Posts Tagged ‘Ampex’

1″ type A Video Tape – The Old Grey Whistle Test

Thursday, March 5th, 2015

Sometimes genuine rarities turn up at the Great Bear studio. Our recent acquisition of four reels of ‘missing, believed wiped’ test recordings of cult BBC TV show The Old Grey Whistle Test is one such example.Old Grey Whistle Test Ampex reel

It is not only the content of these recordings that are interesting, but their form too, because they were made on 1” type A videotape.

The Ampex Corporation introduced 1” Society of Motion Picture and Television Engineers (SMPTE) type A videotape in 1965.

The 1″ type A was ‘one of the first standardized reel-to-reel magnetic tape formats in the 1 inch (25 mm) width.’ In the US it had greatest success as an institutional and industrial format. It was not widely adopted in the broadcast world because it did not meet Federal Communications Commission (FCC) specifications for broadcast videotape formats—it was capable of 350 lines, while the NTSC standard was 525, PAL and SECAM were 625 (for more information on television standards visit this page, also note the upcoming conference ‘Standards, Disruptions and Values in Digital Culture and Communication‘ taking place November 2015).

According the VT Old Boys website, created by ex-BBC engineers in order to document the history of videotape used at the organisation, 2″ Quadruplex tape remained very much the norm for production until the end of the 1970s.

Yet the very existence of the Old Grey Whistle Test tapes suggests type A videotape was being used in some capacity in the broadcast world. Perhaps ADAPT, a project researching British television production technology from 1960-present, could help us solve this mystery?

Old Grey Whistle Test ReelFrom type A, to type B….

As these things go, type A was followed by type B, with this model developed by the German company Bosch. Introduced in 1976, type B was widely adopted in continental Europe, but not in UK and USA which gravitated toward the type C model, introduced by SONY/ Ampex, also in 1976. Type C then became the professional broadcast standard and was still being used well into the 1990s. It was able to record high quality composite video, and therefore had an advantage over component videos such as Betacam and MII that were ‘notoriously fussy and trouble-prone.‘ Type C also had fancy functions like still, shuttle, variable-speed playback and slow motion.

From a preservation assessment point of view, ‘one-inch open reel is especially susceptible to risks associated with age, hardware, and equipment obsolescence. It is also prone to risks common to other types of magnetic media, such as mould, binder deterioration, physical damage, and signal drop-outs.’

1" Type A Machine

The Preservation Self-Assessment Programme advise that ‘this format is especially vulnerable, and, based on content assessment, it should be a priority for reformatting.’

AMPEX made over 30 SMPTE type A models, the majority of which are listed here. Yet the number of working machines we have access to today is few and far between.

In years to come it will be common for people to say ‘it takes four 1” type A tape recorders to make a working one’, but remember where you heard the truism first.

Harvesting several of these hulking, table-top machines for spares and working parts is exactly how we are finding a way to transfer these rare tapes—further evidence that we need to take the threat of equipment obsolescence very seriously.

2″ Quad Video Tape Transfers – new service offered

Monday, March 3rd, 2014

We are pleased to announce that we are now able to support the transfer of 2″ Quadruplex Video Tape (PAL, SECAM & NTSC) to digital formats.

Quadruplex Scanning Diagram

2” Quad was a popular broadcast analogue video tape format whose halcyon period ran from the late 1950s to the 1970s. The first quad video tape recorder made by AMPEX in 1956 cost a modest $45,000 (that’s $386,993.38 in today’s money).

2” Quad revolutionized TV broadcasting which previously had been reliant on film-based formats, known in the industry as ‘kinescope‘ recordings. Kinescope film required significant amounts of skilled labour as well as time to develop, and within the USA, which has six different time zones, it was difficult to transport the film in a timely fashion to ensure broadcasts were aired on schedule.

To counter these problems, broadcasters sought to develop magnetic recording methods, that had proved so successful for audio, for use in the television industry.

The first experiments directly adapted the longitudinal recording method used to record analogue audio. This however was not successful because video recordings require more bandwidth than audio. Recording a video signal with stationary tape heads (as they are in the longitudinal method), meant that the tape had to be recorded at a very high speed in order accommodate sufficient bandwidth to reproduce a good quality video image. A lot of tape was used!

Ampex, who at the time owned the trademark marketing name for ‘videotape’, then developed a method where the tape heads moved quickly across the tape, rather than the other way round. On the 2” quad machine, four magnetic record/reproduce heads are mounted on a headwheel spinning transversely (width-wise) across the tape, striking the tape at a 90° angle. The recording method was not without problems because, the Toshiba Science Museum write, it ‘combined the signal segments from these four heads into a single video image’ which meant that ‘some colour distortion arose from the characteristics of the individual heads, and joints were visible between signal segments.’

Quad scanning

The limitations of Quadruplex recording influenced the development of the helical scan method, that was invented in Japan by Dr. Kenichi Sawazaki of the Mazda Research Laboratory, Toshiba, in 1954. Helical scanning records each segment of the signal as a diagonal stripe across the tape. ‘By forming a single diagonal, long track on two-inch-wide tape, it was possible to record a video signal on one tape using one head, with no joints’, resulting in a smoother signal. Helical scanning was later widely adopted as a recording method in broadcast and domestic markets due to its simplicity, flexibility, reliability and economical use of tape.

This brief history charting the development of 2″ Quad recording technologies reveals that efficiency and cost-effectiveness, alongside media quality, were key factors driving the innovation of video tape recording in the 1950s.

 

Digitising Ampex U-Matic KCS-20 Video Tapes

Wednesday, May 29th, 2013

We are currently digitising a collection of U-Matic Ampex KCS-20 video tapes for Keith Barnfather, the founder of Reeltime Pictures.

Reeltime Pictures are most well-known for their production of documentaries about the BBC series Doctor Who. They also made Doctor Who spin-off films, a kind of film equivalent of fan fiction, that revived old and often marginal characters from the popular TV series.

The tapes we were sent were Ampex’s U-Matic video tapes. For those of you out there that have recorded material on Ampex tape be it audio or video, we have bad news for you. While much magnetic tape is more robust than most people imagine, this is not true of tape made by Ampex in the 1970s and 1980s.

Nearly all Ampex tape degrades disgracefully with age. A common outcome is ‘sticky shed syndrome,‘ a condition created by the deterioration of the binders in a magnetic tape which hold the iron oxide magnetic coating to its plastic carrier. So common was this problem with Ampex tape that the company patented the process of baking the tape (to be done strictly at the temperature 54 Centrigade, for a period of 16 hours), that would enable the tape to be played back.

ampex-umatic-tapes-dehydrating

In order to migrate the Ampex video tapes to a digital format they have, therefore, to be dehydrated in our incubator. This is careful process where we remove the tape from its outer shell to minimise ‘outgassing‘. Outgassing refers to the release of a gas that has become dissolved, trapped, frozen or absorbed in material. This can have significant effects if the released gas collects in a closed environment where air is stagnant or recirculated. The smell of new cars is a good example of outgassing that most people are familiar with.

When baking a tape in an enclosed incubator, it can therefore be vulnerable to the potential release of gasses from the shell, as well as the tape and its constituent material parts. Removing the shell primarily minimises danger to the tape, as it is difficult to know in advance what chemicals will be released when baking occurs.

It is important to stress that tape dehydration needs to be done in a controlled manner within a specifically designed lab incubator. This enables the temperature to be carefully regulated to the degree. Such precision cannot of course be achieved with domestic ovens (which are designed to cook things!), nor even food dehydrators, because there is very little temperature control.

So if you do have Ampex tapes, whether audio or video, we recommend that you treat them with extreme care, and if what is recorded on them is important to you, migrate them to a digital format before they almost certainly deteriorate.


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