“Don’t kill your sound over that last dB of loudness” is good advice for stations that want to sound both clean and loud as well as increase their Time Spent Listening.
In this second article of a series about audio signal processing we meet Orban’s competitor Omnia. The processing brand, founded by Frank Foti, is part of the Telos Alliance. At IBC 2013, I’ve met Omnia developer Leif Claesson who created the Omnia.9 and also co-founded the Claesson Edwards broadcast audio company.
“See which processor your competition is using”
Reverse clipping and distortion
“It’s hard to find current music that doesn’t have clipping nowadays”, Claesson says about the common problem of over-processed songs. Omnia tries to neutralize distortion with a de-clipper and a multiband expander, which together form the Undo function – like a ‘Ctrl Z’ for sine waves of which the top has been cut off in the music industry’s loudness war and now has the form of a square, rather than a round wave. We’re listening to a completely distorted heavy metal song that, after we press ‘Undo’, sounds much cleaner indeed. The Omnia.9 remote control screen shows that the original, heavily compressed waveform – as it was ‘mastered’ by the record company – is reshaped. It looks like all clipping has disappeared, and even more importantly: that same track actually sounds much more powerful now.
The Undo function algorithm is able to figure out which part of the signal is missing, and then re-create it, based on frequencies that came before and after. The multiband expander ‘sees’ where audio is dynamic, and where it’s not – in which case it will be adjusted. “Without this”, Leif Claesson continues, “I wouldn’t be able to listen to music. At least not any audio mastering after 2002, when things started to get really hay wired.”
Review output after processing
Omnia.9 includes a complete modulation analyzer. “It allows you to compare what the signal processor sends to your transmitter to what you get back from the transmitter over the air, which ideally should look the same. It also helps you to see which processor your competition is using.” Claesson puts the FM broadcasting frequency chart of an Omnia.9 besides that of a competitors’ flagship product. “It’s very easy to tell which processor is which.” He demonstrates that the Omnia audio processor’s frequency graph (big picture above) “goes down very sharply and protects the pilot tone” and that the other sound processor’s fingerprint shows “composite clipping artifacts around the pilot”. This monitor tool also allows him to assist clients remotely. “You can connect the composite output of a tuner to the Omnia.9’s composite input. If a station needs help with, for example, beating their competition’s sound, I can dial in from wherever I am to see and hear what they’re doing locally.”
“Airplanes have never crashed because of radio
in the two loudest cities in the world”
Introduce market-wide MPX Power
You work with many stations around the world. Do you see global audio processing trends?
“In countries that have MPX Power, the loudness wars have ended. ITU-R BS.412 is a very interesting standard for limiting the modulation and loudness in radio.” He explains that in the past, radio stations only had to limit their peak modulation to +/- 75 kHz from the assigned FM frequency. It was tempting to crank up the processor and continuously stay at 75 kHz in order to sound louder than others, until broadcast engineers found an interesting way to put this on the agenda. “They said: with this over-modulation our planes may crash! It was that level of a discussion… Airplanes have never crashed because of radio in neither New York nor Paris, which are the two loudest cities in the world.” This led to the introduction of MPX Power in several countries, where broadcasters now have to limit the average modulation: “You can afford to have some peaks, but not to be loud all the time, as you would then go over the power limit. So, there’s no point in clipping the audio anymore.”
But there is one catch: “Modulation power is being measured at the composite signal, meaning after stereo coding and after pre-emphasis. Unfortunately it doesn’t match sound processing to how we humans hear audio at all. Bass is using up a lot of power, and so does treble, due to pre-emphasis. Some stations have tried to be louder, even with MPX Power regulation, by cutting out their bass and treble.”
Find bass & energy balance
That’s sounds horrible! Predominantly mid, that’s close to a phone line…
“Exactly. The Omnia.9 has ways to manage this, like a feature that makes the bass punchier without using up too much energy. It’s kind of a simple trick: a matter of adjusting the side-chain delay on a compressor that only handles bass. It allows you to have a nice, punchy, natural sound at a reasonable volume, even with MPX Power limitations.” The company is now building a complementary device that could boost its flagship processor’s market share in Europe; a separate stereo generator. “Omnia.9 has its own stereo generator, but it’s inside the unit and you probably want that at the station; not at the transmitter site.” The Omnia.9 SG will be released at the NAB 2014. “It will also include the psychoacoustic distortion-masking composite clipper, which is part of the key to a clean and loud sound.”
“Loudness is only important
during the first 2 seconds”
Avoid adding (much) pre-processing
Do you have 3 takeaways for radio professionals who are looking for a great on-air sound?
1. “Do not compress, limit or equalize audio before it gets into the sound processor, so the Undo function of the Omnia.9 has a chance to do its job. There are many tools in the unit to create your signature sound, such as equalization and compression. If you add pre-processing, the de-clipper can’t function and you’re still left with distortion. Keep the audio signal that goes into the unit as clean as possible. Don’t worry about the signal sometimes being quiet. The audio input has 24-bits of resolution, meaning: the noise floor is at -144 dB. So even an extremely quiet signal can be brought up with no audible noise penalty.”
2. “Loudness is only important during the first 2 seconds. The first thing people do after they find a station that they want to listen to, is adjusting the volume”, Claesson knows. “Don’t kill your sound over that last dB of loudness. It’s not worth it. People will get tired of listening to the radio, without even knowing why. They’ll turn it off and listen to their iPod instead.” (A comfortable sound can help you to increase your Time Spent Listening.)
Use top-quality sound files
3. “Hard drives are cheap. Don’t use MP3; use WAV or FLAC files. I don’t know if FLAC is supported by most radio automation systems, but it’s a lossless compression – like putting your audio files through a ZIP, except that it’s optimized for audio. It’s bit for bit accurate and a nice archive format. Otherwise, use WAV.”
“There’s nothing more differentiating for me as
to have someone turn it up past the breaking point”
Ignore loudness war temptations
You’ve heard many stations in many markets. Which ones have a really good sound, in your opinion – whether they have an Omnia or not?
“Radio ABC in Denmark does have an Omnia.9 and they’ve set up everything correctly, so if you listen to their stream online I think you’ll like the sound. Then there’s COOLcelsius 91.5° in Bangkok who also have a very good-sounding 64 kB AAC+ stream.”
That’s the most original station name I’ve come across in a long time!
“Yes! They also have a second channel, COOLfahrenheit 93°, with Thai Pop. COOLfahrenheit still uses an Omnia.6, but COOLcelsius has an Omnia.9. They also have a well-programmed station; definitely one of my favorites – and I’m always listening online”, says Claesson. He resides in Thailand, but has airports as a second home as he travels to clients a lot.
Have a listener-friendly sound
“There’s nothing more differentiating for me as an audio engineer than to have made a unit which allows you to be clean and loud, and then to have someone turn it up past the breaking point anyway. So I can’t recommend any of those, but I can recommend Radio ABC and COOLcelsius. They do a good job.”