This page features digital VTRs built by Ampex. This is the last generation of machines built by Ampex, and one of these is (March 2001) still in production. From here on, VTRs will probably cease to be VTRs per se, but instead will become rotary head digital data recorders. The current hot product of Ampex is such a machine, the Ampex DST fromat. Even though it is not a VTR, it is listed here, as it's heritage lies in video, and it's most common use is in video file servers.
The ACR-225 has an interesting history. It was concieved as a product to bring the advantages of digital technology to the average TV station. In 1986, digital was still very new, with D-1 just barely in production by Sony. While D-1 is (And still is) a great format, it was a componenet video format. This was a major problem for most TV stations of the time, as they were wired primarily for composite video. D-1 was also a conservative format, which used a low coercivity tape. Starting with the D-1 cassette shell, Ampex designed a composite digital spot player, which came to be called the ACR-225. This format was the first digital format to take advantage of the performance of the new metal particle tapes. Although this format was originally to be a closed format (Native to the ACR-225 only), Sony convinced Ampex that there was a potential to use this as a production format. So, out of the ACR-225 came the D-2 format. By the time the ACR-225 was into production, D-2 was a recognized format, although no machines had been built yet.
Unfortunately, the ACR-225 had a troubled history, and most of the machines underwent a stem-to-stern rebuild in 1991-1992. The resulting machine was much more relaible, but it was too late. The rise of digital compression, the emergence of video file servers, and the sheer cost of the machine ($300,000+) gave the ACR-225 a short market lifetime. Not many were made, and very few are still in service.
The D-2 format was considerably more sucessful than the ACR-225, and was poised to become a major standard. However, digital compression technology quickly ended D-2's quick rise to widespread acceptance. Still, a lot of D-2 machines were sold, and many are still in use.
You can learn more about the ACR-225 on the page devoted to the ACR-225 on this site. Quadruplex Park has an ACR-225.
The VPR-300 is the D-2 production recorder that arose out of the development of the ACR-225. It shares the tape transport, and much of the electronics with the ACR-225. Although Sony came out with a D-2 machine before Ampex, the VPR-300 was considerably more advanced. In the tradition of the AVR-1 and VPR-3, the transport employed air lubricated guides and a pinch rollerless (Not vaccuum) capstan. The threading mechanism is the most advanced ever developed, and is designed to thread a tape in under 3 seconds, in two stages. The tension arms are driven by motors rather than being pushed around by the threading ring. In all there are 10 motors in the tape transport! There are no limit sensors on any of the moving parts. Instead, the machine learns where the mechanical components are by measuring motor currents. This makes for a low maintenance tape transport. Tape handling is so smooth, you can hardly tell tape is moving when it is blazing through the transport at 300 ips in shuttle!
Due to it's late appearence, it's larger size and the sudden demise of D-2, the VPR-300 was not as popular as it could have been. Lathough these machines are not rare, they are not common, either.
The VPR-200 was a simplified version of the VPR-300. It was designed more for everyday tape room operations than for production. As such, it did not have the extensive editing capability of the VPR-300. Although the VPR-200 uses exactly the same transport as the VPR-300, it has been said that the transports were constructed with parts that were slightly 'looser' in mechanical and electrical tolerances than the parts that went into the VPR-300's. (Most of the electronics are interchangeable, however.) The softare has built-in limits not found in the VPR-300, such as only 60 X search speed. The control panel also had a lot more 'hard' controls and meters, and relied less on the display. Last, but not least, there are built in monitor speakers in the VPR-200 thant are not present in the VPR-300.
Sorry, there is no picture of a VPR-250.
The VPR-250 was a VPR-200 that could accept only the two smallest sizs of D-2 cassettes.
This machine is an important VTR in VTR history, as it is the first VTR to use lossy compression to reduce data rate. This was Ampex's answer to the growing move towards component videotape formats. The compression employed is a (oddly enough!) DCT-based 2:1 compression that is for all intents and purposes transparent. The tape and transport is the same as for the ACR-225 and the VPR-XXX production machines. Although this machine has never sold in large numbers (It is still in production as of March, 2001), a number of major facilities have adopted DCT as their component format. This machine will probably be the last VTR marketed as a VTR by Ampex. From here, we move into the realm of rotary head digital data recorders.
Sorry, there is no picture of a DST machine.
DST is Ampex's current high-end data recorder. This format is based on the previous Ampex digital VTR designs. Briefly called Datastore, this series of machines uses the same tape transport as all the other Ampex digital machines. As a result, it can do things no other digital tape drive can do-- transfer data at a whopping 20 MB/sec continuously, and access files on the tape in a random manner like a disk drive. The data error rate is the lowest of any tape system on the market, at 1 in 10e17 bits read!. The format is supported by many software platforms, most notably those used for large-scale digital video archives. The standalone DST 312 drive can store up to 660 GB on a single large DD-2 cassette. The smaller two sizes of tape can hold 100 and 300 GB, respectively. (These are uncompressed capacities!) The top-of-the-line DST 812 automated tape library can hold 25.6 TB(!) in 256 small cassettes. This machine is essentially a repackaged ACR-225. The DST 712 can be ganged to other DST 712's to build even larger libraries. For instance, four of these machines ganged will give a storage capacity of 46.4 TB! (That's 2148 hours of digital video at 48 mbps!) Look for this format to go places in large scale facilities.