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AM Stereo Sound

HadYourPhil said:
I put WODX 1480 and WMIB 1660 on in stereo in May of '99. They stayed that way for a couple of years and sounded teriffic. One of the best AM Stereo stations was WOKY in Milwaukee. On an early 2000's Dod Stratus radio they sounded awesome!

Those Chrysler product radios were excellent AM Stereo performers.
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I had a 1988 Dodge Lancer with the AM Stereo radio it did sound great...can't say as much for the car, but it was a good radio. I still have a Sony Walkman with AM Stereo and a Sony SRF-A100 radio with stereo speakers for AM and FM, switchable between Kahn-Hazeltine and Harris/Magnavox/Motorola systems. Great sounding...when broadcasts were in true stereo.
 
AM Stereo was much like HD radio is today, too little too late. Just like AM Stereo only a few diehard radio geeks knew what it was all about. It took a lot of work to get AM Stereo to sound good. WBT spent a great deal of money redoing their directional array and broad banding their phasing unit. Kahn didn't have as much separation and Motorola had platform motion on distant signals, both had more noise and not as much frequency response as FM.

It did get receiver makers to increase the bandwidth of their receivers and radio stations started working on providing better audio. Yes it sounded good but FM still sounded better. The other good thing was it gave us more program choices as FM became more commercialized.

Just my 2 cents!
 
When I engineered the now-defunct WMMM-AM 1260 in Westport, CT they were operating in Kahn AM Stereo and they sounded fantastic. I have very few recorded airchecks in stereo but I heard the station before and after the implementation of the NRSC-1 mask and AM Stereo can sound fabulous!

I had monitored my station using the Kahn AM Monitor adapter, the Sony SRF-A100, a Sony SRF-A1 as well as a Sony CFS-6000 boombox and the station always sounded great. I think if all the bickering didn't take place regarding which system to use that AM would be in a better place today instead of the dreaded clutter of I-Buzz.

I have a couple of stereo airchecks which I have yet to post but over on the WMMM tribute site I have one of testing the Harris MW-1 transmitter in Kahn AM Stereo using the Mama's and Papa's California Dreamin' - this taped aircheck doesn't do justice to just how good that station really sounded!
 
HadYourPhil said:
I put WODX 1480 and WMIB 1660 on in stereo in May of '99. They stayed that way for a couple of years and sounded teriffic. One of the best AM Stereo stations was WOKY in Milwaukee. On an early 2000's Dod Stratus radio they sounded awesome!

Those Chrysler product radios were excellent AM Stereo performers.
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Yes, I do agree with the Chrysler radios being very "musical" sounding, with a warm low end like a tube set and excellent seperation. I had a 1990 Plymouth Horizon with an AM/FM stereo and cassette unit. One night I tuned into WKBW (1520), the powerhouse out of Buffalo, New York while sitting in my driveway in Bay Shore on Long Island. Clear skywave with hardly any fading. Must have sat there for 2 hours listening to the most sweetest sounding AM I ever heard. I requested a song and the DJ asked where I lived. When I told him how good it sounded, he must have passed it on. Took my phone number and, lo and behold, the station manager called me to verlfy!

Mike S.
Phillipsburg, MO
formerly from Bay Shore, NY
 
Mike Sheridan is right about AM Stereo being "too little too late." I recall a couple of early efforts at stereo. You were supposed to use 2 radios facing each other, tune the first to the left side of the frequency, and the other to the right side of the frequency. This supposedly gave the listener stereo separation.

But who goes to this kind of trouble, when FM is available? By the time true AM stereo had come around, I had abandoned music on AM.
 
Lkeller said:
You were supposed to use 2 radios facing each other, tune the first to the left side of the frequency, and the other to the right side of the frequency. This supposedly gave the listener stereo separation.
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I can't say that I have ever heard of that before, but it doesn't surprise me. In the 90's there were some FM stations in rural Texas that attempted "multicasting" 2 simultaneous high school football games. They would carry one game on the left channel and another game of the right channel. Sucked if you had a mono radio.
 
I think I remember someone on FM doing that either as a joke or stunting before a format change, with different songs or formats on each channel. Weird. ::)
 
Lkeller said:
Mike Sheridan is right about AM Stereo being "too little too late." I recall a couple of early efforts at stereo. You were supposed to use 2 radios facing each other, tune the first to the left side of the frequency, and the other to the right side of the frequency. This supposedly gave the listener stereo separation.

But who goes to this kind of trouble, when FM is available? By the time true AM stereo had come around, I had abandoned music on AM.
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XETRA in Tijuana used this approach in 1969 and 1970. But the idea goes further back.

I didn't know this until recently, but Roger Carroll broadcast his nightly show on KABC in Los Angeles in stereo in 1958 and the months of 1959 he was there before going to KMPC. It was a simulcast on KABC-AM (790) and FM (95.5), with one channel going out over the AM, the other over the FM, and Roger's mic on both. Listeners were told to set an AM radio and an FM radio six feet apart and sit six feet back in the center.

An aircheck exists of Roger doing the show in January 1959 from the L.A. High Fidelity Show at the Biltmore Hotel...and it was recorded (most likely at the remote location or the studio) in stereo. It may well be the earliest stereo aircheck in existence, since the FCC didn't type-approve FM Multiplex until 1961.
 
MarioMania said:
On my Laptop, I want to Mimic the AM stereo sound..Is there a way to do that??

I never had a AM Stereo Radio, Only Mono
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home.earthlink.net/~chrisboone has several CQUAM AM stereo clips from WLS during the BIG89 Rewinds...Remember, AM stereo only has an audio b/w to 10 kHz...where as FM stereo goes to 15 kHz but most people won't notice the difference
 
Actually ... AM stereo can go to 15kHz and beyond. It's the FCC regulations which limited the frequency response to 10 kHz.
Before the NRSC 10kHz FCC mandate, the C-QUAM audio response of (then) WQYK-AM, Tampa Bay went out to 15kHz.
Infinity Broadcasting purchased WCBF 1010AM, Seffner/Tampa in 1987. After a total rebuild of the transmitter site, the station returned to the air on April 1, 1988.
They were a C-QUAM stereo simulcast of WQYK-FM. When I invited the local FCC office to inspect the new transmitter facility, the Inspector (a female) asked whether I had installed the NRSC 10kHz filter.
I told the inspector that I had installed the filter and complained about the restriction of the audio response. I asked if she would like to briefly hear what the full high frequency response sounded like.
She said yes. I switched-out the 10kHz filter for a few minutes. The Inspector was astounded at the fidelity of the AM signal.
After the inspection, I was never again visited by the FCC at the AM transmitter site. C-QUAM can sound very good with the proper processing and a wide, flat antenna system.
 
I think I was pretty fortunate to grow up in Canada in the 80's when rock and CHR were still on AM. I enjoyed all those great 80's hits on some of the best top 40 AM's in stereo and the sound was unbelievable. One day I had one of my classmates over for the first time. I asked him if he ever heard AM stereo before and he said he hadn't but had heard of it. So I turned the radio on, had the button set to mono and told him to put his head dead centre between the speakers...after a few seconds I asked if he was ready he said yes, I pushed the stereo/mono button and he jumped back about 3 feet..then said that was the best sound he had ever heard.
 
One thing I haven't seen mentioned about AM stereo was not only could 2 speakers produce left and right separation, there sounded like there was front and back separation as well.
 
MarioMania said:
What's the diff between C-QUAM and the Khan System?
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The difference is the way the two different stereo signals were modulated. The Kahn system somehow used the sidebands separately; C-QUAM, Motorola, Harris, etc. had stereo systems that had something to do with the phase relationship between the two AM signal sidebands.

To a listener with a radio that would pick up all 4 of the AM Stereo systems (like a Sony SRF A-100), the Kahn system would act like a normal AM signal, the two stereo channels would stay in the same place during fading -- but with the other 3 systems you would hear 'platform' motion at night, if you were far enough from the station for the skywave to kick in -- the skywave makes the two stereo channels move back and forth when the signal fades up and down. If you have headphones on you'll hear the left channel switch places with the right channel, several times a second sometimes.

It's a useful tool for DXing, though.
 
The C-QUAM system used phase modulation for the L-R audio and standard amplitude modulation for the L+R audio.
 
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