I KNOW it's not diy but ...

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On Sun, 28 Dec 2003 19:41:17 +0000, Andrew

I think that a lot depends on the individual, the equipment used and the content.
We have two professional sound engineering people as regular group contributors (possibly more), so in one sense, I would defer to their experience and expertise.
I've done some work in the digital video and audio transmission world, so have some appreciation of the technologies used.
One of the objectives of any form of digital audio or video recording or transmission is to squeeze as much as possible into the bandwidth or storage available while producing quality that is fit for the purpose. In order to achieve this, some fairly sophisticated compression techniques are used. This is not to be confused with the compression that AM pop radio stations use(d) so that the listener could hear the dross that they turn out even in a noisy environment or poor signal. The type of compression used in digital audio systems takes into account the behaviour of the listener's ear and brain and uses a psycho-acoustic model. Simply put, this means that information that the ear is not likely to perceive is thrown away and not transmitted. Of itself, this can save a lot of data transmission.
Here are some papers explaining the techniques.
http://www.chiariglione.org/mpeg/faq/mp1-aud/mp1-aud.htm
http://www.bbc.co.uk/rd/pubs/papers/paper_21/paper_21.html
Given enough bandwidth, the results can sound fine. The problem is that the broadcasters, for most of the channels are using lower data rates than are required to produce good audio quality with some types of content. Therein is the rub.
If you like to listen to classical music and to some types of jazz and have a keen ear, you will notice the effects of the compression at the low bit rates often being used, but perhaps not on a small portable set. For other content such as speech, the effects are less noticable or if they are noticable, less objectionable.
In a way it's a shame. DAB, in principle, should be able to offer good quality results and ultimately I suspect will do. However, like DVB-T (digital terrestrial TV), it is hampered by limitations of the current allocated radio spectrum. Even with today's limitations, there are still the benefits of freedom of interference as long as the signal is good (although one can argue that that can be achieved with FM).
However, the motivation for the broadcasters is to pack as much as they can into the available spectrum, first and foremost. For example, a satellite transponder will deliver one analogue TV channel but 6-8 digital channels. The problem is that the content does not in general improve.
.andy
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<snip>
That's interesting.

I've found an improvement in speech quality from the DAB set. Mind you, all our other equipment is old - not quite valve driven but past its best!

Thanks, andy, you've confirmed my experiences technically!

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On Mon, 29 Dec 2003 21:11:10 -0000, "Mary Fisher"

Not that it's directly relevant to you since you are without a Devil's Window, but digital video uses similar concepts to remove information that the eye doesn't notice.

Funnily enough, there are hi-fi buffs who will pay good money for valve driven equipment (new designs) because they feel that it sounds better. The same goes for good quality vinyl records. Notwithstanding the pops and background noise, they are said by some to sound less clinical than CDs.

.andy
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Andy Hall wrote:

Well. Thats right, they are. Full of dirt cracks pops, subtle distortions and intermodulation products. People like to listen not to the original reciording, but the sound of their imperfect kit.
I did a blind test with some amp designs once. The HiFi buff selected the design with the highest crossover distortion becuase to his ears it sounded like (and figures bore this out) his favorite Revox amplifier.
Notwithstanding the fact that the class A design alongside it was infinitely less 'edgy'; He missed the edginess.
HiFi buffs CAN tell the difference, they just don't necessarily know what is in fact a cleaner and more accurate sound. Or indeed prefer such.
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wrote:

wonderful it was when I was able to chuck analogue media. The absence of hiss etc makes any possible encoding deficiencies irrelevant. Even CDs made from analogue masters have me going "why is this so noisy?" I like loads of HF as well, so could never live with Dolby.
--
Niall

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I've seen and hear bubbling mud in Iceland and no, the DAB reception's nothing like that. Perhaps they haven't heard the real thing.
I have the increasing hearing problem of the 'more mature' person. That means that I can't always hear some speech, it sometimes sounds muffled. Since I listen to Radio 4 almost exclusively (we don't have a telly) I need to be able to hear speech well to have the full benefit. VHF is better than Long Wave but the quality of some voices still causes me problems.
The DAB receiver - a personal 'sports' one which I can slip under my pillow - fits the bill perfectly. It has half a dozen tone qualities, I admit to hardly being able to differentiate between them but a son says the difference is astonishing.What I do know is that I've been able to hear very well since I got it - on Christmas Day so it's not been a fair trial.
I have heard music on the receiver as well but possibly not the sort of music the FM hi-fi buffs prefer. I certainly can't bear the heavy bass noise. If I'd wanted perfect music reception, even for my beloved Bach, Britten and Beethoven, I'd have bought a Bose before now. It seems to me that some purists are very quick to damn the new and know all about the technology. Their opinions are meaningless to me. The best musical experiences are live anyway and they're never perfect.
Mary

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On Mon, 29 Dec 2003 21:07:11 -0000, "Mary Fisher"

That can be for a variety of reasons, including the individual who is speaking, how they sit relative to microphone, the type of microphone used, the accoustics of the room, etc.; and that's before it goes through the transmission system.
There is a deterioration in high frequency hearing with age, but if you can hear voices in the room OK and the radio sounds muffled, it isn't you.

A lady after my own heart. I even listen to it on the internet (or sometimes the World Service) when I'm travelling. VHF should certainly be better than long wave. The frequency range of the latter is not very good at all, then with compression to overcome the background noise, it does sound very odd.

You may find that because it is a small set, its low frequency response is probably not as great as a larger system. This will probably help you a bit because it will tend to take out some of the low end stuff that may be making speech sound muffled sometimes.

I know what you mean but would probably add Sibelius, Brahms and Vaughan--Williams to your list.

True. At the end of the day, if it does the job that people want then they will buy it.

Also true, but I have to say that I shall long remember attending concert of Sibelius and other Nordic composers at the Finlandia Hall in Helsinki a few years back. The atmosphere and the performance of Symphony No 2. by Jukka-Pekka Saraste and the Finnish Radio Symphony Orchestra was quite amazing.

.andy
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I know. It's certain voices and not always for the same reason. And I can't be bothered trying to understand them any more. Life's too short, it isn't as though they're unique words of wisdom.

And through the occasional sleepless night :-)
Mary

Well, V-W, some of the others, and Mozart and Mahler and ... oh shuttup mother!

Mary
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That's interesting - do Bose receivers really work. The folded horn design is good, but they seem to be too small for the job of first class reproduction.
After years of going after hifi, I've now given it up, as ISTM the higher the fi the more I heard deficiencies rather than music. Even in digital it's very often possible to hear the digits shuffling, and you CAN'T not notice it!
Andy's points about psychacoustics are well made; it is interesting to consider how much pleasure you can get from a manky medium wave tranny in an old banger rattling along the road.
An awful lot of your perception is memory cued by the sounds emitted, and you can and do for example add an octave of bass that the receiver simply cannot produce.
I find in my old age I get a lot more pleasure from grotty little receivers than when I had big hifis (I only recently gave away my Radford Auditoriums, the were a bit de trop for my Technics music centre - with dolby B to liven up the telly!)
mike r
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mike ring wrote:

Not really.

They are.

Mmm. Its often other things like the compression and Dolby shit put on the original recordings. Dolby is probably the worst invention ever in teh history of Hi Fi.

Indeed. Most records cut on the 50's and '60's had massive amounts of bass and upper mid boost, to make them sound acceptable on a 5" paper coned loudspeaker in a cardboard box, attached to a receiver that could barely manage 5khz bandwidth.

Frankly te best I have heard has been eithjer in studios with enormous monitors, or indeed teh tiome I was working with a loudspeaker company, and we managed to crack teh ceiling playing heavy reggae through a few kilowatts of 15" bass units and a selection of JBL chiense copey mid range horns and tweeters. Its about the only rig I have ever heard that could actually produce substantial energy in the 40-80hz region.
Best commercially available speakers IMHO are the Spendors. But its a few grand a pair these days I believe.
Folded horn and transmissin line speakers don't cut the mustard on bass guitars, but are OK for organ type bass. The pgase shift muddies up teh thumping attack on a bass guitar.
Best is a pair of floppy 15" units with ultra compliant surrounds, ultra stiff cones and very long voice coils stuck on a 1" thick baffle mounted in an old fireplace stuffed with rockwool, using the chimney as a baffle....For mid range nothing beats metal horns with serious compression drivers, tho they get big, and metal bullet tweeters (horns again). That was essentially the best high volume rig I ever heard.

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Its about the only rig I have ever heard that

Try Tannoy circa 1980
Regards Capitol
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Capitol wrote:

Yup. Sadly no longer...

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wrote:

Domestic sound will always be a compromise bass wise, unless you live in a huge house in the middle of nowhere. I own a pair of JBL clone 15" scoop bins which rock, but are in no way suitable for domestic use. When used in anger, a female member of the audience seated near the front complained that "it was like sitting on a vibrator". The person she complained to replied "We charge extra for that."
I have a set of drawings for a 2 x 15" TCB enclosure. One of these days...
--
Niall

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Or in the inner city with 24 hour BIG fireworks ...

That's the one. I imagine.
Mary
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can catch whatever of interest. It's about 3 seconds here.
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Yes, the same is true for digital radio on Freeview.
--
Alan
mailto:news2me_a snipped-for-privacy@amacleod.clara.co.uk
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On 26 Dec 2003, Mary Fisher wrote

Yes, it is. (I think it has to do with coding/decoding the digital signal.)
I understand the lag on the time pips is *really* annoying to some people. (It doesn't bother me, as I don't use the pips any more for setting clocks: the best invention in years was the invention of clocks that set themselves automatically...)
--
Cheers,
Harvey
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Only once has it been in error. One night the alarm went at 5 instead of 7, and the clock was displaying 7. It was one of those gut wrenching feelings of being woken early and then confusion as to why it was dark etc.
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Yup.
--
*Laugh alone and the world thinks you're an idiot.

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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In an earlier contribution to this discussion,

Lots of replies have explained this in terms of digital processing delays.
A similar problem exists with synchronisation between radio and TV. In the past, with analog simulcasts <sp?> you could watch programmes such as the Last Night of the Proms on TV and listen to the sound in higher quality on Radio 3.
Can't do that any more - because sound and vision are not synchronised when transmitted by two different digital media.
There's progress for you! <g>
--
Cheers,
Set Square
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