Multi-Disc Changers Glossary
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Anti-shock Memory Buffer
Some CD changers have a memory circuit which reads ahead on a disc and stores several seconds of musical data. When the changer is jolted and the laser mistracks, the unit plays from this reservoir of data so you don't hear the skip.
CD-R, CD-RW Compatibility
CD changers with this capability can play audio CD-Rs and/or CD-RWs as well as prerecorded CDs.
Some compact discs contain CD Text data that include artist name, disc name, and track name. CD Text-capable CD changers automatically read and store this information for display on the readout of compatible receivers.
Custom File is the name Sony gives to the special programming options available on many UniLink controllers and changers. With a Custom File-capable controller and changer, your system remembers and displays titles of up to 8 characters which you key in for as many as 110 of your discs. The changer also skips over specific tracks you've deleted from any of these 110 CDs, unless you tell it to do otherwise.
Custom File Plus
An enhancement to Sony's Custom File programming system. With a Custom File Plus capable changer and controller, you can use the List feature to scroll through the titles of CDs currently in the changer without interrupting playback. You also get Program Play, which allows you to create two separate playlists of up to 12 tracks each, which the changer then remembers and plays back on demand when the appropriate discs are in the changer.
Digital-to-Analog (D/A) converters
Changers and CD players use a D/A converter to convert digital 1s and 0s back into analog audio signals. Musical media like CDs and memory cards store audio data in binary, digital form. This digital data is an accurate, noise-free reproduction of recorded signals, but in digital form it doesn't sound like music to your ears. The D/A converter translates the digital info back into music — that's why it's so important to your changer/player's performance.
Digital Media Files
Music which has been subjected to data compression — allowing users to store many hours of music as computer files. Some CD changers can play discs that are loaded with MP3, WMA, AAC, and/or uncompressed WAV files.
This feature lets you assign a name to each disc in your changer — the name will appear on the in-dash display when that disc is loaded.
Some changer/controller combinations let you specify exactly which tracks will play on a CD. Frequently, these systems allow you to program the sequence of disc and track playback.
D.R.I.V.E. Distortion Reduction Circuitry
Kenwood's name for its circuit which uses several low-pass filters and extremely high-speed switching to eliminate distortion inherent in the digital-to-analog conversion process.
FM Add-on or FM Modulated Changers
An FM modulated changer may be added to any FM car radio, factory systems included. Add-on FM changer packages consist of a controller (a wired remote/display), an RF (radio frequency) interface, and usually a changer. By converting the CD audio signal into an FM radio signal, a "station" is simply tuned in on the existing FM radio. Disc and track changes can be made with the controls on the display unit or, when it is included in the package, the wireless remote control. Separate FM modulator adapters are also available to connect outboard audio sources to your car radio. For more information, visit our Changer Installation, and Frequently Asked Questions pages.
This feature lets you press a button to hear the first several seconds of each track on the currently selected disc, or the first several seconds of each disc in the magazine. Depending on its manufacturer, your changer will perform one or both of these tasks.
The single cable connection on JVC changers which carries signal, power, and ground.
MultiMediaCard (MMC) and Secure Digital (SD) card
A form of removable memory, MMMC and SD cards are available in a range of sizes, . They are small (about the size of a postage stamp), durable, and provide solid-state memory and fast read/write speeds. MMCs have mostly been replaced by SD cards, or Secure Digital, memory.
OEM Changer Adapters
These adapters allow you to connect an aftermarket changer to your changer-controlling factory radio. These adapters are not universal — each adapter works only in certain types of cars and with a specific brand of CD changer. Some manufacturers offer changer/adapter packages that will work with your factory radio.
This feature lets you play the currently selected disc track repeatedly or the currently selected disc repeatedly.
When a CD changer reads a disc, a group of servos control the laser's tracking, focus, and the way the disc is rotated. Playing a compact disc in a car puts any CD changer to the test — road vibration, high sound pressure levels, and dirty CDs can all conspire to cause skips.
Servo Control uses real time monitoring and adjustment of the laser's servos to insure stable, consistent playback. Hit a rough road, and the changer immediately handles the problem. Run into a bad part of the disc, and the changer "learns" the condition, adjusts itself, and plays right through most rough spots.
This feature lets you play the tracks on the currently selected disc in a random order or play each track on each disc in the changer in a random order.
UniLink is the name Sony gives to the technology currently used by controllers to "tell" a CD or MD changer what to do. The controller and changer are connected by a UniLink cable that handles the connections for power and control, conveniently eliminating the need to run separate power and ground connections, except in the case of FM modulated changers. The audio signal is carried by a separate pair of RCA cables.
Using optional adaptors, a UniLink system can control as many as ten changers. An optional adaptor is also available to connect an older 13-pin style Sony changer to a UniLink controller (available directly from Sony).
Some high-performance CD changers feature a circuit that detects a series of zeros in the digital bitstream (no music) and mutes the output signal so you'll hear dead silence between tracks on a CD.