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| FORMAT: CED | ||||||
DATE: 1983 PRICE: £300 [2005: £680] 42x42x11cm 6kg | |||||||
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| European CED players were made by Hitachi and GEC McMichael, and curiously are nothing like the equivalent american SelectaVision machines - even though the format is the same (apart from PAL / NTSC differences). | |
| CED uses 12-inch vinyl discs, like audio LP's, which are read using a sapphire stylus. The disc is lubricated, and to protect the sticky surface from dust and damage, they are stored in protective sleeves or caddies. The whole thing is inserted into the machine, and then the caddy withdrawn leaving the disc behind ready to play. To remove it, the caddy is re-inserted, and when pulled out has the disc back inside it. So the user never sees the actual disc - and perhaps the phrase "video slab" would have been a better description! a CED disk half out of its caddy. |  |
 | The grooves on the disc are some 38 times finer than those on a normal LP record. They can be packed so tightly because they are only needed to guide the stylus, unlike a record where the audio signal is stored as wiggles in the groove itself. The signal is stored as variations in electrical capacitance. The disc and the stylus form part of an electricalcircuit, and a coating on the disc generates a capacitance. Stamped variations in this coating cause this capacitance to vary, and this affects the frequency of a resonant circuit. This frequency is turned back into the video signal. |
| Using the machine is simple, but perhaps not entirely intuitive. There is no power switch - it turns itself on when a disc is inserted, and automatically begins to play when the caddy is withdrawn. To stop playing, the Reset button is pressed to return the stylus to its "home" position; the caddy cannot be inserted until the machine has completed this process. Annoyingly, the machine turns itself off immediately a disc is withdrawn, which is irritating when you are simply turning a disc over since the TV screen reverts to hissing snow. As well as normal play, the VIP201P provides three different fast play speeds in both directions; the faster modes skip tracks, giving a jumping effect, while the x4 speed plays smoothly. There is no freeze-frame - the pause control simply gives a black screen, since the stylus is lifted from the groove - but there is a 4-frame repeat mode which gives a sort of picture pause, which you can step forward or backwards (if your fingers are dexterous enough!) Four frames is enough to give quite a flicker on moving sequences, of course, so it's not really a still picture. In fact a true still would be impossible for CED (at least without a frame buffer), since more than one frame is stored per revolution of the disc. | |
| A close-up of the CED disc surface, showing the boundary between two frames. |  |
| The fast play modes are the only way to move through the disc; there is no chapter- or time-search. So, one of the key advantages of disc over tape - instant access to any part of the recording - is not actually available on CED. Lights on the front tell you which side is playing, where in the disc you are (a light moving along a scale marked in minutes) and whether the disc is stereo/bilingual or mono. Bilingual discs provide two independent soundtracks: two different languages, or perhaps commentary and music, with a button allowing you to switch between them. | |
| CED discs play for up to 75 minutes a side (60 for NTSC); they can of course play for less than an hour, and the machine will reset itself automatically at the end of the recording. The picture quality is very good, somewhat crisper than standard VHS and with very pure blacks. The discs themselves are large and heavy, the caddy measuring about 32x35cm, and are much thicker than an LP or LaserDisc. Prototype and production CED discs |  |
| Since the stylus is in physical contact with the disc, playback - and particularly searching, which forces the needle to jump from one groove to another - will always cause a certain amount of wear and tear. Worn or scratched discs can jump, like records, but curiously the jumps caused by all but the most severe wear are not that obtrusive. | |
 | Internally, the machine is satisfyingly simple; it is effectively just an automatic record player. The disc is lowered onto a turntable (automatically on this model, though earlier versions used a manual raise/lower lever), and a motorised stylus unit (visible at the top of the picture) moves across and engages with the groove. The disc is played from outside toward the centre -- like a normal record, but unlike LaserDisc -- at 500 rpm, or 3 frames per rotation. |
| The stylus carriage doesn't move smoothly, as you'd expect; instead the stylus is pulled to the side by the groove, and when this displacement gets too large the carriage moves over by a small step, "unbending" the stylus and repeating the cycle. The needle itself is raised and lowered by a solenoid, and a felt pad at the "parked" position cleans it. Unlike TED there's no "resharpening" mechanism, and the stylus will eventually wear out. A worn stylus tends to jump, rather than give a poor picture. | |
 | The stylus unit can be removed for cleaning or replacement, via a cover on the left. The fact that this is easy to open, and not hidden away from the casual user, suggests that such actions were needed relatively frequently... The stylus compartment opened, with the stylus itself laying on top of the machine. Drop it in, close the lid, and you're ready to go again. |
| Like records, the discs are not always pressed perfectly centrally, in which case the stylus can be seen to wobble from side to side as it plays, and can be warped so the stylus moves up and down as the disc spins. None of this seems to affect either the picture or the sound, so the machine must compensate in some way - even minor variations in the timing of the video signal could cause the picture to judder, roll or even break up completely. |
| There was also a budget version, the VIP101P, which was as minimal as you could get -- no remote control, no AV outputs, and a single speed, forward-only fast search. Mono sound meant no dual-language playback, of course, and even the case was cheaper - a simple black plastic, not the elegant metallic silver of the 201. |  |
 The minimalist control panel of the "cheap as chips" 101 model. | |
