DAB digital radio: the crystal clear truth

by Carl Beckwith

DAB digital radio was, right from the start, a total falsehood. Marketed as a newly created platform for superior sound quality over the existing and long established VHF/FM broadcasting service for national (BBC) and local radio coverage, it was conceived using an ill-advised and ancient mpeg2 codec that meant the quality could not be high enough without recourse to using large bandwidth space.

When first launched, the BBC put the main radio stations (as per the FM service) onto the DAB platform at a bit-rate bandwidth of 192kbp/s mpeg2, (a lower level of sound quality than mpeg3 at this figure); admittedly with audio performance that would satisfy all but the most fastidious listeners who were likely to be using quality hi-fi equipment to listen to music or speech.

By ‘hi-fi’, this means very high quality engineered apparatus delivering a fidelity of sound beyond anything sold on the high-street today. Equipment that can only be found through specialist hi-fi dealers. This can include equipment made over 50-years ago using valves instead of transistors, including quality vinyl playback, (and hence the successful revival of the format against the backdrop of compressed media).

The marketing of the DAB ‘digital’ service has been nothing short of a false promise driven by an agenda backed with misinformation. The marketing drive presiding over it’s own dismal failure to inspire wholesale acceptance of the switch-over. Here’s why:

1. The initial DAB service offered with a sound at best, 192kbp/s mpeg2, was only a near match for FM.

2. FM has been spoiled by the networks applying ‘dynamic audio range compression’; not an artefact of FM, but an unwarranted ‘meddling’ of the FM platform, with the excuse that it is done for listeners in cars, – avoiding ‘quiet’ and ‘loud’ passages from causing motorists to keep having to adjust their car radio volume all the time. On a home hi-fi, this compression of dynamics spoils the dramatic listening experience. At one stage, this compression applied to FM broadcasts was used as a marketing advantage for DAB, which was not the case at all and was totally misleading.

3. Not long after DAB digital radio was launched, without telling anyone and hoping they would get away with it, the BBC lowered the ‘bit-rate’ of services: Radio 2 was lowered to a paltry ‘mid-fi’ quality of only 128kbp/s, Radio 3 to 160kbp/s and Radio 4 to as low as 86kbp/s, and mono sound, (which now sounds worse than MW/LW transmissions with peculiar side-effects persisting).

When leading technical journalist, Barry Fox, writing an article for Hi-fi News & Record Review asked the BBC about the effects of the low bit-rates applied on Radio 4, the answer was that it was only applied to speech programmes. Any Radio 4 listener asked what the appeal of radio broadcasting was, would invariably respond with it’s content of speech, including drama and discussion. Using a late 1950’s Grundig 3D Sound hi-fi table radio tuned-in to Radio 4 on the VHF/FM service, the sound of a voice appears as if right in the room. Nothing from DAB has this fidelity of sound on this most ardently revered of networks.

4. DAB radios are not as eco-green as FM radios on battery consumption; many using inefficient circuits.

5. Not many car manufacturers are backing this ‘fringe’ technology just for the UK market, when the world is content with FM.

6. The expectation of all households to simply ‘ditch’ all FM radios and have new car radio equipment installed is not only a ridiculous proposition, but brings forth the less than ecologically green prospect of landfill excess.

7. The REAL reason behind this constantly delayed ‘switch-off’, (and for many reasons, several times aborted through very intelligent arguments from well advised coverage in the broadsheets over the last ten or so years), is for the Government of the day to rake-in fortunes by selling-off the analogue frequencies (currently occupied by FM radio broadcasting) to mobile communications operators.

In short, the oft-quoted ‘crystal clear’ sound is not. The word DIGITAL is bandied about like some ‘King’s New Clothes’ ethos, because ultimately, what we hear is an analogue waveform from our resonating speakers or headphones. FM may be relaying a digital feed in the studio, but with the alternative DAB system using mpeg2, and the applied low bit-rates with an average-to-poor sound quality being offered, why leave FM?

It is time for ill-advised articles with the oft-quoted ‘crystal clear sound’ and ‘digital’ to be put to rest with the facts. FM, with a good aerial and good reception, is still superior in sound quality by a huge margin. Critics who talk of ‘hiss’ are clearly in poor reception areas or are ill-advised and not using correctly installed aerials. The same problems can arise with a DAB radio, but with different and more annoyingly audible side effects. Ultimately, FM broadcasting has the purer, richer, clarity of ‘hi-fi’ sound reproduction to the hugely flawed DAB digital radio system.