Time to reconsider AM stereo?

[badjef]

AM stereo sounded alot better with Kahn than C-Quam. The range was better hands down. iBOC has advantages but just as with the FM, by the time you get in range for the HD version, the reception for the anologue is more dependable and just as good to the average listener.

C-Quam decision was political in nature. It was not based on technical or listener advantages. Politics trumps everything.

Platform motion along with the dedicated uninterupted pulse requirements made C the 80's version of the HD reception that we experience today.

I picked up WNNNBC in Kahn stereo and after they went C as WFAN. I did a comparision between WRBQ and WSUN. There was no comparision. Kahn was superior in listenability.
Static in Stereo? Yep. Like Sarnoff said...

Go under a bridge, you lose the signal in stereo and mono. With Kahn it stays, C goes away and is percivably annoying listening to it come back several seconds later.

The FCC never wanted AM Stereo. They moved FM and made useless all the receivers of the time.

The marketplace just wants something that is pleasing to the ear. Sometimes that is silence. (ouch!)

Jeff in Sa-ra-so-ta!

 

[HowardMBurgers]

Actually the Magnavox system was the FCC chosen one. When Motorola screamed bloody murder, the Commission threw up their hands and essentially said, fine you decide then. There were few ISB receivers made (not that there were many to begin with), so Kahn was behind the eight ball there too.

Really Kahn never stood a chance of being selected. It was an inferior system by comparrison, especially when it came to specs in an audio proof while used in an average directional night array. The Magnavox system by definition was the superior one, but broadcasters were in three camps: Motorola, Harris (Quasi-Quam) and Kahn. In the end, more were interested in Motorola for ongoing support and likely adoption by receiver manufacturers.

The fact remains that no AM stereo system could attain real world performance results of FM, whether that be S/N, distortion, frequency response, or stereo separation.

 

[RadeoEngineer]

With the Kahn system, you could receive stereo with two analog tuned radios. All you had to do was tune one to the lower sideband and the other to the upper. Voila, stereo!

 

[badjef]

Actually the Magnavox system was the FCC chosen one. When Motorola screamed bloody murder, the Commission threw up their hands and essentially said, fine you decide then. There were few ISB receivers made (not that there were many to begin with), so Kahn was behind the eight ball there too.

Really Kahn never stood a chance of being selected. It was an inferior system by comparrison, especially when it came to specs in an audio proof while used in an average directional night array. The Magnavox system by definition was the superior one, but broadcasters were in three camps: Motorola, Harris (Quasi-Quam) and Kahn. In the end, more were interested in Motorola for ongoing support and likely adoption by receiver manufacturers.

The fact remains that no AM stereo system could attain real world performance results of FM, whether that be S/N, distortion, frequency response, or stereo separation.

The Magnavox choice by the FCC was the first but it was by far not the best system. Kahn was the oldest system and should have been approved 20 years before.

When the FCC made it a marketplace decision, it spoke volumes about its attempt to rid the airwaves of the broadcast band. (Rumour was, at the time, Motorola wanted to use the band for the new Cellular phone system.)

Imagine taking a poll on which TV system people preferred? What reference point do they use?

There were no Hazeltine/Kahn, no Belar, no Magnavox, no Harris receivers. All you had was the Motorola chip.

I had 2 radios I adapted to the Kahn system. I could listen to both systems (C- and Kahn) with the touch of a preset.

There was no comparision Kahn was superior in every way. With directional and non-directional arrays.

The problems with the proofs were with borderline am transmitters. It exposed weaknesses in those operations.

Jeff in Sa-ra-so-ta!

 

[HowardMBurgers]

From your personal listening perspective, perhaps you personally liked Kahn ISB better, but believe me and anyone who actually set up stations with Magnavox, Motorola and Kahn, the audio proof didn't lie. Magnavox was the superior performing system, Motorola a close second, with Kahn the worst at a distant third. Even in ND mode, we struggled to get <18dB stereo separation through a Harris MW-50 50 ohms-J0 at the common point with the Kahn.

In a couple instances, I was on site with Leonard Kahn during installtion of a system. The audio performance went into the tank during night mode on a three tower directional. Leonard wanted to change the phasor to compensate, but we refused. We sent the system and Leonard packing. The only sucessful stations that used a ISB system, were usually ND stations like KSL in Salt Lake. A few weeks later, we installed the Harris system which worked pretty well, (as AM stereo goes anyway)

 

[badjef]

From your personal listening perspective, perhaps you personally liked Kahn ISB better,

From a listener's perspective is where ratings come.

but believe me and anyone who actually set up stations with Magnavox, Motorola and Kahn, the audio proof didn't lie. Magnavox was the superior performing system, Motorola a close second, with Kahn the worst at a distant third.

There were 5 systems, Magnavox dropped out early on after the "marketplace decision" was announced. Harris joined the Motorola camp. I think RCA lost too much money on CED videodisc to take another chance with Belar on the RCA/Belar system.

Even in ND mode, we struggled to get <18dB stereo separation through a Harris MW-50 50 ohms-J0 at the common point with the Kahn.

In a couple instances, I was on site with Leonard Kahn during installtion of a system. The audio performance went into the tank during night mode on a three tower directional. Leonard wanted to change the phasor to compensate, but we refused. We sent the system and Leonard packing.

Sounds as though you had a bad experience

The only sucessful stations that used a ISB system, were usually ND stations like KSL in Salt Lake.

WQXR (Kahn) was a DA with no problem of which I was aware.
WRBQ (Kahn) was a problem for me, but that was co-channel. Next to the station was fine.
WSUN (C-), it was a problem closer to the antenna than WRBQ - day or night.

A few weeks later, we installed the Harris system which worked pretty well, (as AM stereo goes anyway)

Harris gave up their system and made the modifications to adapt to the C-. I can't tell by the post if you installed a true Harris system or not. In any event, Kahn did not give up on the system, he "added" his "Powerside" to the box and tried promoting that while keeping the ISB modulation option in the event the C- was given up on by the stations. The biggest problem was lack of receivers and that was all political.

AM Stereo is/was not a saleable item for the advertiser. There was no ROI for the station owner - but was never tried, either.

Jeff in Sa-ra-so-ta!

 

[wnmb]

Let me jump back into this one more time. Some here have posted that AM Stereo can't compete with FM. This is simply not true. The listener does not care if the specs match exactly. The listener cares that the radio sounds good and he or she gets the fidelity that pleases them in the programming of their choice. In my market, there are about two dozen FM stations and there are just a few of us on AM. WNMB is the only station using AM Stereo. No one here is IBOC. If you think it can't compete technically, I invite you to come to North Myrtle Beach. We have many receivers you can use for your comparison. There's a host of Sonys, Carvers, etc., as well as multiple automobiles. You can listen in a Ford Thunderbird, Ford Explorer, Expedition, and even a new Corvette with one of the Metrosound Stereo converters installed. In every case, unless you're tone deaf, you can tune between WNMB and any FM station here and, in most cases our audio is cleaner, brighter, and better separation. I am not referring to programming....just the technical side of things. As is the case in any radio station, the audio is best when you have a clean and well engineered chain all the way from the console to the antenna. Finally, as I have stated before, the primary problem with AM is today's incredibly cheap and sorry receivers.

 

[badjef]

Let me jump back into this one more time. Some here have posted that AM Stereo can't compete with FM. This is simply not true. The listener does not care if the specs match exactly. The listener cares that the radio sounds good and he or she gets the fidelity that pleases them in the programming of their choice. In my market, there are about two dozen FM stations and there are just a few of us on AM. WNMB is the only station using AM Stereo. No one here is IBOC. If you think it can't compete technically, I invite you to come to North Myrtle Beach. We have many receivers you can use for your comparison. There's a host of Sonys, Carvers, etc., as well as multiple automobiles. You can listen in a Ford Thunderbird, Ford Explorer, Expedition, and even a new Corvette with one of the Metrosound Stereo converters installed. In every case, unless you're tone deaf, you can tune between WNMB and any FM station here and, in most cases our audio is cleaner, brighter, and better separation. I am not referring to programming....just the technical side of things. As is the case in any radio station, the audio is best when you have a clean and well engineered chain all the way from the console to the antenna. Finally, as I have stated before, the primary problem with AM is today's incredibly cheap and sorry receivers.

Here is my quote from another post:

"Increasingly more difficult to pick up, AM suffers from inherent interference from power lines to bridges, from the car's computer to Cuban and co-channel. Inadaquate front-end design and FCC political decisions.

A recent problem with FM interference, I've been experiencing within the last several years is my GPS. It is shortening the range of stations. I imagine that will get worse with more and more gadgets added to the car."

With that said, AM Stereo can compete with FM in concert with programming. Imagine listening to Rush and the Paul Shanklin parody songs in stereo, for example. Your spots will sound better with the stereo dimension even with a new/talk station. WINS was doing that back in the 80's.

However, with a system as finicky as C-, only when the signal is strong will you be able to experience it on a more level field. - just don't tap your horn.

Jeff in Sa-ra-so-ta!

 

[HowardMBurgers]

Let me jump back into this one more time. Some here have posted that AM Stereo can't compete with FM. This is simply not true. The listener does not care if the specs match exactly. The listener cares that the radio sounds good and he or she gets the fidelity that pleases them in the programming of their choice. In my market, there are about two dozen FM stations and there are just a few of us on AM. WNMB is the only station using AM Stereo. No one here is IBOC. If you think it can't compete technically, I invite you to come to North Myrtle Beach. We have many receivers you can use for your comparison. There's a host of Sonys, Carvers, etc., as well as multiple automobiles. You can listen in a Ford Thunderbird, Ford Explorer, Expedition, and even a new Corvette with one of the Metrosound Stereo converters installed. In every case, unless you're tone deaf, you can tune between WNMB and any FM station here and, in most cases our audio is cleaner, brighter, and better separation. I am not referring to programming....just the technical side of things. As is the case in any radio station, the audio is best when you have a clean and well engineered chain all the way from the console to the antenna. Finally, as I have stated before, the primary problem with AM is today's incredibly cheap and sorry receivers.

With all due respect, your case is subjective opinion completely lacking technical merit.

Even in lab environment, AM stereo never even met FM stereo in frequency response, distortion, or stereo separation. Since the NRSC 10kHz HF limits were established, AM audio is pretty much limited to 7kHz of demodulated audio. I'm sorry, if you can't hear the difference between 7kHz and 13kHz in comparison with typical analog FM, I suspect you have suffered hearing damage.

Today add in terrestrial/electrical noise from consumer devices, computers and other switched power supply devices, and the silly thought of AM stereo in a practical sense, becomes even more mute.

Granted the way some FM stations are over-processing and clipping their audio in a MP3 and CD player world is ridiculous; however in an apples-to-apples comparison from a purely technical standpoint, AM stereo never acheived the audio performance and signal to noise ratio of broadcast FM, period.

 

[Chuck]

I think the real question is can AM stereo provide a pleasurable listening experience for the audience? I suspect it can. I distinctly remember hearing AM stereo on a Cadillac factory radio when it came out. I was totally amazed by the sound. It may not have been accurate, but it was very pleasant to listen to. If the content is also pleasant to listen to, then you win. That is all most people want out of radio.

 

[Savage]

"With all due respect," Howard? "With all due respect," your post is obnoxious. It reads like the Goombah from South Philly getting in somebody's face - the old line, "now doan' take dis wrong. Wid all due respect - your sister's a slut, man."

First of all, have a little REAL respect for Bill, an AM broadcaster who's actually trying to do a good job with his station. Second of all, take time to read - and understand - his post before you gleefully try to tear it to shreds. Bill isn't talking about some know-it-all engineer looking at bandpass on a spectrum analyzer or a receiver/scope. He's talking about overall aesthetic "fidelity" - the way real-world people listen to radio, not engineers. If WMNB's signal is pleasing and offers quality appreciated by the average listener in the field does, guess what? Bill's station wins.

I completely appreciate what he means about how well-processed AM C-QUAM stereo is more aesthetically pleasing than today's squash-o-matic screechy FM products. Yeah, I know - so the C-QUAM is 5 kHz narrower on the high end. Who gives a rip if a reasonable person with a reasonable radio thinks the AM stereo sounds great?

Wanna debate bandpass in a hypothetical duel between an AM oldies station and an FM oldies station? Guess what the bandpass of a 45 rpm record was before stereo came out in 1958? Try 5 kHz. So if Bill's C-QUAM signal is up against an FM competitor with the same playlist, what does the additional 5kHz give you other than more noise (and artifacts in the case of digital processors?)

Thirdly: if you're gonna rip into other posters here - and their stations, dismissing Bill's excellent efforts at WMNB as "silly" - you might want to check your useage. The term you want to use in your third paragraph is "moot," not "mute."

Bill's case "is subjective opinion completely lacking technical merit?" You're wrong. As wrong as you were when you declared recently that Kahn-Hazeltine AM stations couldn't pass AM proofs.

 

[badjef]

The marketplace decision was never fully implemented because of Motorola's embed with the FCC. The Sony SRF-A100 was the only radio I know of that had all 5 systems and even at that, the user still had to change the position of the button to receive ISB.

I can't even find another MC-13020p chip.

If it were possible to convince the auto manufacturers to rethink AM Stereo, we might have a chance, but with the current problems existing in Detroit, it would probably be too trivial for them to address, now.

I hope I'm wrong about this.

I loved Kahn AM Stereo when I had it in my car. C- sounded ok but the timing of pulses were a problem but that could have been corrected.

Jeff in Sa-ra-so-ta!

 

[HowardMBurgers]

First of all, have a little REAL respect for Bill, an AM broadcaster who's actually trying to do a good job with his station. Second of all, take time to read - and understand - his post before you gleefully try to tear it to shreds. Bill isn't talking about some know-it-all engineer looking at bandpass on a spectrum analyzer or a receiver/scope. He's talking about overall aesthetic "fidelity" - the way real-world people listen to radio, not engineers. If WMNB's signal is pleasing and offers quality appreciated by the average listener in the field does, guess what? Bill's station wins.


Wanna debate bandpass in a hypothetical duel between an AM oldies station and an FM oldies station? Guess what the bandpass of a 45 rpm record was before stereo came out in 1958? Try 5 kHz. So if Bill's C-QUAM signal is up against an FM competitor with the same playlist, what does the additional 5kHz give you other than more noise (and artifacts in the case of digital processors?)

Thirdly: if you're gonna rip into other posters here - and their stations, dismissing Bill's excellent efforts at WMNB as "silly" - you might want to check your useage. The term you want to use in your third paragraph is "moot," not "mute."

Bill's case "is subjective opinion completely lacking technical merit?" You're wrong. As wrong as you were when you declared recently that Kahn-Hazeltine AM stations couldn't pass AM proofs.

Savage,

I agree with you, Bill's comments are opinions of a supporter of AM stereo, which I respect. Knowing otherwise when incorrect claims are made, I feel the need to comment. It was you who misread the use of the term "silly". My original point, and continue to maintain through actual experience with several AM stereo systems; that AM stereo won't technically compare to the specifications for audio quality of FM stereo, which is one of many reasons that AM stereo was never accepted by consumers or (most) broadcasters.

I suppose there are those on the planet who think old wire recordings sound better than CD's too.

 

[audioguy]

Howard,

If you go back to the very first message where I started this topic, you will find that I expressly acknowledged the fact that AM stereo does not provide audio quality that is equivalent to FM stereo.

On the other hand, at least some people (I am not sure how many; I have not done any research) are satisfied with the low bit rate audio provided by "HD" radio, which in my personal opinion is nowhere near as good as a high quality analog FM system. I have participated in many critical listening tests, and if you have a high quality source to use as a standard of comparison, you can hear the difference immediately.

I agree with Bill that a properly operated AM stereo facility can sound very good, and that many people are more interested in the program content than the audio quality anyway. I also wonder why we are so hung up on stereo separation? Do people care if it's 15 dB or 45? I doubt it. Most recordings don't have that much separation, and most live content doesn't either.

 

[TheRover]

Savage,

My original point, and continue to maintain through actual experience with several AM stereo systems; that AM stereo won't technically compare to the specifications for audio quality of FM stereo, which is one of many reasons that AM stereo was never accepted by consumers or (most) broadcasters.

"FM Stereo" ... Do you mean that over-compressed, over-modulated, brick-walled piece of cr** sound that is now passed off as "FM Stereo" ? ? ?

If so, then I'd really like to try AM Stereo.... couldn't be any worse that that !

 

[Savage]

Trying to identify a single reason why AM Stereo failed is a fool's errand - it's not unlike trying to figure out a single cause of all the the fatal car accidents that occurred last year in the State of Arizona.

It's not as simple as declaring, "FM Stereo won because of its wider bandpass and lower noise." There were many complex interlocking reasons why AM Stereo never flew.

The de facto AM Stereo standard, C-QUAM, was the product of a marketplace debacle caused by the failure of the FCC to pick a single system. There were five systems vying for acceptance, which of course meant they all were doomed to fail. AM Stereo was adopted long after radio audience had largely migrated to FM, so the innovation was kind of like launching a new express fast-embarkation concourse at the local airport to help you catch flights which have already departed. It was too little, too late. Then, there were no receivers (HD, are you listening?? Oh. Right, of COURSE you aren't.) And in the field, AM Stereo operators were unhappy with the comparison of their stereo signals with all-mono competitors. For the C-QUAM system to work the dense asymmetrical modulation practices typical of the 1980s was impossible so stations had to reduce modulation for stereo. Recall that this was a "louder is better" era. For C-QUAM to succeed it should have been made mandatory for all AM stations to level the playing field (which would have achieved a very positive side benefit of generally improving AM sound by forcing an end to "the loudness wars.")

IMHO if C-QUAM had been universally mandated/adopted somewhere around, say, 1972, with all radios required to include AM Stereo from that time forward, AM's fortunes would be greatly improved today. (But that's just the opinion of a self-declared lifelong AM radio fan, and I know it can't be proven one way or the other.)

 

[wnmb]

Today I visited with a prospective ad client. She is a nice lady with a shop in Calabash, which is about 6 miles north of North Myrtle Beach. When I entered the shop I noticed she was playing Easy 105.9 (which is a great station managed by my friend Matt Sedota.) As I introduced myself to her, she said she knew of me and my station WNMB. She liked the oldies and listened sometimes in her car, but she said she never considered playing us in the shop because AM radio did not have the good fidelity of FM. In fact, she said she had tried once to pick us on on the Bose componet system in the store, and she couldn't find us. I looked at the Bose. It did not have an AM antenna connected to its terminals. I asked her to excuse me for a moment and I went to my car and brought in one of the Sony SRF-A100 portables and one of the 80s Radio Shack AM stereo tuners with an antenna attached. I turned on the Sony for her and her eyes lit up. She liked what she heard. Then, I attached the Radio Shack tuner to the auxillary inputs on her sound system and tuned in WNMB. Again, she was pleased with the sound. Did she think it sounded as good as the FM? No. But she thought it sounded great. It was very, very listenable and she liked our music better. (sorry Matt). She made a nice comment about the great stereo separation she heard on the Van Morrison song "Brown Eyed Girl".This true story is to illustrate my point that AM stereo will get and hold listeners if the other necessary elements are in place. You gotta have music or programming the listener likes. You must have a clean audio chain with great processing. To end the story, I left the shop with a six month contract for ads. I left her with the Radio Shack tuner still playing on her system, which she said she would leave on all the time the shop is open.
The moral of the story.......well, I'm not sure except that the AM Stereo works for us. And that's also why I buy a lot those Sony's and Radio Shack tuners on ebay!

 

[badjef]

... And that's also why I buy a lot those Sony's and Radio Shack tuners on ebay!

Now I know who I'm bidding against when I lose a bid on a Sony.

Jeff in Sa-ra-so-ta!

 

[arnoldevns]

I'm going to agree with those who believe that AM's problem is not so much the sound quality, but the programming and reliability of the service at night.

HD-AM does not work. AM Stereo had its shot in the early 80s, but ultimately failed because the protracted process of picking a standard kept most radio manufacturers from making AM stereo radios. By the time a standard had been picked, there was little reason to do stereo on AM since most music stations has switched to talk or gone to FM.

If I had to pick between HD and C-QUAM, I'd choose C-QUAM. Unfortunately, that's a choice that won't really make any difference in the ratings.

 

[badjef]

If I had to pick between HD and C-QUAM, I'd choose C-QUAM. Unfortunately, that's a choice that won't really make any difference in the ratings.

That is subjective and will have the ability of not ever being tried - and why are you so hung up on C-Quam? It was a system designed to fail.

If we could predict everything a human would do, there would be no sense in playing sports when the outcome can be accurately known before it happens.

God doesn't work like that.

Jeff in Sa-ra-so-ta!