Tape Recording Technology
The date: April 14, 1956
The place: Normandy Lounge, Chicago
The event: Annual CBS-TV affiliates meeting
As the impact of what was happening before
them sank in, the silence was broken by an equally sudden roar
of applause, cheers, whistles and stamping of feet. The curtain
behind the podium opened to reveal a large gray console that
looked like a gargantuan audio tape recorder, with overgrown
reels of tape on its horizontal top plate. Hovering over this
whirring magnetic monster, with looks of obvious relief, were
a few of the engineers responsible for developing it.
The race to develop television in the 1920s
and '30s by Baird, Zworykin, Farnsworth and many others, was re-enacted
in the 1950s by Bing Crosby Enterprises, Ampex, RCA and firms in
Germany, France and Japan. All were struggling to develop a means
of storing complex video signals on magnetic tape.
The concept of magnetic storage was developed
by Vladimir Poulsen (Denmark) in 1899. But the technology remained
a laboratory concept until the Germans developed their Magnetophone tape
recorder. Starting in 1931, AEG engineers in Berlin began working
on the Magnetrophone (a dc-bias machine) while BASF chemists produced
the first modern iron-oxide tape formula. The discovery of ac-bias
recording (in the U.S.) in 1939-40 led to regular on-air use of
the Magnetophone on German radio by 1941.
John T. (Jack) Mullin is credited for bringing
the Magnetophone to the United States after the war. Mullin served
in the U.S. Army Signal Corps and was assigned to the RAF as a
liaison officer concerned with the interchange of technical information.
After the invasion of France, Mullin and his group set up shop
in Paris with the objective to ferret out developments in which
the Germans may have been active during the war and at the time
of their retreat. (See also Jack Mullin.)
About 6 of the Magnetophone machines had been
captured and tested as the war drew to a close, but Mullin found
them to be quite poor in dynamic range. The background noise, in
fact, was not even as good as a 78 RPM shellac record. The distortion
was high as well. A British army officer, however, told Mullin
about a machine being used at the studios of Radio Frankfurt that
provided remarkable dynamic range and low distortion. Mullin, while
skeptical, ventured to the station. He later wrote the following
account of his visit:
"Radio Frankfurt had vacated the city during
heavy bombing raids and had relocated to a large house at a resort
spa north of the city in a small town called Bra Nauheim. The station
was being directed by the U.S. Armed Forces Radio Service, but
the German staff was still operating and maintaining the equipment.
I asked if I might hear one of the tape machines
they were using. An order was directed to one of the technicians
and I was taken into a room in which there was a large loudspeaker
and two of the Magnetophones. The mechanism appeared to be the
same as the ones we had in Paris, but there was an obvious difference
in the electronics.
The technician placed a roll of tape on one
of the machines and started it. Suddenly, out of complete silence,
an orchestra bloomed into being with fidelity such as I have never
heard in my life. From deep resonant bass to the shimmering of
the flute it was all there. It was clean! It was free from any
noticeable distortion. And if that were not enough, the dynamic
range was fantastic compared with anything I had ever experienced."
Mullin's assistant photographed all of the schematic
diagrams and instruction manuals (which were in German), and talked
the officer in charge of the Frankfurt station out of a few rolls
of tape. Mulling later brought two of the Magnetophones back with
him to the United States. After some modifications and tests, he
was ready to demonstrate the capabilities of the machines. Through
a stroke of good fortune, Mullin was asked to demonstrate the capabilities
of his Magnetophones to singer Bing Crosby. (See the related article, The
Magic of Magnetic Tape.)
The demonstration was a huge success, and led
to the development of the first audio recorder produced in the
United States, the Ampex model 200. The machine was first used
by ABC in 1948. The rugged design of the model 200, and the financial
and political support for Crosby, turned industry skepticism about
magnetic recording into widespread confidence -- almost overnight.
Crosby later founded Bing Crosby Enterprises to conduct a variety
of broadcast and recording research.
Although many in broadcasting take video recording
for granted, it was not always with us. The early days of television
were solidly intertwined with film and film processing, and live
programming. By the late 1940s, TV engineers had already developed
a whole new field within broadcasting and teleproduction: TV recording.
Today, there are thousands of video recording specialists in the
world, but back in the late '40s only a few could lay claim to
that remarkable title. To understand the impact -- the revolution
-- of the videotape recorder on the TV industry, we must look at
life before the VTR, the days when video recording meant kinescope.
The kinescope dominated TV recording for time
delay in the early 1950s. A kinescope recorder was basically a
special 16mm or 35mm film camera mounted in a large box aimed at
a high quality monochrome video monitor (a kinescope). All things
considered, the kinescope made respectable and reliable TV recordings.
Most engineers called the process "kine" (pronounced "kinney")
The kinescope was quite a clever device. Its
film camera ran at a speed of 24 frames per second. Because the
TV image repeated at 60 fields (or 30 frames) per second, the film
had to move intermittently between video frames, and then be rock-steady
during exposure. Theoretically, the pulldown period for the film
frame should be during the video vertical interval of less than
2ms, something no mechanical contraption could do.
Several kine makers, such as RCA, Acme, General
Precision, Eastman Kodak and Palmer Films found various ways around
the problem. They developed novel shutter mechanisms that used
the extra six frames of the 30 frame video signal to move the film.
This action integrated the video half-images into what seemed like
smooth 24-frame-per-second film pictures. Of course, the kines
were played back on the air using regular 24-frame-per-second film
chains, so the conversion to film was complete.
The toughest operational problem with kines
was the shutter bar. Although recording engineers tried
to get precise synchronization between the camera shutter and the
video image, problems often surfaced. The various sources of sync
were usually locked to their own primary power references, causing
a dark line or shutter bar to drift through the filmed image. One
solution involved driving the kine film camera from signals locked
to the sync that was coming in with the video source, and then
stripping the sync a moment later.
Another problem with kine quality was the gray
scale. It was difficult to match the non-linear gray scale characteristics
of the video system. Often when engineers were able to get a good
film look on a kine recording, the image just didn't reproduce
well on the Iconoscope cameras used in film chains. Engineers were
continually fighting problems with kinescope phosphors, blooming
on white-colored objects, gamma transfer characteristics, variable
film sensitivity and chemical processing.
The kine image and optical audio quality often
left something to be desired, but the broadcast industry had no
choice. All three networks were using kines for time delay to the
During the early- and mid-1950s, the late afternoon
hours at the recording departments of the three network West Coast
operations centers were a beehive of activity. The fun started
early, with shows that were scheduled to air in California at 7:30
p.m. coming down the microwave link from New York at 4:30 p.m.
PST, the same shows that affiliates in other time zones were broadcasting
live. The only way for the West Coast to accomplish the necessary
time delay was through the use of kinescopes.
Using CBS as the example, here's how kine transcription
worked: CBS engineers at Television City in Hollywood recorded
the show on their Acme 35mm kinescope recorders, with a 16mm Eastman
running as backup. As soon as the first 34-minute reel was empty
and the switch was make to the second kine, a courier grabbed the
first 35mm reel and rushed it over to the film processor on Santa
Monica Boulevard, about two miles away. Meanwhile, a second courier,
taking a different street route, transported the 16mm backup to
the same lab.
As the film emerged from the dryers, it was
spooled onto reels and stuffed into cans, which the waiting couriers
rushed back across town to the CBS projection room. At the same
time, the third and fourth couriers were taking the second reels
of 35mm and 16mm film from the studio to the processor. Engineers
of the day called these hot kines, because at air time,
they sometimes still seemed warm from the film dryer, and they
really were hot off the press.
Video historian and veteran video engineer Albert
Abramson remembers a night at CBS Television City when the second
35mm reel of a program had not yet returned from the processor
and it was almost air time. The breathless courier showed up with
only a minute to go. Abramson says he never saw anyone thread and
cue up a film chain so fast! To his knowledge, nobody at any of
the network operations in Hollywood ever lost a show because of
a kine processing foul-up, although they all certainly used the
16mm backup on occasion.
By 1954, the cost of kinescoping for time delay
had gone sky-high. American TV operations used more raw film for
kines than all of the Hollywood film studios combined. It was estimated
that NBC used more than one million feet of film a month in its
New York facility alone to time-shift programs. The networks would
have gladly paid a king's ransom for an alternative TV recording
method. Enter magnetic recording.
Video Magnetic Recording
The earliest known proposal for the use of magnetic
recording to store pictures dates back to the late 1920s and a
British patent office grant to Boris Ritcheouluff of London. Ritcheouluff
designed a picture recorder of considerable ingenuity based on
the Poulsen machine, developed in Denmark many years before.
A 1932 German technical publication described
a series of schemes for picture telegraphy proposed by Dr. Fritz
Schroeter, professor at the Berlin Technischen Hochschule and a
director of Telefunken. The illustrations in the book quite clearly
resemble present day transverse and helical scanning formats.
In 1938, an Italian inventor by the name of
Luigi Marzocci filed a patent application for a variety of rotary
head recorders that were clearly intended for sound recording,
and so labeled in the patent. Nevertheless, the drawings are amazingly
similar to the arcuate and transverse video recording concepts
that came later with the first Ampex VTR. In fact, the company
that held the rights to Marzocci's invention were prompted to consider
legal action against Ampex after they commercialized their VTR.
Even as the Ampex group was developing the transverse
recorder, German engineer Eduard Schueller, working in Hamburg
for Telefunken, filed for a patent covering a two head helical
recorder that is almost identical in concept to some of the machines
later produced in the U.S., Japan, and Germany.
The Race Begins
As early as 1950, Jack Mullin, then Bing Crosby's
recordist and chief engineer, began working at the newly established
electronics division of Crosby Enterprises to develop a magnetic
TV recorder. Jack and colleague Wayne Johnson developed some interesting
prototype recorders that used fixed heads and high tape speeds
to achieve the high head-to-tape velocities needed for TV recording.
The Mullin-Crosby machine started out with 12
tracks at 120-inches/second (ips) on 1-inch tape. Ten tracks carried
the monochrome video information, a clock track provided control
synchronization and an FM audio track completed the format. The
basic theory was to use frequency division multiplexing with the
10 channels covering the desired video range. A bandwidth of 17kHz
per channel produced a cumulative spectrum of 1.7MHz, adequate
for monochrome reproduction. Sync was recorded on a separate track
to avoid the distortion effects of the band separation filters.
By 1952 Crosby Enterprises was inviting broadcasters
in to look at credible results of off-air black and white recordings.
There were, however, some severe picture impairments that would
require much improvement before the recorder could be considered
acceptable to broadcasters.
Three years later Mullin had the machine recording
color video using only five tracks total: Three for recording RGB
information, one for vertical and horizontal sync, and one for
the FM audio track. The 1/2-inch wide tape ran at 240ips. People
who saw the Crosby video prototype say the picture quality was
pretty good, except for a fuzzy screen-door look over the image.
After transverse video recording was introduced,
the Crosby project was acquired by 3M Company as their Mincom Division,
and was put to other recording tasks in the instrumentation field.
Meanwhile, David Sarnoff, the head of RCA, expected
his engineers to come up with a magnetic TV recorder. Sarnoff reportedly
wanted the machine and a few other innovations from RCA as a present
for the upcoming anniversary of his 50th year in the radio business.
The development team was headed by Dr. Harold Olson. The effort
resulted in a longitudinal, high speed VTR that made monochrome
and color pictures.
The first laboratory prototype was shown publicly
in 1953. It used 1/2-inch wide tape and ran at 30-feet/second (ft/s).
There were five tracks on the tape. A 7,000 foot reel ran for just
4 minutes. Subsequently, the tape speed was lowered to 20ft/s and
the playing time was increased to 15 minutes.
RCA felt confident enough with this advanced
color machine to make some program demonstrations at NBC in late
1955. It was even used for about two minutes on the air. The RCA
system reduced the incoming color video signal into its R-G-B elements,
each of which went on a separate track, as did the synchronizing
information. The 5th track carried FM audio information. The stationary
magnetic heads of one micron gap width could handle frequencies
up to 1.5MHz.
The RCA machine introduced many innovations
that became fairly standard on subsequent VTRs. Tape tension servos,
eddy current brakes, luminance/chrominance separation and sync
reinsertion -- familiar techniques today -- were all part of those
The BBC also saw the potential advantages of
a vision magnetic recorder, and in 1952 assigned Dr. Peter Axon
to lead a long-term effort in that direction. The machine was called
VERA (Vision Electronic Recording Apparatus) and was quite different
from its contemporaries. Many of the developments achieved in this
recorder served as departure points for subsequent helical VTRs
that were developed later.
The 1/2-inch tape moved at 16ft/s; a 21-inch
diameter reel gave 15 minutes of playing time. VERA was capable
of 3MHz bandwidth, a significant achievement for its era in longitudinal
recording. The fundamental approach involved the separation of
the video signal into two bands: the first for low frequencies
up to 100kHz, and the second for frequencies from 100kHz to 3MHz.
Low frequencies were recorded using FM while the high frequencies
were applied to the tape using AM.
Upon playback, the two frequency bands were
recombined to produce an image good enough to be put on the air
in 1958. VERA had many unique features, among the most notable
being heads made of ferrite cores clad with permalloy with a gap
width of 0.5 micron, and a closed-loop tape drive system that held
tape speed to within 0.04% by locking to an external sync generator
and comparing the sync off-tape with the reference source.
The BBC terminated the project when it became
evident that the transverse approach, introduced by Ampex, would
become the standard of the industry. As a matter of fact, Dr. Axon
also recognized this potential and later became managing director
of the Ampex Reading (England) operation.
While little information was coming out of Japan
in those days, it later became evident that several Japanese organizations
were also experimenting with videotape recording. In 1953, Toshiba
was working on a crude helical scan system, which five years later
evolved into both single- and dual-head prototypes.
None of the early efforts by Crosby, RCA, the
BBC or Toshiba resulted in a product that was ready for the marketplace.
It wasn't until a group of young upstarts from Redwood City, CA,
perfected their concept of the VTR that the industry's desire for
a videotape recorder would be satisfied.
The Ampex Mark IV
In the early 1950s, Ampex Corporation engineers
began work that would eventually result in the first practical
broadcast quality videotape recorder. In less than a decade, recording
technology would advanced from a high frequency limit of 20kHz
to video magnetic frequencies ranging to 5MHz or higher.
The development of the videotape recorder was
the product of years of hard -- and at times inspired -- work by
a 6 man engineering team at Ampex. At times progress was slow,
and the project was put on the shelf more than once. The key members
of the engineering team that eventually made the electromechanical
monster work included:
- Charles Ginsburg, the team leader
- Charles Anderson, the "father of FM
- Ray Dolby, the ingenious engineering student
- Alex Maxey, the vacuum tension experimenter
- Fred Pfost, the master of tape head design
- Shelby Henderson, the model maker
In retrospect, all members of the small team
that developed the Ampex VTR credit one individual for its eventual
emergence. The accolade is not so much for his technical skills,
which were considerable, as for his tenacity and purposeful single-mindedness
in the face of every possible adversity that lack of time, money
and technical precedent can impose. That man was Charles Ginsburg,
a young obscure engineer who joined Ampex in late 1951 specifically
to make pictures on tape, and did so to the utter amazement of
his peers in the rest of the industry.
At the beginning of the effort in 1951, the
concept of the video recorder system involved the use of three
tape heads mounted on the surface of a drum, scanning in an arcuate
fashion the surface of a 2-inch-wide tape. The tape-to-head speed
was to be about 2,500ips (with the tape moving at 30ips). This
speed proved to be impractical, however, and eventually was set
at 1500ips. Designers hoped the system would give dependable recording
frequencies as high as 2.5MHz. Progress was slow in the early months
of the project, but in October 1952 engineers were able to demonstrate
an almost unrecognizable picture that still was promising enough
to maintain management's enthusiasm in the video recording project.
By March 1953, a second machine had been built
using four heads mounted on the plane face of the drum (instead
of three). An amplitude modulation system was used in the recorder
and a switching arrangement selected the proper heads during rotation
of the drum. The capstan motor was driven directly from the 60Hz
line frequency and the high speed drum motor was driven by a power
amplifier whose input was the fifth harmonic of that signal (300Hz).
A reference drum motor speed signal was recorded on the tape along
with the video information, and used during playback to provide
control for the drum motor power amplifier.
In September 1954, after several periods of
inactivity, the VTR project was recommenced in earnest, with several
significant technical changes. Instead of the arcuate sweep configuration,
engineers changed to a geometry that became standard in the late
1950s in which the tape wrapped transversely around the rotating
head drum. Consequently, the video information was written across
the moving tape in straight lines. An automatic gain control also
was developed to compensate for amplitude fluctuations of the rotating
head recording system.
Creating the head assembly was a monumental
task. Engineers had to develop a head unit that met stringent mechanical
and electrical specifications. Complicating the process were the
high centrifugal forces that the head assembly faced during operation.
In December 1954, the first picture was demonstrated
using the new geometry and modified electronics. In the words of
Charles Ginsburg, leader of the Ampex research team, "It took
a great deal of faith and understanding to be optimistic in the
face of some rather gross shortcomings in the reproduced picture." The
decision then was made to attack the video recording process from
a different perspective.
A recording system using vestigial sideband
frequency modulation was proposed to replace the amplitude modulation
technique. In January 1955, the first pictures were seen using
the FM video recording system. A few months later, the engineering
team gave a convincing demonstration to the Ampex board of directors.
Although the resolution was extremely low (the system bandwidth
was somewhat less than 1.5MHz) and the video monitor had to be
modified to compensate for horizontal instabilities generated by
the system, the images produced by the recorder were good enough
to persuade management that work should continue.
Development progressed with a number of changes
and improvements in the recording system. Vacuum-controlled tape
tension was introduced to the unit, and a radical redesign of the
tape heads (going to a sandwich-type of construction) was made.
The Final Push
In early February 1956, the engineering team
put on a demonstration for what was supposed to be a small Ampex
management group. About 30 company people showed up, however, for
the historic event. Ginsburg remembers the demonstration this way:
"For all of us on the engineering project,
this was the most dramatic demonstration we were to make. The guests
arrived, were seated, a few words were spoken to the effect that
we would show them what we had produced and the machine was put
in the playback mode to reproduce a program we had recorded an
"We then announced that we would record
a sequence and immediately play it back. We recorded for about
two minutes, rewound the tape and pushed the playback button. Completely
silent up to this point, the entire group rose to its feet and
shook the building with hand clapping and shouting."
A crash program followed the demonstration,
with introduction of the machine to the industry scheduled for
the National Association of Radio and Television Broadcasters (later
shortened to and hereafter referred to as NAB) Convention in Chicago,
just six weeks away. In the weeks that followed the demonstration
to Ampex management, a number of visitors were shown the video
recorder. Engineering executives from CBS, ABC, CBC and the BBC
were sworn to absolute secrecy and ushered in and out separately
so they would not see each other.
As the result of a visit by Bill Lodge of CBS,
arrangements were made to use a demonstration model, the Mark IV
machine, which had not yet been assembled, for a surprise showing
to the annual CBS affiliates meeting that was to occur the day
before the formal opening of the NAB.
With just six weeks to go before the show, working
hours were extended considerably to complete construction of the
Mark IV unit, and at the same time continue development work so
the picture to be demonstrated in Chicago would be as good as CBS
was expecting it to be. The activity became furious. The administrative
engineer for the now considerably enlarged group shed his business
suit in favor of work shirt and jeans. He spent most of his regular
time plus nights and weekends modifying mounting brackets for the
new Mark IV console, making cable assemblies and building re-designed
A three-year old idea of placing the switching
transients in the horizontal blanking interval was rushed into
hardware form as the blanking switcher and integrated into the
basic system as a toggle switch option. An automatic rotary head
deguassing system came into being to eliminate the necessity of
manually demagnetizing the video heads after a recording operation
and before playback.
Meanwhile, it has been decided that the Mark
III machine used for the Ampex management demonstration should
be used for a press demo on the same day that the NAB was to begin.
Therefore, while Mark III was being used for development work,
it also had to be prepared for the press appearance. The true orphan
of the project, the audio, which had been sadly neglected up to
this point, was made at least to approach professional standards.
Ampex management also gently suggested that
a piece of equipment that was to cost upwards of $50,000 should
look substantially more polished than the engineering models used
for demonstration purposes to date. The prototype machines were
housed in crude looking consoles and partially filled racks. A
more compact console and rack mounting system was developed to
accommodate the wishes of the Ampex brass and the expectations
of potential customers.
The long days and weeks paid off. The Mark IV
was complete and broken down into a number of pieces for shipment
to Chicago. Three days before the press demonstration, however,
the Redwood City machine was having severe mechanical trouble.
Some of the team left for Chicago and the rest stayed in Redwood
City to patch the Mark III back together.
The demonstrations were scheduled for Saturday.
By Thursday afternoon the Mark IV was assembled in Chicago and
was making the best pictures the team had yet seen on tape. A predictable
situation then occurred. The CBS engineering staff said the pictures
were not good enough. The signal-to-noise ratio was too low and
the noise banding was intolerable.
Between Thursday night and Friday night, the
team trimmed and adjusted the machine, aided by the last-minute
delivery of new tape samples that greatly exceeded the performance
of anything they had used before. The crew in Redwood City, meanwhile,
had solved their mechanical problems and was ready for the press
The Big Day
There was an air of normal conviviality among
the 200 or so station owners and managers attending the CBS television
affiliates meeting that preceded the opening of the 1956 NAB convention.
As the guests filed into the Normandy Lounge to listen to their
headquarters manager, William Lodge, deliver the annual report,
they had no inkling that this April 14, 1956 meeting would reveal
to the world a technical development that would change television
It was not out of the ordinary at such gatherings
to have a camera pointed at the podium and a few monitors set up
in the room so as to convey an aura of television. If any of those
in attendance noticed an unfamiliar high pitched whine, they probably
assumed that it was due to a faulty fluorescent lamp or some external
Lodge made his prepared presentation with what
seemed like a pregnant pause at the end. Suddenly, the monitors
in the room were showing what must have seemed to the audience
as an impossibility, for they were looking at an instant playback
of the Lodge speech, with an image clarity indistinguishable from
the original they had seen a few minutes earlier. There was a hushed
silence as those in the room tried to relate this assault on their
senses, with their prior knowledge that TV images could not be
immediately repeated by any known device. Cheers and applause then
There was no available monitor for the Ampex
team behind the curtain to check the playback before punching it
up on the TV screens in the other part of the room. As a result,
they had to operate on the blind faith that everything was working
well. That short silence at the beginning of the playback seemed
like an eternity to Ginsburg, Dolby, Anderson and Pfost.
The station executives crowded in around the
VTR, trapping the operating personnel against the machine, while
they pushed, elbowed and stood on chairs to get a glimpse of this
latest video marvel. The VTR crew, who just a few minutes earlier
were holding their breath in the fond hope that his hastily assembled
contraption would perform on cue, were now busily answering questions
from excited interrogators who were naturally curious about performance,
price and availability.
After news of the breakthrough spread throughout
the convention, pandemonium broke loose and Ampex was flooded with
orders. The era of videotape recording had arrived. Engineers who
witnessed the event still remark about its historical significance.
The demonstration machines were far from finished products, however.
The "Real Work" Begins
The next several months were just hard work
for the entire engineering team. Ampex had originally expected
to deliver 5 prototype machines beginning in late summer or early
fall to customers in government agencies for evaluation, along
with a gradual program leading to delivery of machines for TV use
starting in 1957. Now, however, the engineers were faced with the
pressure of producing 16 hand-built machines, most of them going
to broadcasters for immediate on-air use. At the same, they had
to gear up for full-scale production of VTRs for which the industry
Despite the subjectively good pictures demonstrated
in April 1956, much work remained to be accomplished. A review
of the tasks facing the team before releasing the first machine
for air use revealed how shaky the technical ground really was.
Some of the key tasks involved:
- Tape evaluation. Until then, neither the
personnel nor machine facilities nor technical advances were
sufficient to properly evaluate magnetic tape for video recording.
The tape program consumed many hundreds of man-hours and was
the cause of severe headaches to the tape manufacturer, Ampex
engineering staff and early network customers.
- Tape head life. The predicted head life for
the early machines was just 100 hours. Worse yet, the heads were
made in a tedious one-at-a-time fashion. The many parameters
in head construction, several of which had been varied madly
in cut-and-try fashion to squeeze out a few precious decibels
of signal-to-noise ratio for the April demonstrations, had to
be frozen to establish some standard before delivery of the first
machines to customers. At the same time, head construction had
to evolve into a semi-production process, rather than a one-at-a-time
- Processing hardware. A processing unit had
to be designed and built capable of providing blanking and sync
in the reproduced signal that was sufficiently free of noise
to allow the video to be handled without difficulty by conventional
stabilization amplifiers and clamps anywhere along the transmission
- Picture improvements. The picture reproduced
from tape had to be greatly improved over that shown in April
with respect to noise, resolution, overshoot and ringing, and
- Mechanical considerations. The entire machine
and all individual chassis had to be repackaged and tested. The
mechanical design details were endless. The top plate components
had to be not only reliable, but completely interchangeable.
On the Air!
The historic first broadcast via videotape was
the CBS airing of the Douglas Edward and the News program
on November 30, 1956, from New York. CBS Television City in Hollywood
replayed the broadcast three hours after it was received on the
West Coast. Confidence at CBS in the new machines was not all that
high, and for a month, the network ran a backup kinescope just
in case of a breakdown.
"Headhunting," as it was known at
the time, was a major problem in the early machines. Headhunting
caused picture jitter for home viewers with receivers that had
horizontal AFC circuits designed for fringe area reception. Viewer
complaints instigated a crash program to alleviate the defect before
CBS could make good on its threat to take the machines off the
air. Ampex engineers literally slept in the VTR room to have access
to the Mark IVs during non-broadcast hours, between 1:00 and 5:00
a.m. A lot of midnight oil was (literally) burned to solve the
In the following months, NBC and ABC followed
the CBS lead. Ampex built 16 Mark IV production prototypes in 1956-57
-- calling them the VRX-1000 -- before beginning production of
the VR-1000 in 1957.
RCA unveiled its version of the VTR, the TRT-1A,
in 1957. The machine used the same head and video systems as the
Ampex VR-1000. RCA began marketing the VTR process as quadruplex recording,
based on the fact that the machine had four video heads. The industry
soon adopted the shortened version of the name, terming it quad.
The VTR Grows Up
The introduction of the VTR was only the beginning.
Over the following few years, Ampex and RCA continued to modify
and enhance their recorders. By 1957 many stations had received
their first VTRs, VR-1000s, with KING-TV in Seattle getting serial
Number 1. (CBS in Hollywood had earlier received the first production
prototype, the VRX-1000.) Both ABC and NBC also received early
It took a while for the VTR to overtake the
kinescope. Stations did not completely trust the new technology
and most engineers were unfamiliar with its complicated circuits.
The kinescope, although crude, was simple and got the job done.
The early VTRs suffered from a number of problems.
Skewing, scalloping, venetian blind effect and incorrect quadrature
became common terms among the new breed of video engineers. As
the industry became aware of the problems, solutions were developed,
one at a time.
One year after the official unveiling of the
VR-1000, a rotary head was shown by Ampex on which the quadrature
could be adjusted and the heads spaced precisely 90 degrees apart
on the head wheel. This cured the major geometric problem of the
early quad machines and allowed tape interchange. It did nothing,
however, for the jitter (timebase instability) problem.
The lack of interchangeability among the very
early VTRs was a serious problem. The same head assembly used to
record a program had to be used for playback. Therefore, the record
machine head assembly had to be shipped along with the tape just
so the program could be properly reproduced.
By 1957, most of the TV industry was using 3M's
Number 179 tape. It was the first commercially produced videotape.
Ampex actually used a prototype of 179 for its 1956 NAB demonstration.
The early tapes suffered from dropouts. At some stations, all incoming
reels were checked prior to use. An engineer would load a reel
of new tape and record black video for the entire length of it,
then watch the entire tape on playback, looking for dropouts.
Compared to kines, videotape was amazingly cheap.
A 1-hour reel of 3M 179 cost approximately $300. Compared to the
many millions spent each year on kinescope film and processing,
the networks would have gladly paid four or five times the original
$50,000 price of the VRX-1000. KING-TV in Seattle, the first local
station on the air with its own VTR, estimated that videotape cut
the cost of recording a program hour from $88 when using film to
less than $3.
Ampex unveiled a modified VR-1000 that produced
color pictures at the 1958 NAB convention. Actors Ronald Reagan
and Red Skelton were the demonstration hosts. RCA followed later
that year with a modification for its VTR to permit color recording.
RCA's first color VTR was called the TRT-1AC. Neither recorder,
however, provided very good color reproduction.
Work continued on ways to tame the rotational
instability of the head, but it was not until the 1960 NAB convention
that a solution to the problem was found. At the show, Ampex introduced
the Intersync head wheel servo that brought timebase errors
down to a peak-to-peak value of 0.15us from the previous peak-to-peak
errors of up to 60-70us. This represented a vast improvement, but
still was not good enough to record and play back color signals
directly. Intersync also allowed several VTRs to be interlocked.
The breakthrough came from Charles Coleman of
WBBM-TV, Chicago, who devised a voltage variable delay line whose
delay could be varied +/-0.5us by means of an error voltage derived
from a comparison of off-tape sync against house (reference) sync.
As a result, timebase errors were reduced to 30ns. Rights to the
device were acquired by Ampex, and Coleman was hired by the company
Thirty nanoseconds was still not good enough
for the long-sought goal of reproducing the color signal directly,
so Coleman and associate Peter Jensen developed time error corrector
that was similar to the Amtec device, introduced earlier.
Amtec was a corrector that removed the jitter and instabilities
common to early machines. The new system had a shorter delay line
and compared off-tape color burst with reference burst to generate
a correction voltage to drive the delay line. Direct color playback
became a reality when the new Colortec system was demonstrated
at the 1961 NAB show in Washington, D.C.
With color recording well in hand, engineers
then turned their attention to improving signal quality. The original
FM carrier frequencies used for recording monochrome signals were
totally inadequate for color. Initially, different frequencies
and greatly reduced deviation were chosen to reduce offensive moire
patterns, however, the reduced deviation made for a noisy picture
and so was not totally satisfactory.
The engineers pushed the state-of-the-art again
and managed to move the carrier frequencies upward from a range
of 5.5 to 6.5MHz to the range of 7 to 10MHz, yielding markedly
The next bombshell development came from RCA
with the 1962 release of the TR-22, the first all-transistor VTR.
The original VTRs required three or more 19-inch racks full of
vacuum tube electronics. A typical machine would employ 160 tubes
and weighed about 900 pounds. From a maintenance point of view,
the solid-state TR-22 was a dream come true. From that point forward,
the technology began to resemble what we see today. Solid-state
components permitted smaller recorders with more and advanced features.
Although the early transistorized VTRs continued to be major maintenance
headaches, the lack of tubes was a real plus.
Helical Format Development
Despite industry acceptance of quad in the late
1950s, Toshiba, in Japan, continued to work on its helical scan
approach to video recording. A company engineer presented a paper
on the concept at the 1960 SMPTE conference in Los Angels, creating
a controversy over the relative merits of basic VTR formats. It
also caused Ampex to rush to completion an ill-fated 2-inch helical
recorder (the VR-8000), which was shipped in heavily constructed,
locked boxes to the following NAB convention in Chicago. Flying
different aircraft, Ginsburg and Maxey had the only keys to the
locks. The VR-8000 was to be demonstrated only if a competitive
broadcast helical recorder was shown. There were none and the black
crates were returned to Redwood City unopened.
In 1975 Fernseh (Bosch) introduced its BCN series
of 1-inch helical recorders at Montreux. Ampex and Sony introduced
1-inch recorders of their own a year later at NAB. All were claimed
by their respective proponents to be suitable for broadcast service,
but all were different and interchange of tape between the formats
was impossible. The Sony and Ampex formats were, however, tantalizingly
similar. All three formats worked well, and it was clear at least
that helical recording had matured.
Several users of recording equipment asked SMPTE
to see if some sort of common 1-inch helical format could be worked
out. During 1977 many SMPTE engineering committee meetings were
held to see what could be done. The Fernseh format was different
enough so that it was defined separately as the B format.
Excellent results were obtained, however, in hammering out the C format,
which was similar to -- but not identical to -- either the Sony
or Ampex machines. In December 1977 SMPTE announced agreement in
principle on the C format, and several manufacturers announced
plans to supply equipment conforming to it. This effort by SMPTE
is a shining example of how the standardization process can work.
By 1958, networks and stations were still using
VTRs primarily for time-delay broadcasts. True editing capability
was not yet a reality. Simple mechanical edits could be performed,
but the process was complex and difficult. The edits were often
jumpy. Even so, CBS aired the first totally VTR-produced program, Playhouse
90, in 1958.
The early editing process required steady hands
and special tools. The video and audio signals were recorded on
different sections of the tape. Therefore, if the audio was important
or dialogue was involved, extra time was required to layback and
resync the audio track.
The required tools included a special microscope
or magnifying glass, a cutting block, magnetic developing fluid
and degaussed razor blades. The tape had to be cut during the video
vertical interval between frames. The early machines often added
special edit pulses in the control track along the bottom edge
of the tape to help identify the possible edit points.
The first step in making an edit was to locate
the proper video point by viewing the tape. Then, the tape oxide
was painted with a special developing solution (Ampex called it Edivue).
The material contained carbonyl iron. The iron powder of the solution
lined up with the magnetic scan lines and the edit pulses. Through
this process, the engineer/editor could locate the vertical intervals
on the tape.
The editing process caused the loss of one-half
second of audio. The missing audio then had to be replaced by re-recording
the audio back on the spliced video tape using a second machine.
This editing process was far from foolproof. Such work was often
referred to as "Kamakazi" editing by the cutters of the
To speed the editing process, NBC in Burbank
developed a method of editing tape by first using a kinescope film
as a work print and later conforming the tape master to the edited
film work print. One of the first television shows to utilize this
technique was the Fred Astaire Special, edited in 1958.
The technique was an immediate success and a flood of television
shows were edited that first year. It was really the first attempt
at what we now call off-line editing.
Physical splicing of tape continued through
the early 1960s, until timecode editing appeared in 1967. Computerized
editing was introduced to the industry in 1971.
The More Things Change...
Few products in this industry have changed more
than video tape recording. The following list contains most of
the video recording formats produced for professional or consumer
uses through the late 1980s:
Sony 2-inch helical
Ampex 2-inch helical
Sony 1-inch helical
Ampex 1-inch helical (type A format)
1-inch IVC (International Video Corp.)
2-inch IVC segmented field helical scan
1-inch type B segmented field (Bosch)
1-inch helical type C
Cartivision consumer cassette format
1/2-inch Betamax consumer (Sony)
V-Cord I and V-Cord II 1/2-inch consumer
VCR and VCR-LP from Philips (those were
the actual names)
InstaVision/InstaVideo (Ampex and Toshiba)
AutoVision VX-100 and VX-2000 (Sanyo)
VHS 1/2-inch consumer
4mm consumer (Samsung)
3/4-inch U-Matic SP
ED-Beta 1/2-inch professional/consumer
Super-VHS 1/2-inch professional/consumer
D1 (component digital, 3/4-inch videotape)
D2 (composite digital, 3/4-inch videotape)
Audio Cartridge Machine
Video products generally capture the attention
of most attendees at the annual NAB convention. However, in 1959
the main attraction at the convention was the first audio cartridge
recorder. Until then, the playback of program material was handled
by discs and reel-to-reel tape decks.
The late '50s was a time of dynamic change in
radio as the industry moved from a medium offering long, discrete
programs to one offering a single, continuous program made of many
short pieces. The rapid-fire, music-and-news format came to be
known as Top 40 radio.
Acetate discs could handle the pace of a Top
40 format, but offered poor fidelity. The lead-in grooves tended
to sound scratchy after several cueings and, after many plays,
the stylus often would jump grooves. Reel-to-reel, on the other
hand, offered excellent fidelity but suffered from loading, cueing
and tape breakage problems. The need existed for a playback system
offering the fidelity of reel-to-reel decks combined with the handling
ease, rapid cueing and instant start of acetate discs.
The audio cartridge machine as we know it was
developed by two stations working in the late 1950s toward the
common goal of devising a better method of playing back commercial
announcements. The stations were WJBC-AM, Bloomington, IL, and
WWDC-AM, Washington, D.C. The WJBC project began as an idea cooked
up by Vern Nolte, general manager of the station, Ted Bailey, chief
engineer, and Bailey's assistant, Jack Jenkins. The three had come
up with the idea of using short-length cartridges for commercial
announcements and having them recue automatically. Design of the
electronics to accomplish the scheme belonged to Bailey and Jenkins.
On January 13, 1959, Nolte wrote to Parker Gates,
president of the Gates division of Harris Intertype, proposing
that the company manufacture and market their cartridge machine.
Three days later, Gates wrote back to Nolte to thank him for the
offer, but Gates explained that his company was already working
on a spot playback device of its own. Gates was, therefore, not
interested in developing a product that would duplicate something
they already had.
The product to which Parker Gates was referring
was the ST-101, better known as the 101 Spotter. Unlike
cartridge designs that used an endless loop of 1/4-inch tape, the
101 Spotter employed a 13-inch wide band of tape on which spots
were recorded side-by-side. An indexed, sliding head arrangement
allowed the user to select any one of 101 spots. Rights to the
machine had been purchased earlier by Gates from Nelson Rupard,
manager of KIND-AM, Independence, KS.
After having been turned down by Gates, Nolte
pitched the idea to Collins Radio. Gene Randolph, then a sales
representative for Collins, paid a visit on WJBC early in 1959.
Bailey and Jenkins told him about their cartridge tape system,
which was then being used on the air to play commercials. As a
former control board operator who had handled countless small reels
of tape for commercial announcements, Randolph saw what a boon
such a machine would be to radio broadcasting.
Randolph returned to the Collins factory in
Cedar Rapids, IA, and told his boss about the cartridge system.
Within 24 hours, John Haerle -- then product line manager at Collins
-- and a company attorney were in Bloomington to work out a marketing
agreement with Nolte.
In a crash program, Collins arranged with Nolte's
newly-formed Automatic Tape Company (ATC) to produce enough cartridge
decks to show at the NAB convention some 6 weeks away. The original
models were designated P-150 (for those having a 15-inch mounting
panel for desk-top use) and the P-190 (for 19-inch rack mounting).
The record amplifier, with a single cue tone, was a separate assembly.
More than a thousand units were sold from the floor of the convention
that year. The purchase price of a record/play system was $945.
A parallel development effort was, meanwhile,
underway in Washington D.C. at station WWDC to develop an endless
loop, automatic re-cueing tape cartridge system. Principals in
the effort were Ross Beville, chief engineer of the station, and
Austin Knox, who had built a crude endless loop machine for background
music applications. The two men joined forces and formed Broadcast
Electronics on June 18, 1959. The company's product was the Spotmaster cartridge
machine. Ben Strouse, who owned WWDC, provided most of the financial
support for the company in the early days.
Although Broadcast Electronics was not incorporated
until after the Collins/ATC machine was introduced at the 1959
NAB convention, company records show that the first Spotmaster
system had been shipped months earlier. So, who was first? It depends
upon who you ask.
The two cart machines were similar in design,
and certainly similar in function. The primary difference was the
automatic release mechanism used on the Collins/ATC system, versus
the manual release mechanism used on the Spotmaster.
Tape Takes Over
After tape cartridge equipment was shown at
NAB in 1959, it became obvious to Gates/Harris Intertype that the
ST-101 was not going to make any significant marketing inroads.
There were several limitations to the system: Announcements could
not exceed 90 seconds in length and, before the next spot could
be selected and played, the tape had to be rewound, similar to
a player piano roll.
The machine was set to automatically recue when
the 90 second limit of tape travel had been reached. Alternately,
the user could initiate a rewind by pressing a front panel switch.
Full rewind of the tape could be accomplished in 22 seconds. A
spot tape index scale was placed on the front panel to allow selection
of the desired announcement. A tape speed of 5 1/2ips was used.
Tape cylinders could be replaced in about 15 minutes, if needed.
Routine exchange of tapes was not recommended, however.
Faced with the competition of the tape cartridge,
Gates began to look for a way to enter the cartridge business.
Between the first showing of the Collins/ATC machine in 1959 and
1966, the partnership of the two companies had been dissolved.
ATC was manufacturing cart machines on its own in Bloomington.
Gates struck a deal with the owners of the company to buy ATC in
1967, and three years later moved the operations to Quincy, IL.
At that point, Jack Jenkins and several other former ATC employees
founded International Tapetronics Corporation (ITC) in Bloomington.
The Gates/Harris Intertype cart machines were marketed as the Criterian line.
The majority of endless-loop tape designs used
the Fidelipac cartridge, whose inventor-patents covered the movable
pinch roller, which eliminated the need to have a roller mounted
inside each cartridge. The Fidelipac drive arrangement was used
in some Viking tape cartridge audio players designed for point-of-purchase
Despite widespread enthusiasm for the new cartridge
system, there were growing pains. One of the major problems was
pressure pad adjustment. If not properly set, the tape audio could
sound muffled or the cue tone could be missed. Any early user of
cart machines can recall countless times when a tape ran past its
cue tone and started playing again, usually over other program
Testimony to the classic design of the cartridge
machine pioneered by Nolte, Bailey and Jenkins at WJBC, and Beville,
Knox and Strauss at WWDC, is the long life it enjoyed.
- Anderson, Charles, "The Progression
of Videotape Recording," Broadcast Engineering, Intertec
Publishing, Overland Park, KS, May 1979.
- Ginsberg, Charles, "The Birth of Videotape
Recording", Ampex Corporation, Redwood City, CA.
- Ginsburg, Charles, "The First VTR: A
Historical Perspective," Broadcast Engineering, Intertec
Publishing, Overland Park, KS, May 1981.
- Graubart, Lawrence, "Magnetic Tape Trends," Ampex
Corporation Magnetic Tape Division, Redwood City, CA.
- Hammar, Peter, "The Birth of the VTR," Broadcast
Engineering, Intertec Publishing, Overland Park, KS, June
- Mullin, Jack, "Discovering Magnetic
Tape," Broadcast Engineering, Intertec Publishing,
Overland Park, KS, May 1979.
- Randolph, Gene, "The History of the
Cart Machine," Broadcast Engineering, Intertec Publishing,
Overland Park, KS, August 1984.
- "Retrospective: The History of Video
Developments," Video Systems, Intertec Publishing,
Overland Park, KS, March 1985.
- Roizen, Joseph, "Video Tape Recorders:
A Never Ending Revolution," Broadcast Engineering,
Intertec Publishing, Overland Park, KS, April and May 1976.
- Schneider, Arthur, "The Growth of Videotape
Editing," Broadcast Engineering, Intertec Publishing,
Overland Park, KS, May 1981.
- Schow, Edison, "A Review of Television
Systems and the Systems for Recording Television," Sound
and Video Contractor, Intertec Publishing, Overland Park,
KS, May 1989.
- Schubin, Mark, "From Tiny Tubes to Giant
Screens," Video Review, April 1989.
- Ziff, Richard, "The 25th Anniversary
of the Videotape," Broadcast Engineering, Intertec
Publishing, Overland Park, KS, April 1981.
This Magnetophone "model K-4" tape
deck is similar to the two machines brought back to San Francisco
by Jack Mullin in 1946. Mullin's machines inspired Ampex
to produce the first successful U.S. professional audiotape
recorder in 1948. (Courtesy of AEG.)
The Great Race to Video Recording
Members of the Ampex videotape recorder
R&D team pose around the prototype Mark IV VTR that changed
TV broadcasting. Shown (from the left) are: Fred Pfost, Shelby
Henderson, Ray Dolby, Alex Maxey, Charles Ginsburg (team
leader) and Charles Anderson. (Courtesy of Ampex.)
The world's first practical videotape
recorder, the Ampex-Mark IV prototype VTR, was unveiled in
April 1956 at the National Association of Radio and Television
Broadcasters (NAB) convention. (Courtesy of Ampex.)
The first broadcast via videotape on November
30, 1956. CBS Television City in Hollywood, shown, replayed
the Douglas Edwards and the News program three hours
after it was received on the West Coast. CBS engineer John
Radis stands at the controls of the Ampex VRX-1000. Note
the racks of support electronics (on the left) for the tape
transport. (Courtesy of Ampex.)
The progress of the videotape recording
from 1953 to 1956. Clockwise from top left: Shirley Temple,
recorded late 1953 using AM signal processing; the Bob Crosby
show, 1954, using FM signal processing; an FM videotape picture
of a kinescope broadcast, mid-1954; and FM recording, early
1956. (Courtesy of Ampex.)
The early Ampex machines required three
racks of tube-filled chassis -- and a lot of maintenance.
(Courtesy of Ampex.)
The RCA TR-22 was the first fully transistorized
VTR. Solid-state technology allowed the complete machine
to be compacted into a single unit 55-inches wide and 72-inches
high. (Courtesy of Ampex.)
Audio Spot Recording
There is some dispute over which company
built the first audio cartridge machine. This Spotmaster
deck is at least one of the world's first cart machines,
built in 1959. (Courtesy of Broadcast Electronics.)
The Gates ST-101 spot tape recorder. The
selector bar on the front panel determined which pre-recorded
announcement was played. The spot playback system was introduced
at the 1959 NAB convention. (Courtesy of Harris.)
Internal view of the ST-101 showing the
magnetic tape cylinder. The roll could be replaced in the
field in about 15 minutes, if necessary. (Courtesy of
Side view of the magnetic tape cylinder
of the Gates ST-101 spot recorder/player. (Courtesy of
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