A Compact Disc player is used to play CDs. The machine consists of a very sensitive reading mechanism that reads digital information from a CD. The CD player also contains digital-to-analog conversion circuits. These digitalto-analog conversion circuits convert the digital data stored on the CD into an analog audio signal that can be fed into a mixer or amplified for a loudspeaker.
For many community radio stations, CDs are the main source of audio other than the microphone. As a result, there is an enormous demand on the broadcast CD player. These machines are often in continuous use for up to 18 hours a day, and are opened and closed thousands of times each month.
A radio station environment demands ruggedness, reliability, and instant cueing from audio source equipment. This is why studio CD players are built differently, and have controls and other features that are different to those found on a domestic CD player. However, if you are familiar with domestic CD players, then a few minutes with the manual of a broadcast CD player will teach you all of the extra features.
Panasonic DMP-BD65 Blu-Ray Disc Player (Black)
Playing CDs in a player
The basic operation of a CD player is straightforward. It involves putting a CD in the machine, choosing the track you want to play, and then pressing the play button to start playback. The CD is usually placed in a tray that slides out of the body of the player. In some players there may be a slot for the CD instead of a tray. Consult the user manual for your particular CD player for specific instructions on its features and operation.
An open/close button opens the CD player's disc tray. Press it to open the tray and insert the CD.
Always place the CD in the disc tray with the label facing upwards. CDs can only be played on one side, and putting a CD in the wrong way round will cause the CD player to "freeze up" as it tries to read the CD. It will eventually give up trying, and you will be able to open the tray and take out the CD, but this wastes precious time. When the CD is in the tray correctly, press the open/close button again to close the tray.
Many broadcast CD players disable the open/close button if a CD is playing in the machine. This stops presenters from accidentally ejecting the wrong CD.
| Do not EVER push the tray closed, as this will damage the motor that opens the tray. Damaging the motor may cause the player to refuse to open or close at all. Avoid using special shaped CDs (heart shaped CDs, octagonal CDs etc.). Trying to play them may damage your CD player. |
Choosing and playing tracks
Choosing tracks on the CD involves pressing the TRACK or SEARCH buttons. Some CD players use a jog wheel instead of a button to select tracks. A jog wheel is a control that is turned instead of pushed like a button. Turning it clockwise (to the right) will increase the track number. Turning it anticlockwise (to the left) will decrease the track number.
Once you've selected a track, press the PLAY button to play that track. One of the marks of a good quality broadcast CD player is that when you press play, the machine starts playback instantly. There is no delay. These CD players "cue" the track when it is selected. This means the tracking mechanism in the machine immediately reads the sub-code on the disc and positions the read laser at the start of the track that is to be played ready for playback. These players often have a CUE button instead of a pause button, or an AUTO CUE control. This control flashes for the short time it takes the player to find the track. It then stays lit once the track is cued.
Some CD players may take a few seconds to start playback and do not start instantly once you've pressed PLAY. This short amount of time is taken by the CD player to look for the track you've chosen. To minimise the "dead air" created while the player locates the track, you can cue the player as follows:
- Use the track controls to select the track you want, and then press PAUSE.
- Make sure the pause indicator is showing, or that the elapsed time is shown as zero.
- When you are ready, press PLAY - and the track will play instantly.
Controlling CD players from an on-air mixer
Broadcast CD Players often use fader start, allowing them to be controlled from the studio mixing desk. In this case, the start button or the on-off buttons on the mixing desk can be used to play and pause the CD player. The mixing desk and the CD player have to be capable of using this feature if you want to use fader start.
Elapsed time and remaining time
The term elapsed time means the amount of time that has passed since the beginning of the track that is playing. The term remaining time means the amount of time left before the track comes to an end. Normally, the CD player's display shows elapsed time. That is, it counts up the seconds and minutes that have passed from the time the track started playing. A CD player used in a broadcast studio should also be able to display the remaining time, or the time left before the end of the track. This is an essential feature as it allows presenters to see how much time is left on a track, so that they can prepare the next item. Presenters don't want to be surprised when the track comes to an end. They must be prepared for the end of the track so that there is no dead air time while they set up the next item. You can choose whether elapsed time or remaining time is shown on the CD player's display by pressing a button marked TIME or DISPLAY.
One track at a time
Another important feature of broadcast CD players is that they should be able to play tracks one at time. Domestic players play tracks continuously from the beginning of the CD to the end. It is very rare that a station will play an entire CD from beginning to end. Normally stations play only one track from a CD and then an item from a different source - another CD player, or the MD, or a microphone. It makes your job much easier if you don't have to worry about stopping the CD player while starting the next item. This is why it is important that the CD player is capable of playing one track and then pausing itself. A button labelled SINGLE/CONT, or the AUTO CUE control, normally controls this. Pressing this button will put the player in single play mode - that is, it will play one track and then pause. Pressing the same button again make the machine continue with the next track. The play mode will be shown on the display.
Other functions
A LOOP function allows a part of a track to be looped - that is to be played over and over. The REPEAT function allows a track, or the whole CD, to be played repeatedly. A PROGRAMME PLAY function allows the running order of tracks on a CD to be programmed.
After the mixer and the microphones, the CD player is possibly the most important item in a community radio studio. So it is important to choose the right CD players for your station.
As we've said, your CD players need to be rugged and reliable. They must be chosen for their ability to play even dirty or scratched CDs. There are dramatic differences between CD players. There are many factors that are not easy to judge without experience. The experience of fellow broadcasters is valuable here. Ask around before buying CD players and see what other stations have to say.
Cleaning and maintaining CD players
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Connectors and connections for the player Typically, broadcast CD players have two stereo outputs, one balanced and one unbalanced. These usually use male XLR connectors for the balanced output, and RCA connectors for the unbalanced output. (Note that consumer grade CD players are often used in CR stations, and tend to have only the RCA outputs.) For RCA connectors, the left and right channels are usually colour coded, with red indicating right and white indicating left.
Most professional CD players also have digital outputs. These may be marked OPTICAL or S/PDIF (Sony-Philips Digital Interconnect Format). Using these outputs, the CD player feeds the digital information from the CD directly to a digital mixer or the digital input of a digital recording device, such as a computer, minidisc or DAT recorder. This avoids any loss of quality that may result from D/A conversion. Optical ouputs need a special optical cable.
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