Best Sounding AM Stations?

[Kelly A]

Indeed the original minimum performance specs for AM were 100hz to 5 kHz but with THD not exceeding 5 %. However, since at least the early 1950s major market stations took pains to make their facilities sound as good as possible, which meant audio with the maximum freq response possible from about 30 Hz to 15 kHz with THD not exceeding 1 % and S/N better that 60 dB.

None of this has been the case for at least sixty three years. Add in the terrestrial noise floor of the Medium Wave band, and it makes current performance of AM even worse. Wax on nostalgic and theoretical all you want. Reality is; AM since the late 60's has been an inferior form of aural media.

Depending on the program material this produces Hi-Fi perfomance in wide band radios. And since the response of most wide band radios max out at just over 10 kHz,

Modern AM audio processors since the 80's start rolling off high frequencies at 5kHz, 8+dB down at 8kHz and a brick wall filter at 10kHz. The reason is to reduce the chances of low pass filter ring. If you can't hear the difference between 5kHz and 12kHz, your hearing is likely degraded.

the fact that the FCC rule change in the 1980s reducing AM audio from 15 kHz to 10 kHz made little difference in these receivers - they still sound good even today.

Again, you're being nostalgic. Compare even your wide band AM tuner with a good quality FM station, streamed, or even by good ol' CD. Reliving your youth is not the same as actual comparative quality.

As I have said on other posts, in general, if your AM sounds bad it usually because your radio sounds bad, maybe like the AM tuner of my Kenwood car stereo: all the stations sound the same regardless of the station's processor settings. The radio's IF bandpass is so narrow that it's hard to hear the letter "s" at the end of spoken words, not to mention significant distortion that's introduced.

Nope, that's a radio nerd wives tale. I worked with Bob Carver back in the 80's while he was developing his AM stereo/FM stereo reference tuner. The test AM stations we used across the country were all over the map in audio performance. The problem with AM, maybe more so than even FM, is the transmission system bandwidth can adversely effect the audio. Old phasors, poorly maintained transmitters, narrow band ATU's, all have an effect. The add in program directors and station owners who insisted on asymmetrical modulation, 124% positive and 99% negative peaks up against the wall, and stereo separation was terrible, and distortion, unacceptable. These are just some of the reasons Bob said the year of R&D on his AM stereo tuner was a complete waste of time.

By the way you mentioned: "people used to think gramophones sounded musical". You have to put this in perspective of the technology of the times, as well as an individual's personal taste. You would be amazed at what a mint condition 78 RPM record sounds like when played through a modern system fitted with a high quality diamond stylus designed for 78 RPM playback...no it's obviously not up to modern standards but it's perfectly "musical" and pleasant to listen to...I have a couple of Glenn Miller records on the original Blue Bird label I found in a thrift store that I discovered had probably never been played (at least not with a "steel needle"). I never though a 78 could be so quiet...

Gramophones are nostalgic, not musical. AM's chance at doing music ended back in the 70's, so call that nostalgic.
I could bang pots and pans together and call it musical. To regular people, it's nothing but noise.

 

[TomásEstefan]

None of this has been the case for at least sixty three years. Add in the terrestrial noise floor of the Medium Wave band, and it makes current performance of AM even worse. Wax on nostalgic and theoretical all you want. Reality is; AM since the late 60's has been an inferior form of aural media.

Modern AM audio processors since the 80's start rolling off high frequencies at 5kHz, 8+dB down at 8kHz and a brick wall filter at 10kHz. The reason is to reduce the chances of low pass filter ring. If you can't hear the difference between 5kHz and 12kHz, your hearing is likely degraded.

Again, you're being nostalgic. Compare even your wide band AM tuner with a good quality FM station, streamed, or even by good ol' CD. Reliving your youth is not the same as actual comparative quality.

Nope, that's a radio nerd wives tale. I worked with Bob Carver back in the 80's while he was developing his AM stereo/FM stereo reference tuner. The test AM stations we used across the country were all over the map in audio performance. The problem with AM, maybe more so than even FM, is the transmission system bandwidth can adversely effect the audio. Old phasors, poorly maintained transmitters, narrow band ATU's, all have an effect. The add in program directors and station owners who insisted on asymmetrical modulation, 124% positive and 99% negative peaks up against the wall, and stereo separation was terrible, and distortion, unacceptable. These are just some of the reasons Bob said the year of R&D on his AM stereo tuner was a complete waste of time.

Gramophones are nostalgic, not musical. AM's chance at doing music ended back in the 70's, so call that nostalgic.
I could bang pots and pans together and call it musical. To regular people, it's nothing but noise.

I have said this before, regardless of the quality of the tuner, you're at the mercy of the radio station. I have never said that all AM radios are bad and that all stations broadcast pristine audio. My only point is that with good tuner and a station broadcasting good audio AM can still sound good and be worth listening to. Next time you're in the LA area listen to the classical music on 1260 KMZT on wide band radio. It sounds good.

 

[cc333]

I'm sort of leaning towards @TomásEstefan 's point of view. It's a given that technologically, AM is quite inferior to FM and Internet streaming in many ways (high noise floor, very suseptible to EMI and other problems, but that doesn't mean it can't still sound good, and it does still have a few advantages (simple receivers and transmitters are relatively easy and affordable to build, long distance reception is fairly reliable)

As for the response of wideband radios, my GE Superadio III, which is wideband sounds really good in wideband mode despite being slightly out of alignment, and when tuned to my Part 15 station (which I can set to a full 20 Hz - 15+ kHz response for experimentation), I can hear frequencies well past 10kHz and it sounds almost FM-like.

c

 

[cc333]

Try and find a Sony SRF-A100. It's a portable AM Stereo/FM Stereo radio. I bought one back in the 80s and still use it today. The AM is dual IF bandwidth, and in the wide band mode it's HI-FI, depending on the station/program material of course.
There is a mode switch on the side of the radio to select between Leonard Kahn's Independent Sideband System (sel "B") and C-Quam and everyone else (sel "A").

I'd like to, but they're kind of expensive.

I blew my radio budget the past few months on a broken Radioshack DX-398 (and the parts needed to fix it), but I'll definitely keep an eye out and try to save up for an SRF-A100, as I do want one eventually. It seems rather silly to broadcast in AM stereo and not have any AM stereo-capable radios, so I'd like to fix this situation (technically, I do have two AM-Stereo radios: the stock systems in our '97 Ford
and '94 GMC pickups).

c

 

[TomásEstefan]

I'm sort of leaning towards @TomásEstefan 's point of view. It's a given that technologically, AM is quite inferior to FM and Internet streaming in many ways (high noise floor, very suseptible to EMI and other problems, but that doesn't mean it can't still sound good, and it does still have a few advantages (simple receivers and transmitters are relatively easy and affordable to build, long distance reception is fairly reliable)

As for the response of wideband radios, my GE Superadio III, which is wideband sounds really good in wideband mode despite being slightly out of alignment, and when tuned to my Part 15 station (which I can set to a full 20 Hz - 15+ kHz response for experimentation), I can hear frequencies well past 10kHz and it sounds almost FM-like.

c

I have one of those GE radios...use the headphone jack to plug it in to your home audio system and it can sound spectacular !

 

[Greg Strickland]

...Modern AM audio processors since the 80's start rolling off high frequencies at 5kHz, 8+dB down at 8kHz and a brick wall filter at 10kHz...

I respectfully disagree. Modern AM processors are specifically designed to process the sound for best achievable high-end in a mono audio path that has a severe de-emphasis in the listener's device. As a result, many AM stations are transmitting plenty of highs right up to 9.5 kHz. Others may be cutting it off at 6 kHz or 8 kHz for a reason.

Modern processors can typically be adjusted to output audio bandwidth of as little as 2.5 kHz to typically 9.5 kHz. Some processors offer a sharp cut-off at the chosen frequency, or a user adjustable roll-off to smooth the cut-off.

My view and opinion:

Stations must comply with FCC rule 73.44, which states emissions 10.2 kHz to 20 kHz removed from the carrier must be attenuated at least 25 dB below the unmodulated carrier level. If the transmitter is clean, 25 dB down is not a brick wall filter on the audio, although most processor manufacturers provide a brick wall filter, to be sure. As perspective, consider that headphones you are listening on might be down 10 dB to 15 dB above 10 kHz.

The FCC rule is looking at radio frequency sidebands on a spectrum analyzer, not audio frequency response. Thus, a station can do whatever it wants with the audio, provided the station runs and documents the required testing, and can demonstrate compliance with the rule if challenged.

It is well known and not a trade secret, that one goal of modern AM processing is enabling a customer to choose making the high end dense, clean and modulating right up there at 85 to 95 percent negative modulation without being trashed by the low end, and vice versa. In FM and AM analog over-the-air broadcasting in the USA, the clipping and back-end process simultaneously seeks density, with minimum distortion and maximum low-end kick, brightness and transient impact, and an absolute peak ceiling. That's a tall order in a business with low sales volume. If a processor manufacturer is interested in a larger consumer audio and podcasting market, they seem to be under pressure to dumb the product down and keep the price low.

Professional broadcasters pay top dollar for the best processing technology in high-end audio processing hardware, for good reasons. They will not go before the audience unless they are sounding their best.

Users can get fine sound with less expensive modern processors, hardware and software, and carefully selected and modified older analog equipment. However, this takes time and dedication, that might be better spent on other tasks. Does a station want an engineer working for 6 weeks on audio, and revisiting it as needed? And even a well-tweaked older system is not directly A-B competitive with a modern top-line processor.

As always, it is a question of what the station owner would like to do. As engineers we are here to help them achieve their goals.

 

[DavidEduardo]

The problem with AM, maybe more so than even FM, is the transmission system bandwidth can adversely effect the audio. Old phasors, poorly maintained transmitters, narrow band ATU's, all have an effect. The add in program directors and station owners who insisted on asymmetrical modulation, 124% positive and 99% negative peaks up against the wall, and stereo separation was terrible, and distortion, unacceptable.

The reason AM music formats lasted much longer in Europe, much of Latin America and elsewhere is that in those places nearly no AM stations were directional. The effects of taking the easy way out of directional system design using high Q networks meant narrow bandwidth and extreme reactance differences at plus and minus 10 kHz resulting in terrible bandwidth.

 

[Kelly A]

I respectfully disagree. Modern AM processors are specifically designed to process the sound for best achievable high-end in a mono audio path that has a severe de-emphasis in the listener's device. As a result, many AM stations are transmitting plenty of highs right up to 9.5 kHz. Others may be cutting it off at 6 kHz or 8 kHz for a reason.

But, modern (post 1988) receivers don't have filters out that far. Sure, there are exceptions like GE Superradio's sold through into 2000's, but few consumers bother actually purchasing radios anymore. And yes, radio nerds can plod-on about 'if only manufacturers would build good radios again, the public would forget their smartphones and buy portable radios en-mass.' The reality is; that day will never come. I still argue; if one can't hear the difference between 8kHz and even 13kHz (typical FM audio low pass), then your hearing has probably degraded due to age. I'm no youngster, but I won't even tolerate listening to music that I knew what it sounded like with the high end rolled off and in mono, when I have so many other higher quality choices. Neither will real consumers. Simple nostalgia from your youth is really what you're talking about.

My view and opinion:

Stations must comply with FCC rule 73.44, which states emissions 10.2 kHz to 20 kHz removed from the carrier must be attenuated at least 25 dB below the unmodulated carrier level. If the transmitter is clean, 25 dB down is not a brick wall filter on the audio, although most processor manufacturers provide a brick wall filter, to be sure. As perspective, consider that headphones you are listening on might be down 10 dB to 15 dB above 10 kHz.

And in modern times, when was the last station you know of that even runs even NRSC bandwidth checks, let alone an annual audio proof?

The FCC rule is looking at radio frequency sidebands on a spectrum analyzer, not audio frequency response. Thus, a station can do whatever it wants with the audio, provided the station runs and documents the required testing, and can demonstrate compliance with the rule if challenged.

And when was the last AM station that you know of who was challenged by the Commission on audio performance or bandwidth?

It is well known and not a trade secret, that one goal of modern AM processing is enabling a customer to choose making the high end dense, clean and modulating right up there at 85 to 95 percent negative modulation without being trashed by the low end, and vice versa. In FM and AM analog over-the-air broadcasting in the USA, the clipping and back-end process simultaneously seeks density, with minimum distortion and maximum low-end kick, brightness and transient impact, and an absolute peak ceiling. That's a tall order in a business with low sales volume. If a processor manufacturer is interested in a larger consumer audio and podcasting market, they seem to be under pressure to dumb the product down and keep the price low.

And also why processor manufacturers stopped R&D on AM processors. There really isn't much else one could do to make improvements to the sound of AM.

Professional broadcasters pay top dollar for the best processing technology in high-end audio processing hardware, for good reasons. They will not go before the audience unless they are sounding their best.

Digital processing technologies have allowed processor manufacturers to eliminate physical components through the use of software. Beyond the cost savings, things like audio performance and upgrades are done without having to completely redesign the device. "Sounding their best" is subjective. There are still too many program directors who want to be louder than their competition, or sound like radio did back in the 80's. It's no wonder why consumers have been migrating toward streaming platforms over the past ten years. Listen to your favorite music via an over-processed radio station, verses an on line stream. The old way of thinking about processing the crap out of music is driving TSL down for what amounts to nostalgia.
AM has a coverage advantage by running asymmetrical modulation, but it also comes at a quality cost. As time has shown; for voice grade, AM is fine, and one can take advantage of asymmetrical audio.

Users can get fine sound with less expensive modern processors, hardware and software, and carefully selected and modified older analog equipment. However, this takes time and dedication, that might be better spent on other tasks. Does a station want an engineer working for 6 weeks on audio, and revisiting it as needed? And even a well-tweaked older system is not directly A-B competitive with a modern top-line processor.

I totally agree with that statement. Anyone who claims an older Orban 8000 or 8100 performs better than a modern digital processor is delusional. I chock that opinion again up to a nostalgic bend.

As always, it is a question of what the station owner would like to do. As engineers we are here to help them achieve their goals.

And many owners/programming/engineering people are in the process, driving listeners away to other forms of music listening.

 

[secondchoice]

I would like to try to turn this tread:.

WSM AM IMHO is the best sounding analog AM I have heard lately.

Are there any AM's that have a music format that are IBOC digital too?

Another question if an AM station goes "total digital" how many 20-15Khz channels can you get? I personally have never worked with AM digital, just wondering if the sales hype is real.

 

[TomásEstefan]

I would like to try to turn this tread:.

WSM AM IMHO is the best sounding analog AM I have heard lately.

Are there any AM's that have a music format that are IBOC digital too?

Another question if an AM station goes "total digital" how many 20-15Khz channels can you get? I personally have never worked with AM digital, just wondering if the sales hype is real.

KMZT 1260 Los Angeles (Beverly Hills)

 

[Kelly A]

Another question if an AM station goes "total digital" how many 20-15Khz channels can you get? I personally have never worked with AM digital, just wondering if the sales hype is real.

WWFD was testing two audio streams from one MA3 carrier. One music 20-15 and one voice grade 50-5. From what I understand, doing the second audio channel eliminated PAD data (artist/title) on the music grade stream, so not sure there would be a benefit.

 

[DavidEduardo]

WWFD was testing two audio streams from one MA3 carrier. One music 20-15 and one voice grade 50-5. From what I understand, doing the second audio channel eliminated PAD data (artist/title) on the music grade stream, so not sure there would be a benefit.

I agree. We just got a new car last week, and unlike my 2015 one that went away, it displays all kinds of data on music. Using Sirius/XM I have photos or album covers on every song as well as more artist/title display. I also get a bottom of the screen pictorial list of "channels I might like" so if a song I do not care for comes up, i can tap or tell the system to jump elsewhere.

I am assuming all new systems are fairly comparable, although in my case it's the audio system of a German brand named after the manufacturer of WW II tanks...

Once you use such a system, not having a full display and options is depressing and old school.

 

[DavidEduardo]

KMZT 1260 Los Angeles (Beverly Hills)

Has anyone listened recently to this one on a car system or radio that has good sound? I have wondered if Sol ever broadbanded the directional system on 1260 because, years ago, it was pretty narrow and the sound did not compare well with better tuned systems.

 

[TomásEstefan]

Has anyone listened recently to this one on a car system or radio that has good sound? I have wondered if Sol ever broadbanded the directional system on 1260 because, years ago, it was pretty narrow and the sound did not compare well with better tuned systems.

KMZT sounds great on wide band receivers, sounds full bandwidth. Saul redid the antenna system years ago, replacing the center "tower" drop cable with a real tower. KMZT is a bit too compressed though but overall not bad...

 

[Kelly A]

KMZT sounds great on wide band receivers, sounds full bandwidth. Saul redid the antenna system years ago, replacing the center "tower" drop cable with a real tower. KMZT is a bit too compressed though but overall not bad...

It would sound even better full MA3 mode..

 

[TomásEstefan]

It would sound even better full MA3 mode..

Of course, but I was referring to KMZT's analog (non HD) sound...