

18. Remote Control
Definition: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.
Submitted on Wednesday, July 23, 2008 5:55:25 PM

19. Removable Face-The type of dash installed deck that permits the controls and display to be easily removed for security. (e.g., We bought a removable face deck because we didn't want to carry around the entire player.)
Submitted on Wednesday, February 18, 2009 5:55:25 PM

20. Removable Face
The type of dash installed deck that permits the controls and display to be easily removed for security. (e.g., We bought a removable face deck because we didn't want to carry around the entire player.)
Submitted on Monday, May 18, 2009 5:55:25 PM

21. Resistance-Most all conductors of electrons exhibit a property called resistance. Resistance impedes the flow of current. It is measured in units called Ohms. With a water hose, resistance could be regarded as friction between the water and the hose. A larger hose would create less friction and have a lower resistance than a smaller hose. In electrical circuits, small round cylinders with wires on either end are called resistors. These typically reduce the flow of electrons to serve the specific requirements of the circuit elements, such as amplification or switching functions.
Submitted on Tuesday, January 06, 2009 5:55:25 PM

22. Resistance (Re):
In electrical or electronic circuits, a characteristic of a material that opposes the flow of electrons. Speakers have resistance that opposes current.
Submitted on Monday, April 28, 2008 5:55:25 PM

23. Resonance
Definition:The tendency for a mechanical or electrical systems to vibrate or resonate sympathetically at a certain frequency when stimulated by external energy. Every element and material has a particular natural resonance point. The job of the speaker designer is to minimize these output peaks whenever they appear so that a smooth response is created.
Submitted on Wednesday, January 14, 2009 5:55:25 PM

24. Resonant frequency
Any system has a resonance at some particular frequency. At that frequency, even a slight amount of energy can cause the system to vibrate. A stretched piano string, when plucked, will vibrate for a while at a certain fundamental frequency. Plucked again, it will again vibrate at that same frequency. This is its natural or resonant frequency. While this is the basis of musical instruments, it is undesirable in music-reproducing instruments like audio equipment.
Submitted on Wednesday, February 24, 2010 5:55:25 PM

25. Resonant Frequency
The frequency at which a speaker cone vibrates with the least inertia. The point on the spectrum at which it has the greatest amplitude relative to all other applied frequencies.
Submitted on Saturday, August 28, 2010 5:55:25 PM

26. Reverb-Abbreviation for reverberation, a complex blend of multiple interacting reflections within an enclosed space which combines with the direct sound from a source and defines the character of the sound in a room or hall. It is also used for a signal processor which can generate an approximation of natural reverb. (Caution
Submitted on Sunday, October 31, 2010 5:55:25 PM

27. Reverberant Field-The sound field that exists when the reflected sound at a listening position predominates over the direct sound from the source. This contrasts with near field effects. Layout, reflectivity and spatial parameters will strongly influence the creation of this situation.
Submitted on Wednesday, September 02, 2009 5:55:25 PM

28. RF Modulator:
A device that converts a signal (typically audio and/or video) into a radio frequency. This can be received by a tuner and converted to perceptible information
Submitted on Friday, November 28, 2008 5:55:25 PM

29. Ribbon Driver:The ribbon tweeter driver is a very thin corrugated aluminum "voice coil" hanging freely like a streamer in a side-by-side magnetic field. A ribbon is actually a type of dynamic driver, in which the voice coil is in the form of a flat, ribbon-shaped conductor which, positioned between opposite magnetic fields, actually becomes the diaphragm itself. The ribbon is free of the stretched film resonance's and obstructing magnets of the planar-magnetic, so it offers outstanding pulse response, uniform drive, and a good approximation of a line source, but the efficiency and impedance are both phenomenally low and the base technology is not usable as a woofer due to the small area. Most practical ribbons either use a step-down transformer or ask the amplifier to drive a ½ ohm load (not a practical solution for most).The ribbon cannot be used to produce low frequencies. To create a moving element large enough to generate frequencies lower than a few hundred Hertz would mean moving opposing magnetic poles so far apart that they no longer exert a sufficient magnetic field over the entire area of the ribbon. But, a ribbon offers very precise treble around, superior to dynamics or electrostatics. In many ways, a ribbon driver can be an excellent performer
Submitted on Tuesday, July 21, 2009 5:55:25 PM

30. Ribbon Speaker
A type of speaker that uses a pleated conductor suspended between magnets. Most true ribbons are tweeters only. Sometimes confused with magnetic-planar speakers.
Submitted on Friday, August 06, 2010 5:55:25 PM

31. Ringing:-The tendency for any vibrating surface to continue to produce the same frequency. This is limited by the decay time over which the inertia of other forces act to repress the motion. In acoustics, this tendency is known as reverberance. In human physiology, a condition called tinitus causes the sensation of ringing, which is actually a nerve disorder rather than a problem with the ear's mechanism.
Submitted on Wednesday, April 21, 2010 5:55:25 PM

32. Ripple (Amplifier):
A train of pulses that occurs when AC is changed to DC via a rectifier. These pulses are left on the DC if not filtered and regulated properly, or if toomuch current is being drawn.
Submitted on Sunday, September 06, 2009 5:55:25 PM

33. Ripple (Speaker):The maximum deviation from flat response, measured in decibels-it indicates the port's effect on woofer output.
Submitted on Saturday, June 14, 2008 5:55:25 PM

34. RMS
Definition:Root Mean Square is a formula that provides a reasonably accurate means of measuring and comparing continuous AC power. The use of this measure is preferred when matching system components, like amplifiers and recievers. (see Power Handling)
Submitted on Thursday, May 13, 2010 5:55:25 PM

35. 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.
Submitted on Thursday, March 18, 2010 5:55:25 PM

36. Roll Off:-A graduated reduction in the strength of audio output above and below certain specified frequencies. (See Crossover)
Submitted on Tuesday, June 10, 2008 5:55:25 PM

37. Roll-off (cut-off)
The attenuation that occurs at the lower or upper frequency range of a driver, network, or system. The roll-off frequency is usually defined as the frequency where response is reduced by -3 dB.
Submitted on Wednesday, February 03, 2010 5:55:25 PM

38. Roof-Mount Antenna:
A permanently-installed antenna located in the center of a vehicle's roof.
Submitted on Tuesday, February 16, 2010 5:55:25 PM

39. 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.
Submitted on Thursday, November 04, 2010 5:55:25 PM

40. 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.
Submitted on Friday, January 16, 2009 5:55:25 PM

41. RTA (Real Time Analyzer):A real time analyzer is used to measure the amplitude of several frequencies throughout the audio bandwidth of 20 Hz up to 20, 000 Hz. (e.g., We used an RTA to adjust my equalizer.)
Submitted on Sunday, July 19, 2009 5:55:25 PM

42. RTA (Real Time Analyzer)-A real time analyzer is used to measure the amplitude of several frequencies throughout the audio bandwidth of 20 Hz up to 20, 000 Hz. (e.g., We used an RTA to adjust my equalizer.)
Submitted on Monday, September 21, 2009 5:55:25 PM

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