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Radio compression?

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Re: Radio compression?

Postby Hugh Robjohns » Tue Jan 08, 2019 10:00 pm

James Perrett wrote:I think the radio mixes over here were mainly to remove/replace any naughty words.

That was definitely a requirement for UK broadcasting (although the list of naughty words has changed over the years). In additioned to the shortened versions you mention, I also know of some cases where special remixes were required to remove extreme phase-shift effects which sounded great in stereo but horrid in mono. Madonna's Vogue is one such that comes to mind!

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Re: Radio compression?

Postby Humble Bee » Wed Jan 09, 2019 3:24 pm

Thank you for all the answers!
Its been very educating.
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Re: Radio compression?

Postby Gone To Lunch » Fri Jan 11, 2019 12:15 am

My Cytomic Glue compressor has a Mastering/Radio Squash preset.

So is that to prepare for radio broadcast, or a guestimate of what a radio broadcast will likely do to the track ?
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Re: Radio compression?

Postby Wonks » Fri Jan 11, 2019 10:31 am

The latter, You don't want your mix really squashed twice over.
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Re: Radio compression?

Postby Mike Stranks » Fri Jan 11, 2019 11:01 am

Wonks wrote:The latter, You don't want your mix really squashed twice over.

Absolutely spot on!

The only time I use Broadcast Process VSTs is when I know what I'm processing will then go straight to air and not be subject to any further processing.
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Re: Radio compression?

Postby ef37a » Fri Jan 11, 2019 11:19 am

Back in about the 70s there was a constant debate about the dynamic range of radio sound, almost exclusively regarding Radio 3 FM. (Hi Fi News, before they all went silly)

The difficulties of a wide DR were acknowledged but many felt the BBC were TOO heavy handed? There was a proposal put several times that the station could broadcast closer to the natural DR but that recievers would have a built in compressor. The quality of the compressor would be reflected in the price level of the reciever. The point was made that very few people would be listening to classical music on a ten quid Curry's tranny!

Dolby B encoding was also suggested.

I have no way to test this but I am sure the peak level on R3 is much closer to the link person's voice than it was some years ago. I was just listening to a violin concerto (via Freeview) and at the end the announcer was close to the loudest the orchestra ever got!
Egmont is playing at the moment and the fffs are certainly not blowing me out of the room.

That might all of course be my deafness!

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Re: Radio compression?

Postby Mike Stranks » Fri Jan 11, 2019 11:22 am

ef37a wrote:Back in about the 70s there was a constant debate about the dynamic range of radio sound, almost exclusively regarding Radio 3 FM. (Hi Fi News, before they all went silly)

The difficulties of a wide DR were acknowledged but many felt the BBC were TOO heavy handed? There was a proposal put several times that the station could broadcast closer to the natural DR but that recievers would have a built in compressor. The quality of the compressor would be reflected in the price level of the reciever. The point was made that very few people would be listening to classical music on a ten quid Curry's tranny!

Dolby B encoding was also suggested.

I have no way to test this but I am sure the peak level on R3 is much closer to the link person's voice than it was some years ago. I was just listening to a violin concerto (via Freeview) and at the end the announcer was close to the loudest the orchestra ever got!
Egnont is playing at the moment and the fffs are certainly not blowing me out of the room.

That might all of course be my deafness!

Dave.

No Dave, you're probably right! :)

ALL BBC Radio stations now use some form of broadcast processing. Obviously it varies from station to station. My totally subjective assessment is that R3 uses far gentler processor settings than Classic FM.
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Re: Radio compression?

Postby ef37a » Fri Jan 11, 2019 11:39 am

Ah! Classic FM Mike. I do flip to them now and again and yes, their average level is a few dB up on R3 but two things really bug me with CFM.

1) Their constant crashing in at the end of a piece before the last note of the piano has died down (and heaven FORFEND we should ever hear a reverb tail!)
I accept the commercial nature and put up with the ads but give us two seconds of recovery PLEASE!
2) The technical properties of the HPF on close up mics seems not to have penetrated? Even the gals have dark brown voices!

This is my experience on Freeview ch 731. CFM is very poor on my car's FM whereas R3/4 is 99.9% solid around the town (repeater top of Eastern Av North) .

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Re: Radio compression?

Postby Hugh Robjohns » Fri Jan 11, 2019 11:54 am

ef37a wrote:The difficulties of a wide DR were acknowledged but many felt the BBC were TOO heavy handed?

i's always going to be a judgement call, but no sensible person would ever want, or could ever tolerate, the actual sound of a full concert orchestra and chorus performing, say, Mahler's 8th in the Royal Albert Hall, replayed with faithful real-life dynamics into their living room, kitchen, or car!

Broadcasting is inherently about compromises. Of course, some compromises are arrived at with more universal support than others... Controlling programme dynamics of a live event is very far from easy, but in general I think the Beeb manage an extremely good job most of the time.

There was a proposal put several times that the station could broadcast closer to the natural DR but that recievers would have a built in compressor. The quality of the compressor would be reflected in the price level of the reciever. The point was made that very few people would be listening to classical music on a ten quid Curry's tranny!

This does seem like a good idea. but it was never going to work with analogue FM transmission systems wit it's inherently restricted signal-noise performance. In practice, what you'd have to do is broadcast a relatively heavily squashed signal to ensure a decent signal-noise-ratio, and then expand -- not compress -- the output for those with high-quality listening conditions to make the quiet stuff quieter, reducing the transmission noise in the process. Essentially, a form of dynamic noise reduction similar to Dolby or DBX. But in the 70s, 80s and 90s, these kinds of systems had quite limited dynamic expansion capability and audible artefacts which wouldn't have kept the HiFi news fraternity happy either. And then there would have been the cost and operational implications of mixing and monitoring to deal with, all of which rendered the idea a non-starter.

However, the advent of digital radio broadcasting with the DAB system provided a transmission path with a much greater inherent dynamic range capability than FM, and the boffins built into it a metadata system which could provide a real-time dynamic control system exactly so that those in good listening environments could hear a more natural dynamic range, and those in noisy environments could have a more squashed version -- with the squash being applied in the receiver itself.

I was party to some early BBC testing of that system in the late 90s, and I know the DAB decoder chips at the time in across the following decade were capable of applying the dynamic range control signal... but as far as I'm aware it's never actually been used in earnest for public transmissions.

I have no way to test this but I am sure the peak level on R3 is much closer to the link person's voice than it was some years ago. I was just listening to a violin concerto (via Freeview) and at the end the announcer was close to the loudest the orchestra ever got!

On Radio 3 the music/voice balances tend to vary a little with the different programme styles, and I would agree that the voice/music balance has evened out a little over the decades, especially in the more 'popular' programming strands. But R3 still has a significantly lower voice level than the other national radio networks, specifically to allow musical crescendos to have proper impact.

I'm listening to Suzi Klein's Essential Classics show this morning and music peaks are hitting hard 6s on my mastering console's PPMs, while Ms Klein's dulcet tones are peaking about 4.5. Most of the (gentle) music is averaging around PPM 3 and there are are periods where the quietest passages don't move the PPMs at all.

This is all from a DAB receiver with the replay level adjusted so that the long time pip on Radio 4 sits on PPM 4.

Switching to Radio 4 (Women's Hour), dialogue is peaking 5.5s routinely and a little hotter now and then, while Ken Bruce on Radio 2 is hitting 6s all the time, as is the music -- but at least the needles are waggling up and down over about an 8dB range, so it's not 'over-compressed'.

Switching (briefly) to Radio 1, the PPMs are pinned hard to PPM6 and move with a dynamic range of about 3dB at most! So it's horses for courses, innit? :-)

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Re: Radio compression?

Postby Hugh Robjohns » Fri Jan 11, 2019 11:59 am

Mike Stranks wrote:ALL BBC Radio stations now use some form of broadcast processing. Obviously it varies from station to station. My totally subjective assessment is that R3 uses far gentler processor settings than Classic FM.

It does... (I find Classic FM very hard to listen too for that very reason, but Mrs R loves it!).

I believe that on R3 the dynamic processing also varies at different times of day and for different programming strands. Most notably, the amount of squash is increased during 'drive time' compared to that employed during evening concerts, for example.

The number of processing bands also differs between radio networks, and the FM transmission paths tend to have different processing settings to the equivalent DAB paths ... although my knowledge of the specifics is now very outdated I'm afraid.

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Re: Radio compression?

Postby Mike Stranks » Fri Jan 11, 2019 1:07 pm

Hugh Robjohns wrote: ... although my knowledge of the specifics is now very outdated I'm afraid.

H

Me too! I used to enjoy the occasions when the engineers at the two BBC local radio stations with which I was involved used to let me venture into the equipment room and talk with me about the various settings on the OptiMod (as it then was) and the other bits of broadcast engineering arcanery. Sadly, over 25 years ago now....
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