View Full Version : FM radio stations - what do they use to play audio?


idem
04-10-12, 03:25 PM
The FM radio in my car (and it is a standard VW CD/radio player) does sound good, actually very good. So the question is: what sort of equipment radio stations use to play audio? Any info?

TLS
04-10-12, 05:07 PM
Good FM can beat cd and vinyl but no one seem to know why.

Tw99
05-10-12, 01:21 AM
Surely it doesn't really matter what they use to play the music, since whatever the source is, it'll almost always go through a heavy compressor before it gets broadcast so there's no dynamic range.

dweezil
05-10-12, 01:44 AM
Certainly beats internet radio, no dropouts and i think we have a better frequency range.
I'm on a vintage Yamaha tuner with only a dipole aerial although i can see the transmitter.

Used to be pretty respectable with a roof aerial too when we used Crystal Palace transmitter about 80 miles away; Capital Radio was good.

Presumably the Beeb use multiple sources

Joddle
05-10-12, 02:04 AM
Good FM can beat cd and vinyl but no one seem to know why.

I have noticed on many occasions that on live broadcasts on FM the quality can be outstanding - but when a recording is played later of the same thing it is often very disapointing in comparison. Somehow FM radio is able to convey a "realism" that a recording seems not to have. The odd thing is it starts and ends at the same places - ie the recording mic and the listener's loudspeaker - its the bits in between which seem to make the difference.

johnhunt
05-10-12, 02:23 AM
Certainly beats internet radio, no dropouts and i think we have a better frequency range.
I'm on a vintage Yamaha tuner with only a dipole aerial although i can see the transmitter.

Used to be pretty respectable with a roof aerial too when we used Crystal Palace transmitter about 80 miles away; Capital Radio was good.

Presumably the Beeb use multiple sources

Capital radio good?

JTC
05-10-12, 02:29 AM
Could it just be the compression?

MJS
05-10-12, 02:37 AM
Could be the compression, pre-emphasis, modulation, stereo encoder...
It's truly capable of stunning s/n ratio, for example hearing the aircon in the studios on R4 - but not yesterday's 'Today' programme in which case you'll have heard it in the kitchen above a washing machine.

JemHayward
05-10-12, 02:40 AM
Compressed music in the car sounds very detailed, as it pushes certain things forward in the mix, and you can therefore hear things easier than you can at home on a decent system... but, its not hifi.
Radio 3 is capable of stunning quality, especially on live music, but try listening to it in the car, you can't hear anything useful.
I don't use FM at home any more, as the 320bps Radio3 via the 'net, for me, is good enough, though I did listen to FM at a friends house recently, and was stunned how good it sounded via her Naim tuner and ancient 32/160 system. If I listened to Radio 3 a lot, I would probably go back to FM.

stevec67
05-10-12, 03:38 AM
In the past they had very high quality turntables of the Garrard and EMT variety, later replaced by heavyweight CD players, now computer audio. Amplifiers traditionally were Quad 50E or similar, no foo, no 400 power cables, just quality items. I suspect they simply assembled it properly and got on with it.

PaulMB
05-10-12, 04:04 AM
From what I understand, FM transmission rolls off from around 16 Khz. (please correct me if I'm wrong) This might give an impression of "body" "smoothness" and general pleasantness to the listener, compared to the often metallic timbre of a CD played at home. In other words, in a sense it plays worse but feels better.
Or am I talking rubbish?

Alan Sircom
05-10-12, 04:13 AM
The FM radio in my car (and it is a standard VW CD/radio player) does sound good, actually very good. So the question is: what sort of equipment radio stations use to play audio? Any info?

Ignoring the compression system (because that's already been done), the BBC's radio service today is mostly run through a VCS dira! system. The front end looks a little like a DOS version of iTunes meeting an Excel spreadsheet and combines an asset management platform with full content management of music, speech, indents, etc, etc. And it allows a lot of server logging. There is some provision for old-school (vinyl, carts, even MD carts) but most of the music you hear on radio is entirely HDD based.

The content itself will be in BMF, a broadcast variant of .WAV that allows extremely robust metadata application and can be reliably ported across the widest number of digital audio workstation (DAW) options. That way, if BBC Radio Upper Dicker turns out to have a steam-powered studio, it will still be able to play audio files sent from the Salford overlords.

Most broadcast services of any reasonable size will have something similar, if perhaps not as 'Big Brother Is Watching You' as the Beeb's fully integrated ENPS (electronic news production system) platform.

dweezil
05-10-12, 04:48 AM
Capital radio good?

You want to try the local offerings on the Essex and Suffolk borders.

All downhill since we lost Caroline.

Tenson
05-10-12, 04:58 AM
How does all the HDD music get to the transmitter? I heard many still get piped through an old 14-bit DAC.

MJS
05-10-12, 05:33 AM
From what I understand, FM transmission rolls off from around 16 Khz. (please correct me if I'm wrong) This might give an impression of "body" "smoothness" and general pleasantness to the listener, compared to the often metallic timbre of a CD played at home. In other words, in a sense it plays worse but feels better.
Or am I talking rubbish?

Not talking rubbish, you need to tune out the 19kHz pilot tone and many cassette decks would have had an MPX filter to prevent any modulation with the biasing. A good tuner will have decent filters on its output that notch out the 19k pilot tone but still keep the HF.

14-15kHz bandwidth is typical.

Alan Sircom
05-10-12, 06:12 AM
How does all the HDD music get to the transmitter? I heard many still get piped through an old 14-bit DAC.

That's very likely in some places. The revenue stream for analogue radio transmission isn't that deep or fast-moving these days.

sergeauckland
05-10-12, 06:15 AM
How does all the HDD music get to the transmitter? I heard many still get piped through an old 14-bit DAC.

Rather depends on the network, but the general principle is that from the output of the studio desk, it goes to a transmission router, which selects which studio is being sent to air, then goes into a codec of some sorts which digitises the analogue audio using some lossy algorithm like APT-X and onto the digital network. It's then picked up at the transmitter station, goes into the Air-processor (Optimod, Omnia or similar) and into the transmitter itself. BBC Network radio are slightly different in that the Optimods are at Broadcasting House as part of the London Control Room, and they distribute processed audio out to the transmitters rather than processing at the transmitter. It's a lot more cost-effective doing it that way when there are a lot of transmitters involved.

BBC NR are also different in that their desks are digital, and output at 44.1kHz sampling for radio (48k for TV) into the digital transmission router. The DAB, D-SAT feed is sample-rate-converted from 44.1 to 48k, whilst any News feeds which may come from the TV side is sample-rate-converted to 44.1 for radio use.

S.

mr_phil
05-10-12, 06:39 AM
Very interesting and informative thread, thanks all. Yes the sound quality is often / usually surprisingly good considering all the messing around with the signal but personally I wouldn't invest in FM today as DAB(+) is clearly unstoppable. I use internet + iplayer and think it is fine - not a R3 listener though

Phil