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!

[Bill]

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.