What is the AM music "sound", besides mono?

[alexis]

Howdy!

There's an AM music station whose playlist I'll listen to, I'm very familiar with the songs, and I notice that for the first few minutes of listening after switching from an FM music station that it sounds very ... different, and I don't think I mean the mono vs stereo thing.

I don't know how to describe the AM music sound compared to FM beyond the mono vs stereo difference, but some words that come to mind are "congested, like there's a veil over it, hard to hear vocals, like there's something missing ...".

Is there something in AM technology that makes it unavoidable for music to sound like that? I've listened to other AM music stations to compare, but I am not familiar with the songs hardly at all, so I don't know what's missing (if anything) compared to if I had heard them in stereo/FM.

Interestingly after a few minutes of listening have gone by I get accustomed to the AM music station, and it all sounds just fine to me ... I don't get it!

Thanks for any education you might want to send my way ... anything will help, I'm sure!

[MarkOne]

The biggest difference is obviously the bandwidth.

AM stations have a maximum bandwidth of around 5KHz.

[amanise]

The biggest difference is obviously the bandwidth.

AM stations have a maximum bandwidth of around 5KHz.

.. So would that mean that the AM stations would have to use different compression settings? Compression colours radio sound a lot if you listen to speech on something like BBC Radio 4, and then on BBC Radio 1. Comparing speech really shows that music stations are very compressed. I don't know if this translates to whole wavebands though.

[Hugh Robjohns]

Yes, very limited bandwidth, with a very steep low-pass filter at around 4.5kHz. Often the bass is dialled back too, in the receiver if not the transmitter.

So it's a very mid-forward sound inherently, and then usually compressed and limited heavily. This is partly because AM is prone to interference and fading effects, but it's also to maximise the transmitter coverage area.

In many cases that (multiband) compression is set up to give the station a recognisable 'sound character'.

[alexis]

Thank you MarkOne, amanise, and Hugh!

Yes, very limited bandwidth, with a very steep low-pass filter at around 4.5kHz. Often the bass is dialled back too, in the receiver if not the transmitter.

So the hippies in their teens and twenties years old who were listening to their AM transistor radios heard the same sonic quality as they're able to hear now, as a result of age- related high frequency hearing loss!

I can see why it was so important to buy the album in those days of AM radio. It must have been completely mind blowing to hear the music as the engineers and producers intended after initial listens on AM radio ...
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So it's a very mid-forward sound inherently, and then usually compressed and limited heavily. This is partly because AM is prone to interference and fading effects, but it's also to maximise the transmitter coverage area.

Like free NS-10s?
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In many cases that (multiband) compression is set up to give the station a recognisable 'sound character'.

That is amazing ... it dragged the listening experience even further from what the producer and engineer wanted people to hear!

Very educational, thank you, Hugh!

[amanise]

I remember being totally mind blown the first time I heard music on good headphones as opposed to my rinsed old Dancette record player. Symbol bell strikes blew me away. I heard some percussion for the first time in the Count Basie orchestra. Karen Carpenters voice just leapt out in all its colour and I couldn't stop listening to it. Instantly hooked on the detail of it all - but someone had put it all in there to start with in the studio - deliberately

[MarkOne]

after all my early teens listening to Radio 1 (247M of course) on an old valve Marconiphone 'wireless' and then on a tiny transistor radio, my records on my parents (Bush probably) auto changer record player with it's single 7" elliptical speaker, the pinnacle of audio quality for me was the system they had at the local youth club (also valve), but all of 30W with a pair of 18 speakers wired in parallel - no tweeters of course!

So can you imagine, aged 16 the impression our neighbours 'proper' hifi - Big floor standing Heathkit 3 way speakers, an Amstrad series 60 preamp and power-amp combo and a Garrard AP76 and Shure cartridge.

I mean by any definition of real HiFi, none of this was high end. But, I can honestly say that afternoon changed my life forever.

[adrian_k]

I had a similar experience, I was used to hearing music on either the Murphy TV or a Chinese portable transistor radio. Our (rich) neighbour built a stereo hifi system, I’ll never forget hearing it. Big band jazz on floor standing speakers, it did something good to my brain.

[BWC]

So the hippies in their teens and twenties years old who were listening to their AM transistor radios heard the same sonic quality as they're able to hear now, as a result of age- related high frequency hearing loss!

Any worse than what their grandkids are hearing through their crappy little built-in phone speakers? A little more high end, a little less low end, still pretty crappy sounding.

That is amazing ... it dragged the listening experience even further from what the producer and engineer wanted people to hear!

"Broadcast processing" is still a thing (even for internet broadcasting). Sometimes I go flipping through the "music" channels on Plex. The ones provided by Vevo are definitely not concerned about "what the producer and engineer wanted people to hear!" "Vevo 70's" is a good bit louder than both "Vevo 80's" and "Vevo 90's", for example.

[alexis]

So the hippies in their teens and twenties years old who were listening to their AM transistor radios heard the same sonic quality as they're able to hear now, as a result of age- related high frequency hearing loss!

Any worse than what their grandkids are hearing through their crappy little built-in phone speakers? A little more high end, a little less low end, still pretty crappy sounding.

Good point!
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That is amazing ... it dragged the listening experience even further from what the producer and engineer wanted people to hear!

"Broadcast processing" is still a thing (even for internet broadcasting). Sometimes I go flipping through the "music" channels on Plex. The ones provided by Vevo are definitely not concerned about "what the producer and engineer wanted people to hear!" "Vevo 70's" is a good bit louder than both "Vevo 80's" and "Vevo 90's", for example.

I knew "broadcasters" changed the compression on things nowadays, for a variety of reasons. I wonder if they are also messing with EQ as part of "adding their station's sonic signature".

[amanise]

I got sent a link to the hours' audio output in which my tracks featured from that internet radio station I ended up being played on the other week, so I took a look at it out of curiosity. Nerding on number 11, I loaded it straight into RX. What I saw was a shock. I thought my tracks had sounded quiet - but the waveforms were shocking. My tracks were sandwiched in between fairly simple stuff (acoustic guitar and singer type stuff). These were pumped up to at least -7 LUFS integrated. In between were my tiny but carefully crafted to no more than -14 integrated LUFS tracks - still with their dynamics - but peaking no louder than the presenters speech. Confusingly, there was no discernible distortion on the pumped stuff, but my efforts did sound a bit puny alongside. It's a rock god's nightmare! Punified by acoustic guitars!

[BWC]

I wonder if they are also messing with EQ as part of "adding their station's sonic signature".

Undoubtedly. ...some of them anyways.

It's a rock god's nightmare! Punified by acoustic guitars!

So, I guess that tells us that they were respecting the producers' visions. ...and that many such visions are still corrupted by all the loudness propaganda.

[alexis]

...My tracks were sandwiched in between fairly simple stuff (acoustic guitar and singer type stuff). These were pumped up to at least -7 LUFS integrated. In between were my tiny but carefully crafted to no more than -14 integrated LUFS tracks - still with their dynamics - but peaking no louder than the presenters speech ...

Back then I listened to the presenter leading into your song(s?) ... sorry, can't remember the details, but big picture is it/they sounded just fine, not too soft.

I also listened to some of the other songs, but not long enough to have one of them, the presenter, and yours played in the same listening session, so I can't comment on whether yours sounded softer than the other songs.

Overall, I didn't come away with any negative impressions about your volume!

[amanise]

....

Overall, I didn't come away with any negative impressions about your volume!

I remember a distinct feeling of needing a more impressive cod piece.

[alexis]

....

Overall, I didn't come away with any negative impressions about your volume!

I remember a distinct feeling of needing a more impressive cod piece.

It's all in the attitude!

[Drew Stephenson]

I just took a grab of the version of Gridlines that went out on BBC introducing last week and they'd not taken any liberties with the loudness at all. Which was nice.

[BigRedX]

So the hippies in their teens and twenties years old who were listening to their AM transistor radios heard the same sonic quality as they're able to hear now, as a result of age- related high frequency hearing loss!

I can see why it was so important to buy the album in those days of AM radio. It must have been completely mind blowing to hear the music as the engineers and producers intended after initial listens on AM radio ...

It depends what you were using to listen to your vinyl. For the longest time all I could afford was a Dansette that cost me £8 from a junk shop in the mid-70s. It was mono but one channel of the stereo pair was considerably louder than the other so in some ways the AM broadcast of the music was superior to what I heard when playing the record.

[Jay257]

Something we take for granted now but when I was growing up I still remember the thrill of hearing something for the first time in 'studio quality' and in stereo after years of hearing it on an AM radio station.

Not the records of course as you could buy those, but in later years hearing the jingles from stations such as Luxembourg, RNI, Caroline, Mi Amigo and of course Radio One in their pre-FM era.

The biggest revelation was listening on headphones for the first time to a Switched on Bach CD. Suddenly, out of nowhere came the sound of RNI's news jingle. I didn't know they'd pinched it from Wendy Carlos's epic.

As for AM bandwidth there was a short time in the summer of 1978 that Radio Mi Amigo seemed to be sounding much better than usual, I think they had tinkered with some filtering and were radiating a signal wider than the usual 4.5kHz. Fortunately my radio didn't chop off the excess.

And was it true that the loudness wars actually had their origin in the days of jukeboxes?

The playback volume was fixed, so the record labels would battle it out to see whose records could sound the loudest.

[Nazard]

There are still a lot of AM shortwave stations about, though fewer than previously:

https://swling.com/blog/wp-content/uplo ... -24-v2.pdf

And the BBC still do some shortwave broadcasting which you may hear, depending on propagation and your antenna.

https://www.bbc.co.uk/programmes/articl ... requencies

Longwave is a different story:

"On a positive note, the BBC has delayed its planned closure of longwave transmissions until at least March 2025. This is because the 'radio teleswitching' signal broadcast inaudibly on longwave is still required to switch heaters on and off, due to a delay in the role out of 'smart meters'. The BBC has said that it is likely that Radio 4 Longwave will continue to broadcast during this time."