(BETA FOUR) SPEED?|
The answer lies within the realm of physical, mechanical and technical limitations. While slowing down the tape travel speed could certainly be accomplished the outcome would have been undesirable. This reduction in tape speed had already been done twice to both formats (Beta and VHS) just to gain more recording time but the picture and sound suffered each time. At the slowest speed Betas picture becomes grainy and unpredictable and with VHS it become almost unwatchable. This happens because the tape is traveling so slow. The recording surface is smaller, strength is reduced and the scans are almost on top of each other. Azimuth recording helps reduce crosstalk but the machine has to be running in top shape to show a good picture. Heat build up and head wear also becomes a problem. New head compositions helped offset these issues slightly but where slower speed really becomes a nuisance is in the audio. Compare frequency responses for the three speeds. The original
 speed comes in at a respectable 50—12,000 Hz, Sony only claimed 10,000 in there brochure. 50—10,000 Hz for  and for  it is a dismal 50—7,000 Hz. VHS faired much worse at their slowest speed. We're talking Edision phonograph here folks. Wax cylinder audio. Also distortion like Wow and flutter* at slow speeds begins to make the audio very unpleasant to listen to. Running a capstan at the slower speeds requires a very well behaved control system indeed to keep this problem a bay. and near perfect tape travel. Producing a slower running speed to accommodate a speed (or maybe it would be  ) would have certainly required a new approach to recording the audio. Betahi-fi† (which was to come after the recording time battle was over) would have made better audio possible because it uses the rotating video heads, not the stationary magnetic head, for stereo sound recording, No, the slow speed would not have been practical for other reasons. Slowing everything way down causes picture stability issues, in any VCR. Wow and flutter* which makes audio unpleasant to listen to also makes the video more difficult to remain uniform and steady. Even the slightest imperfection in the tape travel has a remarkably bad affect on the picture. suffers some from this very problem. VHS is even worse. To get good steady normal audio (monaural) and picture from this slowest speed requires a machine that operates at its best. And as these VCRs get older and their parts start to age and wear, wow and flutter correction becomes a factor to be reckoned with. †Betahi-fi is the revolutionary recording system that Sony developed to deliver superior stereo sound quality to video recording. To find out about it click here. (A new window replaces this one.) *Wow and flutter. In sound reproduction wow is a waver in a reproduced tone or group of tones that is caused by irregularities in turntable or tape drive (speed) during recording, duplication, or reproduction. Think of an LP record with the hole off center. Low-frequency irregularities cause flutter and are recognized aurally as fluctuations in pitch. Irregularities that occur at higher frequencies are called flutter and cause a roughening of the tone: a piano sounds like a harp, and voices waver with small, rapid variations above and below proper pitch. Included among the causes of wow and flutter in disks are high spots in drive rollers and an off-centre hole in the disk. In tape and film reproducers, characteristic causes include nonuniform tension in take-up and playoff reels and mechanical distortion of the tape. Low-frequency background noise, either recorded on disk or tape from the recording mechanism or added to the reproduced tone from the reproducing mechanism, is known as rumble and is usually the result of vibration of the drive mechanism. (source: Encyclopedia Britannica also see Dolby® and dbx® sound processing by clicking here.) To go back to the Beta speeds page click here. |