Last week in history

Videotape Beginnings:
Friday, was the start of Videotape’s use in broadcast television.

55 years ago last week, CBS made broadcast (and videotape) history when it replayed the Nov. 30, 1956 evening news broadcast with Douglas Edwards from an Ampex Quad VTR at CBS Television City in Hollywood.

After recording the live feed coming down the network line from New York at 4 p.m. Pacific time, the program was played back three hours later and fed to the dozen West Coast CBS affiliates.
CBS Engineer John Radis supervised the process on this VRX-1000.
Jim Morrison is on the phone to the right of VRX-1000 transport, one of only 16 hand-built machines Ampex rushed to produce after debuting the VTR eight months before.
The two racks of tube equipment to the left contain the electronics for the recorder.
CBS created a videotape room that was kept busy recording network feeds for time-zone delay and eventually, programs produced in the studios at Television City.

The picture show this early VTR which was black and white only. The two racks are all tubes used for the transport operation and signal system. Video was recorded using a video modulated FM signal to reduce video noise in playback. Mono audio was recorded on one edge of the 2 inch tape as a linear track the same as reel to reel recording. When I started in Chicago, we would turn our’s on during the winter to keep the tape room warm. Standing in front was like a trip to a sauna. Years later we discovered the building maintenance people had removed the fuses in the duct heater and had forgot to replace them.



That is just way too cool.

Al, you should do a workshop at Championship where all you do is talk about the cool things you have done in your life.

That could take five minutes or all weekend. Depends on how you look at it!

“Engineers are not boring people. We are just easily excited by boring things.” :smiley:

That is very, very cool. Amazing all of the technology we had before it was easy to stuff a few million tiny transistors in everything!

Well said. While we think it’s awesome that you helped with a revolution in technology, for a lot of people, it would not make a good story time story.

Also, LOL at the maintenance men who stole your fuses. You were almost at the forefront of the magic smoke revolution, too.

Thanks for the history reminder. Ampex taught me how to be a good engineer. I missed most of the founders, but they were always a hot bed of very brilliant people. I owned the drafting table that the Original VTR electronics were designed on ($25 surplus).

Ampex had an excellent internal museum that had many of the early machines, as well as the precursor German wire recorders and other related technology.

There is still a group in Mountain View that is keeping at least one of the Quad recorders working to transcribe and preserve historic recordings.

Learn from history then make your own


Al shut down Analog TV as well. I vote for a weekend session…

The VCR was a revolution based on a simple idea: Scan the tape faster, much faster, than ever before. A typical 1/4" reel-to-reel tape speed is 7.5 inches per second, giving a maximum frequency reproduction (limited by the tape) of about 16 kHz. Video has significant energy over 2 MHz, more than 100 times higher. Early experiments tried running tape at hundreds of inches per second, but as you can imagine it wasn’t very practical (or good).

Someone brilliant at Ampex wondered why they had to move the tape so fast - instead, they moved the tape head past the tape very fast, using a rotating drum to ‘stripe’ the tape at a diagonal*. It worked, and made Ampex THE tape company for quite a long time.

Look it up, the technology is fascinating.

*Helical, actually, but practically diagonal.

You can learn all about how video recorders work, including the helical concept Don referenced from Tim Hunkin and Rex Garrod on The Secret Life of Machines…

Part 1
Part 2
Part 3

I always wondered why the heads in a VCR were tilted, and why they spun. (The short answer is here.)

Have any of your students had a chance to see the museum? One of the design team on this VTR was Ray Dolby, yep same guy. When I started, we only used this machine when nothing else would do or we needed heat. Our other machines were 1200 and 2000 series machines. However, when we started producing Soundstage, we need to record in stereo. Ampex had no interest at the time so we developed two methods. One involved recording the second channel on the cue track. This required a 240 Hz notch filter to cut out the adjacent control track but the 960 Hz video track still got into the channel. We then modified a two track head and installed it in place of the mono head on a special audio block using Inovonics stereo record amps with Dolby B noise reduction. As you know Ampex eventually thought ours was a good idea and added it to the AVR 2 and subsequent production machines. We eventually added Dolby A when it became available to all of our machines and Dolby made a card for our C series decks that became standard options in the VPR2. The VPR 80 didn’t have enough room so the Dolby frames were external.

See here for the discussion of Quadraplex recording.