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Old 4th November 2011, 06:49 AM   #17521
1audio is offline 1audio  United States
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Quote:
Originally Posted by dimitri View Post
Looks like a digital version of the 3M Dynatrac. Not much new but sorting out the bits isn't easy.

This has 24 bit accuracy: LTC2442 - 24-Bit High Speed 4-Channel Delta Sigma ADC with Integrated Amplifier - Linear Technology but it samples at 8 KHz. And this is a real 24 bit DAC: http://us.flukecal.com/products/electrical-calibration/electrical-standards/720a-kelvin-varley-divide But the sample rate is specified in minutes. It IS all discrete.
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Last edited by 1audio; 4th November 2011 at 06:57 AM.
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Old 4th November 2011, 07:59 AM   #17522
rsdio is offline rsdio  United States
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The crux of the dither argument seems to be semantic. What one person calls "fuzzy distortion" is what I would call noise. To be certain, what you put into a digital system is not what you get out, and therefore it is "distorted." However, what you put into an analog system is not what you get out, and thus analog systems are also distorted. In general, the digital systems get much closer to the truth, especially when discussing recording systems and/or systems that go through a large number of generations of reproducing the same signal.

I don't see the point of complaining about the "fuzzy distortion." If we could literally see the pattern of magnetized molecules on a tape, I'm sure it would look just as ugly as the computer displays of digital samples. Even if there were some subtle beauty to the patterns, the bottom line is that the signal coming out of a tape recording is much "fuzzier" than the signal that went in, and thus there is a undeniable amount of distortion.

I think some folks are deluding themselves by assigning loaded terms to the inaccuracies of one system versus friendlier terms for the inaccuracies of another system. Everything has noise, everything is distorted. It's just a matter of degree.

Keep in mind that the pictures you see on your computer monitor are not the waveforms that your amplifier is sending to your speakers. Digital audio always passes through some amount of non-ideal analog circuitry before you can hear it, and this non-ideal analog circuitry does not recreate the ugly waveforms you see on your screen. In a properly designed DAC, the waveforms coming out are much nicer. I'd prefer to see photos from an analog scope connected to a proper DAC, then we'd have a realistic image of any "fuzzy distortion" (or noise).
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Old 4th November 2011, 08:35 AM   #17523
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Quote:
Originally Posted by abraxalito View Post
Those guys don't have anything near a 24bit converter - they claim 124dB in 25.6kHz bandwidth. They get better only by going to a narrower bandwidth, looking like they use synchronous averaging. Been there, done that, back in the 1980s.

EXACTLY!


Most of the people who discuss digital audio do not understand that at any technological state, the product between speed and accuracy is constant. In our case there is a tradeoff between sample rate and how many bits can accurately represent the signal.

We can have 24 real bits if the bandwidth is 10Hz, for audio bandwidth we can achieve 21bits and if we have gigahertz we have a maximum of 4-5bits.
So even if we not take in consideration other limitations, bandwidth is one of the factors that influence accuracy.


In this context all the discussions about how to increase sample rate to 192Khz, 384KHz or even 768KHz looks absurd. You trade accuracy for speed, speed that will not give you anything. 96KHz is plenty enough to include all the info in the audio bandwidth.


chrissugar
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Old 4th November 2011, 08:48 AM   #17524
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by chrissugar View Post
Most of the people who discuss digital audio do not understand that at any technological state, the product between speed and accuracy is constant.
This is quite obviously untrue.

Using classic PCM tech there is no such link.

With a given pure multibit DAC or ADC I will get the same accuracy fundamentally at any given sample rate the converters logic can handle.

E.g with a PCM1704 I can operate at 44.1KHz sample rate with 22.05KHz bandwidth or at 768KHz with 384KHz bandwidth.

While the incrase of bandwidth will increase johnson noise, you will clearly find that the product between bandwidth and accuracy will rise significantly every time we bump up the sample rate and is NOT constant.

QED.

Of course, within the given system I COULD trade off bandwidth for more apparent resolution at lower frequencies, I believe abraxalito covered this a bit back and this is a given...

In our example case it is unlikely to help as the available analogue SNR is too low, though with 16 * Oversampling at 48KHz we could theoretically add four more bits to the existing 24...

Ciao T
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Old 4th November 2011, 08:50 AM   #17525
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Quote:
Originally Posted by ThorstenL View Post
Pavel,



Merci beucoup, Thank you, Danke Schoen, Děkuji, Spasiba, Mille Gracie, Domo arigato!



Now what is all this "fuzz" we are seeing?

I know what the defenders of the orthodox faith will say, it is NOT Fuzzy Distortion (as such does not exist).
Oh my god! That is the fuzzy distortion you are talking about? The noise that decorelate the wordlength reduced signal from the steps? You really do not clearly understand digital audio.
You should measure and listen after the reconstruction filter, but I can only think that you use some non oversampling no filtering DAC, so that would explain your conclusions.

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Old 4th November 2011, 09:01 AM   #17526
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Quote:
Originally Posted by ThorstenL View Post
Hi,



Which mastering converter?



Nope, it does not, hence I suggested a few methods of observing said distortion.



If so, please illustrate where I fail to understand. But please make sure you are really certain about it. Do note come quoting folksy tales of magic dither or anything of the like, make sure you really are sure that what you point to is REAL.

The sticking point is that I have choosen to identify as distortion what in fact is A FORM of distortion, contrary to the folksy "magic" explanation that it somehow actually lowers distortion, when in fact it observably increases it, for two out of three samples, even though said "folksy magic" explanation is currently favoured in audio (well, they once favoured weapons salve too).

I do not think we per se disagree about the actual technical facts, where we part company is how we interpret things. I am not the least interrested in 64K samples averaged showing a low noise floor, as this low noisefloor is an illusion, what I am interested in is the fact that two in three or many more individual samples will simply be wrong, or distorted.

So to speak, from where you stand, I fail see the wood for the trees and from I stand, you fail to see the individual trees for the wood. I personally appreciate that things are never as black/white, however it often is necessary to go black/white to get the point across.

I note that still most people here cannot see the trees for the woods, pitty that, cause the devil is always in the detail, in the individual trees so to speak and no hand waving or building straw men will change that.

Ciao T
You know what?
At this point I stop to answer to any of your post because it is useless. I will take Scott Wurcer's advice "if any amount of evidence will not change someones mind, just walk away".
You constructed your virtual world about how digital audio works and it would not matter if even God would tell you how things work it would not change your mind.
So for me it is waste of time, I have more important things to do. But interesting is on your part that you give credibility to flawed tests like Ethan's ones but decades of theoretical and practical experience from some of the guys who really understand digital audio (Keith Johnson, Dan Lavry, Paul Frindle and many others) do not matter. It is sad.


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Old 4th November 2011, 09:33 AM   #17527
zinsula is offline zinsula  Switzerland
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Until now, no one did convince me that Thorsten's arguments about signal handling of music (i.e. not highly averaged sinus test signals) is wrong.
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Old 4th November 2011, 10:05 AM   #17528
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Hi,

Quote:
Originally Posted by rsdio View Post
The crux of the dither argument seems to be semantic. What one person calls "fuzzy distortion" is what I would call noise.
Yet classic analogue noise and digitally created "dither noise" are usually never the same.

Tape noise is heavily noise shaped with a strong roll off starting at 50Hz, for example. Just as saying "distortion" in itself is meaningless, so is saying "noise".

Different distortions and different noises have dramatically differing audibility.

Unless and until we can agree that and then proceed to analyse the detail we remain at a point where many here cannot see the trees for the woods and hence mistake the larch for a firs, firs for redwoods, birches for oak and so on...

http://www.youtube.com/watch?v=5zey8567bcg

I agree that when you say "noise" and I say "fuzzy distortion" we are talking about the same process, but we have differing views as to what it constitutes and how it effects things, which as I pointed from the beginning of the debate was the crux of the matter.

As someone from a primarily analogue background I cannot, but see this as unnecessary added distortion and I for one do not see why suddenly something "BAD" becomes "GOOD" because someone claims "digital is different" without the slightest shred of proof.

Now many want to believe very much that what I consider "BAD" and which from an absolute view (e.g. information theory) is and remains bad, as something "GOOD".

They have faith that it is "GOOD".

They even have "miracles" (64K FFT, Averaging - miracles of the "now you see it, now you don't" kind) to underscore their faith in the goodness of it all.

Meanwhile I stand there and say "But the emperor has no clothes!". Well, I am after all only a little boy...

So, show me the clothes of the emperor and I shall recant...

Ciao T

Last edited by ThorstenL; 4th November 2011 at 10:10 AM.
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Old 4th November 2011, 10:12 AM   #17529
rsdio is offline rsdio  United States
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Quote:
Originally Posted by chrissugar View Post
Most of the people who discuss digital audio do not understand that at any technological state, the product between speed and accuracy is constant. In our case there is a tradeoff between sample rate and how many bits can accurately represent the signal.

We can have 24 real bits if the bandwidth is 10Hz, for audio bandwidth we can achieve 21bits and if we have gigahertz we have a maximum of 4-5bits.
So even if we not take in consideration other limitations, bandwidth is one of the factors that influence accuracy.
I agree with what you're saying, Chris, but I think that it's important to realize that this tradeoff comes into play only when you're at the upper reaches of what we can achieve. Thorsten tries to say that the old converters did not experience any kind of tradeoff like this, but that's because they are not operating against similar limits. If you're willing to throw out potential accuracy, then you aren't forced into a tradeoff situation. It's only when you're up against the limit that increasing the sample rate forces a reduction in bits, or vice versa.

As for the PCM1704, it's not rated above 96 kHz. It may run internally at 768 kHz, but we do not have access to that data. At least the data sheet doesn't speak to anything beyond 96 kHz. I don't see how it can be claimed that this chip is not trading off various factors internally.
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Old 4th November 2011, 10:12 AM   #17530
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Quote:
Originally Posted by chrissugar View Post
http://www.users.qwest.net/~volt42/cadenzarecording/DitherExplained.pdf

The second is written by Dan Lavry, the guy who has a deep understanding of AD/DA and digital in general:
http://www.lavryengineering.com/white_papers/dnf.pdf
http://www.lavryengineering.com/white_papers/dither.pdf

chrissugar
Nice links, thanks for posting them !
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