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what years did they do am/fm split stereo?

ke4mcl

ke4mcl

Super Member
Banned
im trying to figure out how old a tuner i have is. its a philco standalone tube tuner that looks like it was part of a highend console. it has separate am/fm sections that can operate at the same time for split stereo. i know they only built these for a couple of years but what where those years?

i'll be posting pics and a thread about the resto project later tonight.
 
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It was a 1958 thing mostly, I am not sure of any other year more than another ie:57, 59.


Carl
 
Any links to historical documents regarding this would be appreciated (e.g.
newspaper ads for stereo broadcast concerts, flyers from radio stations, etc.).
AM/FM stereo sets of this kind were manufactured in Canada as well, I wonder
whether such transmissions were done in this country.
 
This topic came up in the Tube forum yesterday. I can confirm that my 1960 Fisher console had a tuner B input for achieving the AM / FM stereo signal.
 
My Fisher TA-600 (58) and Stromberg Carlson SR-445 (~60) are binuaral.
The Scott 300 (57-59) 330 (55-56) 330D (60-62) and 333B (64-65) were binaural.

The McIntosh MR 66 has binaural capabilities and was made from 60-61.
 
The other day I spotted a Trio receiver that has dual AM bands: one on the right, one on the left, but both are clearly labelled AM. If I recall correctly, that LD about the history of Pioneer that Madpioneer posted links to here recently, also mentioned a dual-AM receiver they made, for a broadcast in Japan... or was that also AM/FM?

FM with multiplex is common enough.
AM/FM dual band are fairly rare.
AM/AM dual band I've never seen in the flesh until this Trio, and possibly (if I remember right) the one in the video.

A year ago, I would have bought the Trio for "the collection", but I'm not out to build a museum and am trying to de-clutter, so... I did NOT get it. It's still there, AFAIK, if anyone craves it.
 
Offhand, I'd say from the late 50's until the advent of FCC approved FM stereo in 1961. Once that happened these evaporated like the morning dew on a hot summer morning.

While not a definitive reference, scanning through these catalogs will give you a pretty good idea of it's availability to consumers : http://www.radioshackcatalogs.com/

I had a Fisher 101-R (in the 1959 catalog) and it had this feature along with an output for an anticipated FM multiplex adapter. Sort of an early attempt at obsolesce proofing.
 
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1957-1964! Essentially obsoleted by the FCC legalizing FM Stereo in 1961. The Zenith-General Electric multiplex system was selected by the FCC as the US standard. HH Scott was the first to have FM Multiplex tuners and FM Stereo multiplex generator equipment available for this system still in use today. That's right, HH Scott at one time made broadcast equipment (mainly FM Stereo generators and FM monitor and Relay tuners)
 
I am aware of the history of modern stereo broadcasting, as well as of the
existence of earlier attempts at using simultaneous AM and FM channels with
tuners receiving both modes at the same time. What I would like to see is
examples of published radio schedules or program advertisements for
such AM/FM stereo broadcasts. Thanks for any useful info.
 
Actually, I think the first equipmen in use for broadcasting was from Sherwood per the information from them at the time. While the literature as not specific it would infer the company would also have worked on the MPX decoder in order for it to mate with the broadcast equipment used in the trials. Scott's claim to fame I believe was the 1st tuner with integrated mpx, something Sherwood was actually late to the game with as a standard product. Sherwood stayed with mono tuners with an outboard mpx and an accessory add-on internal mpx.

The time-line does seem about right.
 
I find it interesting that the MPX circuit was on a small sub-chassis in most early to mid 60's stereo tuners, receivers, and radios. This would make sense for tuners that were designed before the standard was approved, but you would have thought the next year's models would have fully integrated the MPX circuits.
 
The companies would need time for licensing the circuits from the patent holders, then do their own engineering and production setup. Also, there would be the re-engineering of the production line and unit electrical layout to accomodate the onboard mpx. Also, going onboard would require new power supply on the tuner. This all takes lead time. additionally, the market was larger for the outboard mpx units as for some years manufacturers were hedging their bets as to the system that would win by adding an output provision to allow the tuner to be modded to accept whatever system triumphed. While we think about am-fm stereo and mpx as the competing systems, I seem to remember there were a couple of others in contention. With thousands of tuners out there already set for conversion there was a larger marker for the converters sooner than for mpx included tuners.

Plus at the time, stereo mpx was not a guarented winner. Many were still pooh-poohing stereo and mono system sales were still quite large. It was during this period that convertible intergrated amps and preamps were around. A rather unsettled time but really fun as regardless of the final fallout, the customer was going to have better sound.
 
andy said:
I find it interesting that the MPX circuit was on a small sub-chassis in most early to mid 60's stereo tuners, receivers, and radios. This would make sense for tuners that were designed before the standard was approved, but you would have thought the next year's models would have fully integrated the MPX circuits.
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With the the solid-state era on the horizon, they probably weren't in any great hurry to modify existing tube designs.
 
KentTeffeteller said:
1957-1964! Essentially obsoleted by the FCC legalizing FM Stereo in 1961. The Zenith-General Electric multiplex system was selected by the FCC as the US standard. HH Scott was the first to have FM Multiplex tuners and FM Stereo multiplex generator equipment available for this system still in use today. That's right, HH Scott at one time made broadcast equipment (mainly FM Stereo generators and FM monitor and Relay tuners)
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I believe SHerwood was also instrumental in designing and supplying some of the first SM Stereo Broadcast Equipment.
From http://www.geocities.com/frleand/ClassicAudio/Pages/Sherwood.html

Edward S. Miller, Sherwood's general manager watches as Chicago FM station WKFM owner throws switch for first FM stereo multiplex broadcast along with background multicasting. Sherwood supplied the equipment.
(June 18th, 1961
 

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Yes, Sherwood was an early supplier of FM Multiplex equipment. HH Scott supplied tuners to the FCC FM Stereophonic committee and made decoders for each of the proposed systems. HH Scott already had technical data and expertise early on on FM Stereo. Sherwood's FM Multiplex equipment wasn't built in very many numbers. Many early FM Stereo stations had HH Scott equipment for Stereo broadcasting. I have a few old transmitters in standby with Scott MPX generators. They sure make fine Stereo but are finicky these days to keep at peak performance. Mainly Collins FM transmitters paired with these (1960-1964 era)
 
Here’s an excerpt from a cool little book I found titled The Story of Stereo: 1881- by John Sunier, written in 1959 and published in 1960 (before the FCC’s decision on multiplexing was handed down in 1961). Though Sunier’s prose can be hard to follow, it covers the subject of "Stereocasting" in depth from the prospective of someone present at and focused on the early years of modern stereo.

Stereo Broadcasting in the 1920’s

F. M. Doolittle describes the work of an American radio station experimenting in stereophonic broadcasting in 1925:

“Considering the fidelity with which the present broadcasting apparatus transmits the frequencies employed in music, it may not appear reasonable to expect that any marked improvement is either necessary or possible. [Sic!] Certain factors besides tone values must, however, be taken into consideration. The phonograph and the radio loudspeaker have educated the ear to believe that a close approximation to true tone values is really all that can be expected, and hence the listener does not expect an exact reproduction. Reproduction, using the word in its strict sense, would, of course, mean a rendition so nearly identical with the original that one would be unable to tell, without bringing into play other faculties than that of hearing, whether or not he is present at and listening to the original performance. A close approximation to such reproduction is possible with the method here to be described.” [F. M. Doolittle, “Binaural Broadcasting.” Electrical World, April 25, 1925]
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The station was WPAJ, at New Haven, Conn. Since it was already broadcasting on 227 meters (1320 kilocycles), an additional wavelength assignment of 270 meters (1110 kc) was secured in order that binaural transmission might be possible. Duplicate transmitters were installed. Two standard broadcast microphones of the time were connected, one to each channel, with a seven-inch separation between their centers. The transmission was not impaired for ordinary reception since the same program was heard on each wavelength. If binaural listening equipment was used, the naturalness of reproduction was reportedly startling. Headphones were found to be essential, since loudspeakers mixed up the sound from the two separate channels and impaired the effect. Although little publicity resulted from the project, Doolittle says that a number of experimenters were told how to install equipment for binaural reception. He found the new listeners were, without exception, enthusiastic in their acceptance of the new method of broadcasting.

Doolittle used two antennas to radiate the two waves. He said it was possible to operate the receivers from a single antenna also. The major difference was the use of two tuning adjustments and two detectors instead of just one of each. Further experimentation showed interesting effects. If the microphones were placed 6 to 7 inches apart, a normal impression of the size of the studio and location of performers was gained. If the microphones were moved farther apart, an impression of greater depth was obtained and the performers seemed to recede. However, if the microphones were moved still farther apart, the binaural impression became very vague and was eventually lost altogether.

“Binaural transmission also produces an apparent increase in volume. If switching arrangements are provided so that the headset may be quickly shifted from the usual or monaural reception to binaural reception, sounds which are heard will appear to jump to their respective locations in three dimensions, and simultaneously there occurs an increase in volume . . . it is not difficult to imagine that an interference effect of some kind is produced by subjection to abnormal phase relations.” [F. M. Doolittle, “Binaural Broadcasting.” Electrical World, April 25, 1925]
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Doolittle also discovered some of the advantages that stereocasting provided the performers. He described the many phase relationships that exist in a complex musical performance, some direct and some reflected. In monaural broadcasting, the reflected sounds create unpleasant hollow effects and the studio must be draped to prevent reflections. The resultant deadness confuses the performers. With binaural broadcasting, the reflected sounds convey an impression of the general surroundings. It is then unnecessary to provide damping and the performers like the more natural room tone, finding it much easier to perform.

A few American radio stations conducted experimental two-channel broadcasts at this time. Radio was in its infancy and not many people owned the two sets necessary for listening to stereocasts. So the pioneering work of WPAJ was almost forgotten and stereophonic broadcasting lay dormant for many years.

AM-AM

This system of broadcasting, described above, has not been popular in this country since the 1920’s due to its poor use of the spectrum. The system needs two entirely separate AM radio channels or, in other words, two separate radio stations. Since the AM band is already so crowded [1959] and spectrum space at a premium, this is wasteful. Also, FCC regulations forbid the owner of one AM station to own another AM station in the same locality. The cooperation of two separate AM stations brings up many problems of a commercial nature.

AM-FM

This system employs two stations, as does the AM-AM type, but it is considerably more economical because many AM radio stations also broadcast simultaneously on FM. The job of feeding one audio channel to the AM transmitter and the other channel to the FM transmitter is quite easy. The listener places his FM receiver on the left, tuning it to the FM channel, and his AM channel receiver on the right, tuning it to the AM channel, and after placing himself about 1-1/2 times the distance of the separation of the two radios, enjoys stereo sound.

Many AM-FM stations have been experimentally broadcasting stereo programs by this method since shortly after World War II, when FM came into new prominence. More than 100 stations in the country now [1959] use it intermittently.

Disadvantage of AM-FM

The biggest disadvantage of this method is the widely different quality of sound of the two channels. FM reception is clear, wide-range and undistorted, while AM reception is muddy, noisy and of greatly limited frequency range. It is as though one were listening to a stereo record on which the left side of the groove was a modern LP disc with a quiet surface, and the right side was a worn, ancient shellac 78-rpm record.

FM-FM

This method is a step in the direction of higher-quality stereocasting, but still contravenes the FCC requirement that the frequency spectrum be used in the most efficient manner possible. The sound quality it produces, when two FM stations which have cooperated for the broadcast are of similar power and characteristics, is superb. Even the best of the multiplex systems fails to achieve the frequency and dynamic range of this method. However, it is very difficult to arrange for two entirely separate FM stations to cooperate on a broadcast that only a tiny minority of listeners will be able to hear in stereo. For, while many listeners own both an AM tuner or radio and an FM tuner or radio, very few possess two FM sets. The combination of an FM table-model radio with an FM tuner and and hi-fi system is as unbalanced as the AM-FM setup, and the second matched FM tuner or receiver could be expensive. Therefore, an extremely limited number of FM stations cooperate for this venture at stereocasting.

TV-AM or TV-FM

This method has so many disadvantages that it is difficult to understand why even a small number of stations and two of the TV networks have attempted it. The sound channel of the television station, which is really also FM, carries one of the two audio signals. The other signal is carried either on a separate FM or separate AM station. The listener then places the radio set 8 or 10 feet to one side of the TV set and tries to balance the sound coming from the two sources. Even with the TV-FM method, this is difficult, for TV sound is notoriously bad.

The most annoying part of this type of stereocasting is that, if TV alone is desired, the sound heard is only one half of the program unless the listener goes to the bother of setting up an AM or FM radio on one side to receive the second channel. In addition, the television viewer not owning an AM or FM set would be forced to accept only about half the sound of a program that he wanted to both see and hear.

Three-channel TV and FM Radio

A solution to the last problem has been tried by several groups. WGBH-TV, Boston’s educational channel 2, presented several three-channel sound transmissions beginning on April 4, 1958. Boston’s University’s station WBUR-FM broadcast the left microphone signal, WGBH-FM broadcast the right, and the television sound carried the pickup of the center microphone. When the placement of the three channels, two FM and one TV, was duplicated in the listener’s home, the stereophonic reproduction was better than with two-channel methods. Since the center microphone picked up a balanced overall sound from the musical groups, a viewer listening to only the television broadcast received a high-quality monophonic signal.

WCRB, in Waltham, Mass., cooperated with television station WHDH in Boston for another three-channel TV and radio program. The program was a special Disneyland show on the life of Tchaikovsky, with scenes from Walt Disney’s film “Sleeping Beauty.” A three-channel feed was provided by the ABC network. WCRB-FM carried the left-hand signal, WHDH-TV carried the center, and WCRB (AM) the right hand signal. The picture was seen on WHDH-TV.

Survey of Stereocasting Activity

While the alterations over multiplexing continued, broadcasting stations around the world merrily devoted thousands of hours to stereophonic broadcasting of the two-separate-channel variety, until something better came along.

World leader, as far as amount of stereocasting goes, seems to have been Boston’s WCRB. The station programmed 40 hours of AM-FM stereo per week over its twin transmitters. Station president Theodore Jones believes that “FM’s future lies with the AM-FM stereo operator,” and the station certainly demonstrated what it preached. Stereocasting began in 1954 for about 4 hours per week. The stereo tapes used were mostly produced by WCRB, beginning with Choruses of New England. The early Cook stereo discs were also used.

The library at WCRB included some 400 classical commercial stereo tapes, 200 WCRB-produced tapes and hundreds of the latest stereo discs. Regular live stereophonic concerts began with the 1957-58 Saturday evening stereocast of the Boston Symphony Orchestra, and continued with the following season of Boston Pops concerts. These were followed with the delay stereocasts of the 1958 Berkshire Music Festival at Tanglewood, Mass. Among the other stereocasting “firsts” at WCRB have been these:

(1) First in New England to broadcast stereo discs.
(2) First to present a regular series from stereo tape.
(3) First to present opera in stereo.
(4) First radio station to combine with TV for stereocasting in New England.

Another of the more than 125 stations that did stereocasting was WQXR in New York City, owned by the New York Times. Long known as the “Good Music Station,” its chief engineer claims WQXR’s AM signal reaches 15,000 cycles if the receiver is good enough to pick it up. This results in a much better balance with the FM channel in stereocast.

WQXR’s interest in stereocasting goes back to Oct. 29 and 30, 1952, when the first broadcasts of stereo tape and live music were made in connection with WQXR-FM. As with most of the AM-FM methods, the FM station broadcast the left channel at 96.3 mc, while the AM station broadcast the right channel at 1560 kc. A year later, WQXR was broadcasting nearly all of its live programs stereophonically. To guard against the two channels being too dissimilar and spoiling signal-channel reception, tapes and discs are carefully auditioned beforehand. The station had a permit for multiplexing before the FCC by AM-FM simulcasting.

The stations of the State University of Iowa in Iowa City did some of the earliest stereocasting in the United States. The first live stereo broadcasts were made in 1948, shortly after the installation of FM station, KSUI. The new transmitter was paired with AM station, WSUI, for the stereo broadcasts. Live concerts are now being recorded in stereo for future broadcast on WSUI-KSUI. Choral music had been wisely chosen for the first tape-recorded stereocasts due to the thrilling stereophonic effects possible with human voices in chorus.

WCBS in New York City broadcast the 1958 Newport Jazz Festival in AM-FM stereo during July, but they compromised the signal so greatly for the benefit of single-channel listeners that it was difficult to tell if the broadcast actually were two-channel.

Another FM-AM station situated in Iowa has been broadcasting in stereo regularly for almost 4 years. The first stereocasting activities of WOI and WOI-FM took place in December, 1955. The occasion was the Christmas presentation of the Messiah by the Iowa State College Orchestra and Chorus. The microphones were spaced about 30 feet apart in front of the orchestra, dividing the stage approximately into thirds. A second pair of microphones stood about 3 feet apart directly in front of the soloists in the chorus. The results were gratifying and obtained the enthusiastic cooperation of members of the Music Department faculty who had objected to the presence of two “unsightly” microphones where one had stood before.

Two Minneapolis stations, KUOM (AM) and WLOL-FM, engaged in stereocasts each Saturday afternoon for an hour and a half. WUOM, University of Michigan, offered an explanation for the absence of stereo programming in their program guide. It typifies the attitude of many stations not entering stereocasting at this time:

“...why is it that more stations have not converted to stereo broadcasting?...First, the stereo techniques applied to recording are new, and many years have been spent in perfecting this process. Second, there is still considerable disagreement among broadcasters and engineers as to the best method of stereo broadcasting. Third, the FCC had not yet approved, except experimentally, any system of stereo broadcasting...
To achieve...compatibility, WUOM engineers have been studying the (Crosby system). This system is now being experimentally used... WUOM has, in addition, studied some of the other methods for stereo broadcasting, and found them wanting, particularly as to compatibility...
And where does WUOM stand? Conversion of its transmitter and audio facilities will be an expensive procedure, and necessitate careful planning and experimentation. Until we are satisfied that we will not sacrifice quality to our many listeners with their present equipment and still offer good stereo quality, we will not convert the station...” [WUOM Monthly Program Guide, Nov. 1958]
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Also, consider then that with FM stations, their subcarriers (SCA) made their money until around the middle 1970's. Any proposed Stereo system which didn't allow for SCA would have harmed FM Station profitability. Most public radio stations still use their SCA channels for Radio Reading Services for the disabled.
 
I have noticed in Sam's Photofacts that it was the convention to refer to tuners which could receive both AM and FM broadcasts simultaneously as "FM-AM" and those that couldn't as "AM-FM". Perhaps the "FM-AM" reflects the FM carrying the left channel and the AM carrying the right. I have also tried to figure out when the earliest dedicated, all-in-one-chassis "FM-AM" simulcast receivers were made available to the public. So far, it seems to be the H. H. Scott 330(A) which debuted in 1955 according to this site.

I might have to look for one of these for my collection - what a great looking tuner!
 
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