1 inch C.

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Recording device

1 inch C (also 1 "C ) was a video tape format developed by Ampex and Sony in 1976 and introduced in 1978.

It used a 1 inch wide magnetic tape and replaced the then established quadruplex format in the professional video and TV industry (colloquially mostly called “2 inch quad”, in literature “2 inch quadruplex”) because it is not only smaller and was lighter, but also had slightly better video quality and required less maintenance, energy and space. Experience from other tape formats such as the 1-inch A and 1-inch B systems, as well as the relatively young U-matic, were no doubt included.

1-inch C machines have not been built since the early 1990s.

The record

A composite signal is recorded, which is recorded using the “Direct FM” method. Four channels of longitudinal audio can be recorded, but the machine typically only allows three tracks to be recorded since the fourth track is used as the sync track. The third track can be used to record the longitudinal time code (LTC) according to EBU / SMPTE . The Vertical Interval TimeCode (VITC) can also be recorded in the image track .

Mobile devices

For the first time, portable recorders in suitcase format were available for electronic reporting . The reels, the size of a plate, were arranged axially one behind the other and the tape was wound diagonally around the head drum - here arranged axially parallel.

Technical specifications

The video bandwidth (more precisely: resolution) ranges from 25 Hz to 5.5 MHz, a specification that was only achieved again in 1986 by the BetacamSP system. The speed of the belt was just under 24 cm / s, which corresponds to a relative speed of 21.4 m / s. There were two reel sizes: 20 minutes the small reel, 60 or later 90 minutes the big one.

These machines, the BVH series from Sony, can only be found in console cabinets, because a Time Base Corrector is absolutely necessary even to display the image on a monitor , as the drive results in a lot of inaccuracies in the pure signal. In addition to the MAZ, a waveformer, a vectorscope (both can be seen in the picture above right next to the monitor), a monitor and the TBC and usually a listening speaker are installed in such a console.

The TBC is built into the console under the machine. The visible gauges show the audio level (the three left) and the video level (right).

The tape is looped around the head drum in the form of an omega , the position of this in the machine results in the corresponding symbol of the format (see also the picture below).

Special cases

  • In one variant (in the last generation of devices in the BVH-3000 series) the tape was threaded in using compressed air to prevent damage to the tape and the heads.
  • Supermotion was developed for sports broadcasts - a way of recording 525 lines / 29.97 fields in the NTSC area, now with 180 fields with the same number of lines.
  • "Delta t" recording was one way of making recordings that deviated from normal tape speed . It was possible to record single images, step-by-step recording of single images in a fixed grid as well as "slow motion record", this was effected by a special type of so-called DT heads (dynamic tracking, in German: tracking).

  • SONY portable 1-inch C machine

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  • Jürgen Burghardt: Manual of the professional video recorder . edition filmwerkstatt, Essen 1994, pp. 447–455