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AM Stereo, 50 years ago

B

Big 121

A new console TV/Entertainment center was the newest on the block. An Emerson 19" TV, with stereo turntable, large speakers on each side,
radio ,and "AM Stereo". Well, kind of. This set had TWO receivers; one AM, one FM. The function knob would select AM , FM, or BOTH;
it was called "Simulcast Stereo". It worked like this- simulcast participating stations would broadcast 1 stereo channel on their AM and 1 channel
on the FM. This allowed you to hear broadcast Stereo! KFMB would do this after 6pm nightly, with their 540 and 100.7 stations. Those stations
on an ordinary radio sounded strange with only one "channel" , and this concept quickly died.
This preceded the other AM failures, KAHN-Assymetrical AM Stereo; C-Quam , and HD AM. What's next??
Big 121
 
C-QUAM was hardly a failure.
It was still widely used until HD AM came along and started telling
AM stations that Stereo hurt their signal (it doesn't, but HD AM does).
There are still a few AM Stereo Stations around. WLS still runs it.
There's a site somewhere that lists AM stereo Stations.
 
LibertyNT said:
C-QUAM was hardly a failure.
It was still widely used until HD AM came along and started telling
AM stations that Stereo hurt their signal (it doesn't, but HD AM does).
There are still a few AM Stereo Stations around. WLS still runs it.
There's a site somewhere that lists AM stereo Stations.
Click to expand...

Liberty, I disagree with you!

Hardly a failure?
You've got to be kidding! How do you measure success? AM stereo is the VERY DEFINITION OF A FAILURE. I would place money on being able to find more people who have listened to 8-Track tapes and owned a Betamax video machine than those who have owned an AM stereo. Go to any department store over the last 20 years, when's the last time you saw a radio that had AM stereo on it? And I'm not talking about some specialty electronics store somewhere, I'm talking Target, Kmart, Walmart, Bradlee's, etc. The next AM stereo I see will be the first one. Guess what? I can't say that about HD radio, BECAUSE I'VE SEEN THOSE. Not a lot of them, but I've seen them and at mainstream department stores. The fact that WLS and a few other AM stations still broadcast on AM stereo is not a sign of success. And how about the quality of AM stereo versus AM HD stereo? Horrible! If HD radio is the "tap" heard down the hall, (and LOTS of stations broadcast on HD, yes, even in Lubbock), how could AM stereo ever be anything BUT a failure?

I'm sorry for sounding so harsh.
But, hardly a failure?
Really?


What does this have specifically to do with San Diego radio, again?
 
I have not yet arrived into the 21st century, so I don't have an HD receiver, much less an AM stereo receiver. But wouldn't AM HD have stereo capabilities? Granted, an AM stereo transmitter isn't the same as an HD transmitter and would be useless (I'm guessing really) to an AM broadcating in stereo, but can an AM HD transmitter broadcast a stereo signal, and can HD radios pick up an AM stereo station or an AM HD signal broadcasting stereo?
 
Garrett said:
What does this have specifically to do with San Diego radio, again?
Click to expand...

Calm down there Garrett! AM stereo is part of the San Diego radio history on the antenna skyline.

I still have a couple of AM stereo radios. KCBQ-AM 1170 was in stereo, as was 760KFMB. KFI-AM 640 was in stereo and played music. It did sound great in the car. Both of 'em are Sony radios.

There is a write up on XETRA-AM 690 (or perhaps as XEAK-AM) using an AM stereo based system. There was a plan to have the expanded AM bands be in AM stereo. That was a real success .... NOT.
 
In fact is was originally a REQUIREMENT that extended band AMs be stereo.
That got sidestepped.....
 
The factory radio in my 1993 GMC Suburban was AM stereo. Chryslers were doing the same thing from '88 to '95 or so. There was no labeling on it...you had to actually notice the "STEREO" light come on while on AM or read the owner's manual to know it was there.

It did sound very, very good.
 
San Diego has a unique place in the history of AM stereo as XETRA was the first AM stereo station in the world using a Kahn Hazeltine system. There were no receivers at the time, but you could take two analog tuned radios and tune one to the lower sideband and the other to the upper and receive stereo. Now very few people would actually do this, but I did and it worked.

By the way, KSON AM was also in stereo in 1986 using a Kahn system and KURS went on in stereo using a Motorola C-Quam system.
 
RadeoEngineer said:
San Diego has a unique place in the history of AM stereo as XETRA was the first AM stereo station in the world using a Kahn Hazeltine system. There were no receivers at the time, but you could take two analog tuned radios and tune one to the lower sideband and the other to the upper and receive stereo. Now very few people would actually do this, but I did and it worked.

By the way, KSON AM was also in stereo in 1986 using a Kahn system and KURS went on in stereo using a Motorola C-Quam system.
Click to expand...

You were quite fortunate indeed to hear this. Wish I'd heard it. AM stereo in harmony with the laws of physics must have been beautiful.

For years I've thought about rolling my own home version of Kahn stereo for my part 15, but I hardly have the time to sit still and oh-wow over
space placement of sounds, so stereo's not a priority.

I did love the sound of all the CQUAM I heard, but it's just not the "right" way to do stereo AM.
 
I remember when AM stereo was first being rolled out in the 80's and the only AM stereo radios being sold at Walmart was 2 Sparkomatic car radios. One was a standard radio with the two shafts for volume and tuning, and the other was push button only with a wide/narrow switch. I had one and it sounded pretty good. I don't remember seeing any home radios that had AM stereo on them at most stores. I remember seeing some Sony jam boxes that had it, and Radio Shack used to have an AM only stereo tuner that you could buy. But trying to find an AM stereo was like trying to find a needle in a wood shack. If you were to ask a clerk they would look at you like you were crazy. If you were to tell your friend your deep dark secret that you had an AM stereo you'd get that "You mean you listen to AM radio????" look. Its a shame, because I enjoyed picking up far off stereo from WLS in Chicago and WSM in Nashville at night. The grand old opry sounded good. I once listened to a stereo simulcast of the CMA awards on WSM in stereo on a walkman while watching the TV broadcast with the sound turned down, since our tv station wasn't in stereo. It actually worked pretty good. I bet I'm the only one in the world that did that. Its a shame AM stereo never took off. Nobody really cared and all of the stereo AM stations started to switch to talk so there was no point. Most people don't know it existed.
 
michael hagerty said:
The factory radio in my 1993 GMC Suburban was AM stereo.
Click to expand...

Same with my '89 Chevy Corsica. Undoubtedly why I bought that
particular Corsica, even though I preferred the color on another in
the lot. Had five freq. equalizers rather than bass and treble knobs.

IIRC, it had both narrow/wideband and mono/stereo buttons.

While the Delco got only C-QUAM stereo, I also had (and still have)
a portable Sony SRF-A100 which received all four stereo versions.

Detouring this thread to Phoenix for a minute, I believe "KOOL Gold 960"
(then-sister to KCBQ 1170) was in stereo with its '50s oldies, and at
one point way back then, 55/KOY had a great AM stereo sound on the
Sony--but not in the car as I recall they used the Kahn system (you
flipped the stereo mode switch down on the SRF-A100).
 
oldiesfan6479 said:
michael hagerty said:
The factory radio in my 1993 GMC Suburban was AM stereo.
Click to expand...

Same with my '89 Chevy Corsica. Undoubtedly why I bought that
particular Corsica, even though I preferred the color on another in
the lot. Had five freq. equalizers rather than bass and treble knobs.


Detouring this thread to Phoenix for a minute, I believe "KOOL Gold 960"
(then-sister to KCBQ 1170) was in stereo with its '50s oldies, and at
one point way back then, 55/KOY had a great AM stereo sound on the
Sony--but not in the car as I recall they used the Kahn system (you
flipped the stereo mode switch down on the SRF-A100).
Click to expand...

True. By the time I bought the Suburban, KMYL (1190)'s "Music Of Your Life" was in stereo. Sounded great.
 
They Say The Real Flop of AM Stereo Was the FCC acted on it too late.
By the time they finalized a system AM was already way down. Had They Done It in the
60's or 70's We might still have AM Stereo's today.
 
LibertyNT said:
They Say The Real Flop of AM Stereo Was the FCC acted on it too late.
By the time they finalized a system AM was already way down. Had They Done It in the
60's or 70's We might still have AM Stereo's today.
Click to expand...

A few years earlier wouldn't have hurt, but the FCC really dropped the ball by not type-approving a single system...instead allowing "the market to decide". That resulted in three AM Stereo systems totally incompatible with each other and no receiver capable of decoding more than one of the three.

The shakeout took years and by the time the dust settled, not enough people were still listening to music on AM for it to matter.

If the FCC had moved no earlier, but chosen a single system, I think it would have made a difference.
 
LibertyNT said:
They Say The Real Flop of AM Stereo Was the FCC acted on it too late.
By the time they finalized a system AM was already way down. Had They Done It in the
60's or 70's We might still have AM Stereo's today.
Click to expand...

Not so simple. The FCC designated a system in the 80's then Leonard Kahn went ballistic trying to overturn the decision because they didn't pick his. He was successful in getting the FCC to back up and "let the marketplace choose." Now you had competing, noncompatable systems running and receiver manufacturers didn't know what to build, except Sony who built a few models that could receive any of the systems, but required listeners to know how to set the switches, which also required them to know what system was being used by a particular station. Ugh. So the battle was on and the expense to install was fairly high. As has been noted in earlier posts a few car manufacturers included C-Quam AM stereo receivers but many broadcasters stayed away, especially those already into news, sports and/or talk. I ran Kahn on KSON-AM but I installed a C-Quam system (don't remember which one) on KURS. They both sounded good but most people never heard it. Eventually the Kahn system literally burned up so KSON went back to mono and stayed there. Not one call from a listener came in.

I don't know that wide spread adaptation of AM stereo would have really done that much for the band. There are enough FM's to cover every music format and as good as AM stereo can sound it still can't match the noise level of FM nor can it match the frequency response.
 
RadeoEngineer said:
....as good as AM stereo can sound it still can't match the noise level of FM nor can it match the frequency response.
Click to expand...

Amen - rather I like putting lipstick on a pig. I remember when I first heard about the proposal for AM stereo and thought, "Well there's a solution in search of a problem."

Now do think that it digital AM would have been cool: while I don't know what kind of bandwidth could be supported, it does seem like a way to overcome the traditional shortcomings of the AM radio, which is basically still using 100+ year old technology. Since we don't have Western Union telegraph operators anymore, I would venture to say that AM is the oldest communications technology in use today and you have to wonder how many decades it has left. If you follow broadcasting news it's fairly common to see AM stations going dark because it makes no economic sense to run them anymore. I used to be a shortwave listener and it's interesting how how little activity there is now in the traditional international broadcasting bands. The whole radio spectrum below about 80mHz or so seems to be becoming a radio desert.
 
oldiesfan6479 said:
55/KOY had a great AM stereo sound on the
Sony--but not in the car as I recall they used the Kahn system (you
flipped the stereo mode switch down on the SRF-A100).
Click to expand...

Correct. By the time I got there, the Kahn exciter was used to prop open a door in engineering.
 
RadeoEngineer, two qeustions, please-
1. Approx when did KSON use the Kahn system?
2. When was the "old" 440' tower installed?
Thanks!
 
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