I haven't heard DAB through a HiFi setup, what were the circumstances under which you heard it?
I've heard a couple of decent hi-fi setups with DAB tuners and external antennae.
BBC Radio 3 FM seems to be the 'gold standard' in terms of bandwidth, I don't know if Radio 3 DAB is given a comparable bit rate?
Well, an FM Stereo station is fixed as far as transmission bandwidth goes. There is only one transmission standard which uses just over 100KHz of bandwidth for a Stereo signal, IIRC (ignoring any other subcarriers such as RDS, etc.). Distribution to the transmission site is another issue, though.
DAB does give the flexibility to assign a variable bit rate (and hence share of the bandwidth) depending on the channel content - not much point in using a lot of bandwidth for a speech-only channel like 5 sports extra!
The problem is, it's reckoned that with the ancient MPEG 1 Layer 2 coding used by DAB in the UK you need 225 KBits/sec bit rate to equal FM quality, and that takes more than twice the bandwidth of an FM station to transmit digitally - so, as it stands, DAB is less efficient in the first place. Then consider that even the main BBC channels are only transmitting at 128-192 Kbits and this is where the quality suffers.
With any digital to analogue conversion the black magic seems to be filtering out the digital artifacts. I would hope that the manufacturer of a HiFi DAB tuner would get that right.
The D to A conversion is actually pretty easy, especially with modern DACs that need very little filtering after them due to the digital filtering built in. It's the compression algorithm where you throw away large chunks of detail from the signal to cut the bandwidth. Compare DAB, MP3, MiniDisk, etc. (All marketed as "CD quality" at some point
) with a format like CD, where there is no compression and the difference is like night and day IMHO.
The Blaupunkt I have been using seems excellent to me on both FM & DAB but I might not be so impressed if I were listening to it through reference speakers in a sound studio.
This is it. For casual listening it's probably acceptable. It's just the opportunity for serious listening, which, IMHO, exists with FM alongside causal "sit in the corner and make a noise" use, is denied by DAB.
It's also a shame that DAB+ is being shunned in the UK because that could have gone some way to redressing the issues by including better audio codecs and error correction. In the rush to push DAB a lot of radios that don't support DAB+ have been sold so this is now a non-starter.
I'm afraid I will be sticking with my "£15 from a junk sale" FM tuner 'til the bitter end. Even then, I have the same radio stations available over DVB and satellite TV at a higher or comparable bit rate to DAB. I can also listen to internet radio stations if I really feel the need to listen to low bit-rate digital audio.
Given that I'd need to put up another antenna for DAB (I agree that a decent antenna is a must for DAB or FM alike) I can't see myself bothering.
I have a small Sony DAB in the bathroom...
Sssh! "You know who" might be listening!
The first is that the better the aerial location with regards to the outside elements, the better the reception is going to be.
Agreed. this is true with anything, FM, DAB, etc.. It's just with DAB the sound quality is capped at a lower level by the compression algorithm.
And the second is that there are some wild differences with build quality and this also has a major effect.
Well, I'm sure there are good receivers and bad. Once they have the S/N margin that they need to receive a digital signal error-free that shouldn't really come into play in terms of sound quality, although in a car environment it also has to cope with interference and multipath, of course.
Kevin
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Topic: DAB Radio (Read 4085 times)