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Old 8th January 2013, 09:14 PM   #8001
dvv is online now dvv  Serbia
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My point is that once you manage to install a preconception in the public eye, it will take ages and tons of luck and money to change that.

Look no further than THD specs - the public at large still believes the smaller the number, the better the sound. Why? Well, quite simply, they have been drilled into believing that by the entire industry, which has worked hard for the last 50 years or so to make it happen.

This is the same. Some copywriter in some ad agency was erroniously told that these are digital devices, and even reputable magazines, such as for example Hi Fi News & Record Review, also went on to tell us that for example TaCT Millenium was a 100% digital amplifier.

The manufacturers sure were happy to promote that image. The public at large doesn't know analog technology, so digital is to them a mysterious domain where much unholy was going on. Nobody dares to ask. They just cough up the dough.

Ultimately, it's all about the money.
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Old 8th January 2013, 10:11 PM   #8002
DF96 is offline DF96  England
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Quote:
Originally Posted by dvv
Seriously, DF96? How? Why?
I believe it was an EU decision. Early tests by the BBC were all at 256kb/s, where MP2 works quite well. At the 128kb/s bit rates now used for most stations MP3 would work better. DAB+ with AAC coding would be an improvement, but it would render obsolete most current DAB receivers so few politicians have the guts to propose it. Eventually they will have to choose between three unpalatable options:
1. ditch DAB and stay with analogue
2. ditch DAB and upgrade to DAB+
3. ditch analogue and force people to use DAB
Their favoured option of a rapid voluntary migration from analogue to DAB is just not happening, because of reliability and sound quality issues. The longer they leave the decision the harder it gets.
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Old 9th January 2013, 01:34 AM   #8003
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Quote:
Originally Posted by dvv View Post
also went on to tell us that for example TaCT Millenium was a 100% digital amplifier
I think I remember about it being some kind of all-digital contraption, so I googled...
looks like it was. based on the soundstage.com blurb, it seems that it's a PCM to PWM converter, which is digital. problem is that it's impossible to make it decent (at least from an objective stand-point) without post-filter NFB. because of load influence, switchers dead-times and rise-times etc. damn, we tried to keep it all pure (read digital) and 2 damned transistors, one coil and a cap ruined all that pureness.
so how do you solve that? you add an ADC which is, well, an analog-to-digital converter. so it's not digital after all. obviously a case of marketing combined with dogma. maybe the designers themselves truly believed that it will be viewed as the long awaited perfect amp, because it maintains the "digital pureness" up to the output stage.
but most currently available implementations have analog inputs, the modulators are analog, there is no DSP, ADC or DAC involved. so it's all analog.
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Old 9th January 2013, 03:00 AM   #8004
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The BBC were always early adopters. DAB+ is what developed when others waited and studied what happened.
Digital TV picture CAN be better than analogue, but only with adequate bit rate. Too low to squeeze in more channels and you end up with horrible artifacts on movement.
Analogue radio and TV had the huge advantage that there was little motive for the bean counters to cut quality as they had fixed channel bandwidth
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Old 9th January 2013, 06:34 AM   #8005
dvv is online now dvv  Serbia
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Quote:
Originally Posted by mr_push_pull View Post
I think I remember about it being some kind of all-digital contraption, so I googled...
looks like it was. based on the soundstage.com blurb, it seems that it's a PCM to PWM converter, which is digital. problem is that it's impossible to make it decent (at least from an objective stand-point) without post-filter NFB. because of load influence, switchers dead-times and rise-times etc. damn, we tried to keep it all pure (read digital) and 2 damned transistors, one coil and a cap ruined all that pureness.
so how do you solve that? you add an ADC which is, well, an analog-to-digital converter. so it's not digital after all. obviously a case of marketing combined with dogma. maybe the designers themselves truly believed that it will be viewed as the long awaited perfect amp, because it maintains the "digital pureness" up to the output stage.
but most currently available implementations have analog inputs, the modulators are analog, there is no DSP, ADC or DAC involved. so it's all analog.
Gotcha.
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Old 9th January 2013, 06:38 AM   #8006
dvv is online now dvv  Serbia
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Quote:
Originally Posted by davidsrsb View Post
The BBC were always early adopters. DAB+ is what developed when others waited and studied what happened.
Digital TV picture CAN be better than analogue, but only with adequate bit rate. Too low to squeeze in more channels and you end up with horrible artifacts on movement.
Analogue radio and TV had the huge advantage that there was little motive for the bean counters to cut quality as they had fixed channel bandwidth
No artefacts here, thank you. Well, on a bad day, some marginal channels do have some artefacts, but not the big gun channels, like Fox, Universal, BBC, etc.

And, thankfully, not my favorite channels, like National Geographic, History channel, Viasta History and Animal Planet. NatGeo especially has a very high quality picture, thank god Electron.
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Old 9th January 2013, 09:40 AM   #8007
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Somebody said to me once that digital is the same as analogue with twice the problems . It is very simplistic and has a grain of truth in it . We should at 44.1 kHz dismiss the bandwidth issue . If a one bit system it is a bit more relevant . The guy said and I never check for myself this . If you put a low grade analogue buffer on the analogue or digital side the degrading effects are simlar . The buffer would have the bandwidth it should be stressed . A low grade video amp might work well as a test . He was quick to say many never question the need for anything special in the digital domain . My instinct is to say the digital is not as important . However with a little thought maybe it is ? Similar sonic traits which may not come from exactly the same origin .

So in a nutshell extending the though a little ( I hate calling it a digital amp , if so it would do direct digital decoding without too many steps ) . All that is wrong with class D is it adds a layer of complexity ( some layers ) . However poor the amplifiers I make they are my own designs . Some so weird I would never show them ( daft designs which I had to try , some are very good , most are even by $2 radio standards minimalist ) . One thing I do find theses days is mostly what I design works first time . I can mostly do that without any special precautions . That says to me they are inherently stable . I dream of the day I master class D the same . As I said the other day we can all become consumers . If a Ferrari I see virtue in that . A postage stamp amplifier with quirky working ? No , you buy it .

A question which I know the answer to but would like others to say . A friend has written to me about obsolete Japanese transistors . RS still list 2SA1085 which is well beyond superb ( PNP , 90 MHz , 0.55nV / root Hz , 120V , hfe 300 , Cob I guess 2 pF ) . I notice if my eyes don't deceive me that BC640 would be pin compatible ( 2N5401 not ) . Looking at it's spec it looks almost OK . Did anyone ever use them as inputs ( Velleman /Elector did ) ? I notice MPSA 92( 42 ) gets used sometimes . Is it too much of a leap to say BC640 is generic ? Being a mini power transistor ( like BD140 I have always guessed ) it might have low noise . 2SA970 if fine ( 2SA872A ) .
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Old 9th January 2013, 10:58 AM   #8008
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Quote:
Originally Posted by DF96 View Post
I believe it was an EU decision. Early tests by the BBC were all at 256kb/s, where MP2 works quite well. At the 128kb/s bit rates now used for most stations MP3 would work better. DAB+ with AAC coding would be an improvement, but it would render obsolete most current DAB receivers so few politicians have the guts to propose it. Eventually they will have to choose between three unpalatable options:
1. ditch DAB and stay with analogue
2. ditch DAB and upgrade to DAB+
3. ditch analogue and force people to use DAB
Their favoured option of a rapid voluntary migration from analogue to DAB is just not happening, because of reliability and sound quality issues. The longer they leave the decision the harder it gets.

I have been thinking for sometime now to ask the BBC if they could let us have what would call their up links to their FM transmitters . It might still be 13 Bit Nicam ? I will probably find it has been MP2 or whatever for years and my prejudices have preferred FM . If so it is ringing in the MPX filters I love or whatever ? I don't think so ? I am told the pumping effects come in at - 78 dB , without hiss we might hear that ? I think I could live with that . The listening panel at the BBC in 1972 said they could in both respects . They were after a reality to the sound within what was possible then . Harness I was told often was the result of technical solutions that looked good on paper . Measured problems of seemingly greater importance were often more acceptable to the listening team ( these would include technically gifted engineers with a musical background ) . The way the Near Instantaneous worked ( NIcam ) was important .

The idea would be to stream it over the internet . I have no great knowledge if that would be easy .
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Old 9th January 2013, 11:41 AM   #8009
DF96 is offline DF96  England
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I believe BBC program distribution still uses NICAM, but I don't know which version. It might be the 13-bit non-linear system - that seems to work very well. Nasty sound on FM mainly comes from incompetent studio engineers, poorly trained journalists (who now have to make their own recordings!), and the audio compression applied at the transmitter to make the signal loud (some for the BBC, lots for commercial stations).
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Old 9th January 2013, 01:03 PM   #8010
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I was at a Radio 3 recording just before Christmas . It all looked very serious and very correct . It will be interesting to compare memory against the broadcast ( Britten Psalms , Poulenc Gloria ) .
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