FM radio : Source Quality and type Related Querries

[drkrack]

I have been listening to FM stations since quite few years.
I like the old bollywood songs quality whenever they are playing on FM, especially All India radio. Though the details are not as glaringly evident as much as the home stereo; but the musicality and Non fatiguing nature keeps me longing for more. The same song played on Cds on Marantz CD player or my previous Vinyl Gear (which was way better than Cds for bollywood oldies) haven't been able to match up. I understand that there are quite many variables involved in car vs home stereo listening, but I firmly believe that there's some uniqueness to FM transmission.

As far as my previous knowledge goes, its the uncompressed Analog that is streamed via FM radio. Frequency modulation has a maximum limit of 15khz if I remember correctly. Is it the same format being used still now? How about newer titles, are the analog versions being used? Or digital sources getting converted to analog in studio and streamed? If so, what kind of DAC the FM stations use? How much the EQ adjustment done in the studios?
If FM transmission imparts a certain SQ advantage, Can we set up a local FM transmission at home to reproduce the same kind of quality to be reproduced at a different place throughout the home?
Any info is valuable
Thanks

 

[Naturelover]

@sam9s should be able to guide you here. Meanwhile check out this thread.
https://www.hifivision.com/threads/...t-powered-by-synology-413j-and-icecast.48913/

 

[sam9s]

As far as my previous knowledge goes, its the uncompressed Analog that is streamed via FM radio. Frequency modulation has a maximum limit of 15khz if I remember correctly. Is it the same format being used still now? How about newer titles, are the analog versions being used? Or digital sources getting converted to analog in studio and streamed? If so, what kind of DAC the FM stations use? How much the EQ adjustment done in the studios?.
If FM transmission imparts a certain SQ advantage, Can we set up a local FM transmission at home to reproduce the same kind of quality to be reproduced at a different place throughout the home?
Any info is valuable
Thanks

Your queries can be answered, by someone who knows how the FM station is run. naturelover suggested my name probably coz I ran my own Radio Station for 4-5 years from my house at some point of time, but that was not FM, that was online radio.
I am not sure your objective of the query you have placed here, but what I know is ......... FM is still analogue, but the source I am sure now is digital. So the conversion must be happening .... what kind of DAC is used and EQ adjustment only someone who is working in an FM station can tell. But I am 100% sure some kind of compression must be happening before it's been broadcasted and my guess is max 96kbps.

Can we setup local FM transmission ??........ well for listening inside a car where only you will be the logged listener, its pretty easy and I am sure you must know. A good Fm transmitter will be able to transmit CD quality over short distance easily. Problems come when you increase the distance or logged in users..... then Fm signal will be prone to static and humming.

If you are thinking about a professional FM radio station, then the story is altogether different.

But an online Radio is a much better easier option to set up, you can have a much wider reach. (in comparison of Home based FM station) I can share the thread where I have shared the project I did .... for 4-5 years I kept it working online .... but now it offline for maintenance, plus I wanted to change the hardware to a much lesser power footprint, so I might start it again ....when I myself don't know ...

https://www.hifivision.com/threads/...t-powered-by-synology-413j-and-icecast.48913/

 

[drkrack]

Can we setup local FM transmission ??........ well for listening inside a car where only you will be the logged listener, its pretty easy and I am sure you must know.

Yes a similar solution which we use inside the cars in the olden days (for stock head unit without USB ports, we used this hack) , can that be extended to a house of 3000 sft?

But an online Radio is a much better easier option to set up, you can have a much wider reach.

No, I'm not looking to set up an online radio station or a professional FM station. I'm enquiring on possibility of using frequency modulation technology for enhancing the local listening experience.

Yes anyone with the experience of working in a FM station should chip in and be possibly able to guide me better.

 

[smedhavi]

I was also missing the soothing/non-fatiguing sound quality of old bollywood songs on Vividh Bharti/AIR playing all day on the valve radios in my childhood. These stations still sound a lot better than the private FM stations. I am sure they still have some songs on analog sources, whereas the private FM channels have a highly compressed harsh sound quality. Over the years I found the Denon cartridges DL 102 (mono) and DL 103 (stereo) that were designed for, and used by, analog radio stations. These cartridges playing through tube electronics (Phono+Pre+Power) on single full-range speakers have got me a lot closer to the sound I was looking for.

Regards,
Sharad Medhavi

 

[jls001]

As far as my previous knowledge goes, its the uncompressed Analog that is streamed via FM radio. Frequency modulation has a maximum limit of 15khz if I remember correctly. Is it the same format being used still now? How about newer titles, are the analog versions being used? Or digital sources getting converted to analog in studio and streamed? If so, what kind of DAC the FM stations use? How much the EQ adjustment done in the studios?
If FM transmission imparts a certain SQ advantage, Can we set up a local FM transmission at home to reproduce the same kind of quality to be reproduced at a different place throughout the home?
Any info is valuable
Thanks

15 kHz bandwidth is correct.

FM in India is analog.

Compression happens in two ways in analog FM broadcast : first, the Studio-Transmitter Link is either a 2 Mbps leased line, or a backup dial up 128 kbps ISDN line. Codecs used for coding the audio signal use different proprietary compressions. Secondly, the FM modulation itself limits the audio signal to about 15 kHz.

Content is certainly digital and playback/scheduling is computer based.

EQ happens at the transmitter. They use very advanced audio processing to tune the sound of the station.

 

[sam9s]

Yes a similar solution which we use inside the cars in the olden days (for stock head unit without USB ports, we used this hack) , can that be extended to a house of 3000 sft?

Yes why not you need a good, long range high-quality FM transmitter .... something like below (Not vouching for the quality of said product, just saying you need something like this, search more before ordering .. )

https://www.amazon.in/Signstek-Broa...YCL1nKgDHvaDI2KDiXG2Ok99NwHZyBmwaAlmtEALw_wcB

 

[smedhavi]

I'm enquiring on possibility of using frequency modulation technology for enhancing the local listening experience.

You could surely use FM modulation to cut some cables, but don't expect it to "improve" the sound in anyway! It could remain the same (at best), or get worse. If you find the roll-off at 15+KHz pleasing you could achieve it in easier ways. I am a bit confused on what you are aiming to achieve with this exercise.

 

[drkrack]

Denon cartridges DL 102 (mono) and DL 103 (stereo) that were designed for, and used by, analog radio stations. These cartridges playing through tube electronics (Phono+Pre+Power) on single full-range speakers have got me a lot closer to the sound I was looking for.

That's a good info, I believe AIR should be maintaining first copy vinyls of bollywood oldies at least.
My idea of using FM technology is cutting the cables and the digital glare, if that soothing SQ is the property of FM transmission. I know with everything in audio, its not that simple. I also want to know any other FMs experimented in this regard already!

Compression happens in two ways in analog FM broadcast : first, the Studio-Transmitter Link is either a 2 Mbps leased line, or a backup dial up 128 kbps ISDN line. Codecs used for coding the audio signal use different proprietary compressions. Secondly, the FM modulation itself limits the audio signal to about 15 kHz.

Content is certainly digital and playback/scheduling is computer based.

EQ happens at the transmitter. They use very advanced audio processing to tune the sound of the station.

thanks, Just Limiting the freq above 15khz doesn't give similar results, so the proper audio processing might be the secret here. The audio processing may not be "live" for music I guess, the presets for each track might be predecided and applied automatically, unlike the RJ voices which might be processed live. Any idea what kind of brands and actual components involved? A digital to analog conversion without absolutely Nil digital glare is quite attractive in itself. Many of the newer titles may not be available in analog I think.

 

[prem]

AIR uses cds for oldies. They don’t have any vinyls

 

[smedhavi]

Try a non-oversampling, filter-less R2R DAC sometime.

Regarding digital equalization to achieve the sound you may be looking for cut 2KHz to 4KHz by 3dB, and taper down 1KHz and 5KHz by 1.5dB. Try it live first, then regenerate the files with the final equalization applied. You may want to boost 400/500Hz by a couple of dBs depending on your speakers and equipment.

 

[jls001]

That's a good info, I believe AIR should be maintaining first copy vinyls of bollywood oldies at least.
My idea of using FM technology is cutting the cables and the digital glare, if that soothing SQ is the property of FM transmission. I know with everything in audio, its not that simple. I also want to know any other FMs experimented in this regard already!



thanks, Just Limiting the freq above 15khz doesn't give similar results, so the proper audio processing might be the secret here. The audio processing may not be "live" for music I guess, the presets for each track might be predecided and applied automatically, unlike the RJ voices which might be processed live. Any idea what kind of brands and actual components involved? A digital to analog conversion without absolutely Nil digital glare is quite attractive in itself. Many of the newer titles may not be available in analog I think.

See this page for the variety of broadcast processors available. I don't think stations switch audio processor settings for voice and music. They use only one. Most processors have very nice presets that one could use but some stations choose to create their own "curve".

And this is a popular codec brand. We know them more by their consumer brand APTX bluetooth. They are essentially compression guys.

More than the fact that you like listening to old Bollywood on FM, you probably like old Bollywood per se. Here's a test: do you also like the sound of modern Bollywood on FM but don't like the same current Bollywood when you play from a CDP? If the former, then FM is the magic ingredient.

 

[smedhavi]

AIR uses cds for oldies. They don’t have any vinyls

You have accurate information most of the time, so I would I believe you.
I got confused by the better quality and the dust/scratch sounds I hear sometimes on Vividh bharti. Also that some AIR stations seem to list a good number of LPs in their library:
http://allindiaradio.gov.in/Station/CHITRADURG/Pages/default.aspx

Library facilities​

A. Discs​

• LP- 1088
• EP-252

http://allindiaradio.gov.in/Station/PASSIGHAT/Pages/default.aspx

a) Discs (LP records) 3322 Nos​

 

[prem]

Smedhavi, as far as I know they don’t use vinyls. They may be having them in stock. That I wouldn’t know.

Also most AIR stations have the original first press Bollywood film cds which were made in England. Many of these cds were directly mastered from vinyl with no noise filters. I have in the past owned almost all of them. They total over 500 in number. In many of them you will hear some hiss and some minor pops or tics like you do in vinyl playback

Your best bet for old Hindi Bollywood is either these made in England cds or the original first or second press vinyls. Anything else is a waste of money.

 

[smedhavi]

Your best bet for old Hindi Bollywood is either these made in England cds or the original first or second press vinyls. Anything else is a waste of money.

True. I have the latter for most stuff I care about. I had a few England made CDs. I also got the UK pressings of a few LPs and I was impressed. Then started wondering if my firy pressing LPs we're good enough for other movies

 

[prem]

I am very curious. Which UK vinyl pressings of Bollywood films do you have. Other than a couple of compilations and a couple of films I have never seen UK vinyl pressings of Bollywood films

 

[smedhavi]

I am very curious. Which UK vinyl pressings of Bollywood films do you have. Other than a couple of compilations and a couple of films I have never seen UK vinyl pressings of Bollywood films

One example:
https://www.hifivision.com/threads/vinyl-i-am-listening-to.4689/page-204#post-718686

 

[prem]

This one I have seen Smedhavi. Other than this I have seen two more compilations and a pressing of Mother India

 

[spirovious]

Similar thread you can refer to-
https://www.hifivision.com/threads/dac-systems-used-for-fm-radio.21852/

Once l also asked a RJ about it and he said they use PC and a mixer connected to it.Rest technical aspect he couldn't tell.