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Old 23rd July 2011, 07:02 AM   #14231
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by jneutron View Post
Pics attached..edit..sorry about the pdf, I gotta change that to a jpg..

I believe most of this is self explanatory.
Most of this requires no more that EE101 or even the electrics in high school physics to understand.

But because it is not explicitly taught in most EE courses it seems it is by far too frequently ignored.

I am just wading through a week worth of dither in this thread (which I can assure everyone has neither improved resolution, nor increased the amount of usable information in the thread and certainly not the SNR) after soaking up see air, sunshine and way too Margarita's and Mojito's and what I am most shocked by is just how many really basic EE knowledge is shown to be absent.

Several decades I worked in industrial process control electronics, where the "stake" if something was wrong was 140 tons of liquid steel (which in the worst screw-up would destroy thoroughly the machinery and the lesser ones just meant the loss of a LOT of money).

Things like the errors introduced from metal/metal contacts and all sorts of noise sources where understood, accounted for and hence caused no issues (unless some ejit in maintenance ignored the instructions on how to make contacts etc. and hence nothing worked as expected - that ejit usually never got the the chance to do it again either).

Meanwhile in audio the same issues are simply attempted to be "talked away" by some while others, who try to draw attention to such issues are laughed at and all this is called "bunkum" while obvious bunkum is talked up to the level of factual science...

If I was not such a hardened cynic I would probably despair, but as it is, while I delight in the occasional flashed of sense and attempts to general betterment, I am never surprised by the opposite, so it's basically just back to "business as usual".

Well, the sun and sea was nice while it lasted... Maybe I should give up and go back to the seaside and just be known as "Son Of the Beach"...

Ciao T
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Old 23rd July 2011, 07:13 AM   #14232
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by PMA View Post
Dither is a popular issue here...
Not only here.

I remember that I when I once pointed out that the theoretical Dynamic Range derived by the milkmaid calculation of the number of bits is not accurate as it is not possible to encode such a signal in a digital system (e.g. -96dBFS peak level for 16 Bit's) dither came up again and again, however showing such a signal showed a noisefloor that was increased sufficiently to degrade the real SNR and only massive averaging could reveal the low level signal...

Yes, dither can reduce the appearance of distortion of quantisation distortion (again, this is apparency, not an actuality), but at a price.

One MAY consider in some specific conditions used dither, to overcome problems with measurability or sensor thresholds in specific applications, however to simply derive from such limited and specialised applications that dither has universal and general benefits and improves resolution everywhere is absurd...

Ciao T
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Old 23rd July 2011, 07:18 AM   #14233
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by jneutron View Post
Yes. It also fails code to do this.
There are of course many ways in which one may deal with ground/earth loops, secondary path issues and other "equipment ghosts" (which have not a small impact in all this cable differences and related controversies IMNSHO) without failing the electrical safety code, it just costs a little more and needs recognition and understanding of the issues, "talking it away" is cheaper and easier.

Ciao T
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Old 23rd July 2011, 07:26 AM   #14234
Previously: Kuei Yang Wang
 
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Hi Simon,

Quote:
Originally Posted by simon7000 View Post
Nice plot. Try it with a signal of 15 mv and still look at -150 into a high impedance load. I think at those levels something shows up.
I would suggest that a high impedance load is the opposite of what you would want to show anything like "micro diodes", or similar effects that are essentially rectification related.

One needs to construct a test that is appropriate to show (maximise the visibility?) of the effect we theorise about.

I would suggest that high source impedance and appreciable loading would more likely demonstrate problems in at least this domain.

You even hinted at the core of this, when you quipped that you never saw anyone ping a condensor mike to overcome bad contacts at the capsule... There are reasons for that.

Ciao T
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Old 23rd July 2011, 08:18 AM   #14235
jkeny is offline jkeny  Ireland
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Here's something that I read recently from John Swenson which may be of interest when it comes to consideration of "Threshold of audibility" - I quote it in full
Quote:
On the "threshold of audibility" issue I think its enlightning to look at another field. Photographic film takes a certain brightness to cause any change at all in the film when developed, BUT a much smaller change in brightness will make a change in density when the average level is higher. For example an exposure change from middle gray to something very slightly brighter can make a change in the negative even though the change in brightness was significantly less than the "minimum threshold".

Given that we know that the human hearing transfer function is not a perfectly straight line starting at exactly zero, I would not use the "threshold of audibility" to make predictions about anything, especially things that are far from zero.
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Old 23rd July 2011, 09:56 AM   #14236
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Hi ThorstenL Re; your post #14,229.
The first line where you express doubt (or stronger sentiments) about noise increasing resolution.

I can't put my hand on it now but in what used to be "Wireless World" (can't think of current name.....Electronics World..is it?) there was a short piece 3-4 years ago that claimed precisely that. Now it wasn't at audio frequencies but the reason it caught my attention was that a number of us have found that vocals heard while driving a car often appear easier to understand than in the lounge room and I was just wondering if the extra low frequency noise in the car had something to do with the increased clarity.


Jonathan
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Old 23rd July 2011, 10:04 AM   #14237
SY is offline SY  United States
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Quote:
Originally Posted by ThorstenL View Post
Hi Sy,
Ahhh, this is interesting. So if I add more noise to my Phonostage it will increase resolution?
Do you have a digital phonostage which plays digitally encoded records? Or does your phonostage have terrible quality components in it with multiple dead bands? If so, then possibly yes. If not, then perhaps reading things in context might be useful.
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Old 23rd July 2011, 10:25 AM   #14238
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by Jonathan Bright View Post
I can't put my hand on it now but in what used to be "Wireless World" (can't think of current name.....Electronics World..is it?) there was a short piece 3-4 years ago that claimed precisely that. Now it wasn't at audio frequencies but the reason it caught my attention was that a number of us have found that vocals heard while driving a car often appear easier to understand than in the lounge room and I was just wondering if the extra low frequency noise in the car had something to do with the increased clarity.
I find this interesting. It would be good if you could find the reference.

My native language is German and especially in my earlier years in the UK I had many problems understanding the lyrics of English songs. Noise never helped. Indeed, I think much of my work in HiFi at the time was spurred by this. It took much work to get to a point where I could listen to CD's/LP's and just understand.

My improving english no doubt helped, but I could easily follow a conversation in a noisy pub between a bunch of people speaking english with irish, jah-meican and sundary other accents but even there less noise helped intelligibility while I still had problems following english lyrics past the basic pop song level when hearing them on crappy sound systems, but non on ones I consider "good". In fact, even now I find english lyrics on "consumer grade" gear at times difficult (say stuff like Marillion, some songs by Kate Bush or Enya etc.).

For want of better word, hifi gear that I dislike has a "noisy" sound, it seems to have a subtle signal dependent noise behind the music (I know some call this "detail", to my ears it is not, I never hear this from a live acoustic instrument), I would not call it distortion as such, that makes it more difficult and more of an effort to follow phrasing, lyrics/vocals and the like...

The real fun part is, music with german lyrics, even stuff hard to understand for many germans I can follow easily on almost any gear, I still would not claim that noise helps... Still, such music I also enjoy more with the kind of HiFi systems I favour.

Ciao T
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Old 23rd July 2011, 10:30 AM   #14239
Previously: Kuei Yang Wang
 
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Sy,

Quote:
Originally Posted by SY View Post
Do you have a digital phonostage which plays digitally encoded records? Or does your phonostage have terrible quality components in it with multiple dead bands? If so, then possibly yes. If not, then perhaps reading things in context might be useful.
So, you claim ADDING NOISE to a digital system reduces noise and improves SNR/DNR? And doing the same to an analogue system does the opposite?

Or do you claim that the LOSS of SNR/DNR and thus resolution and ENOB when applying dither has magic properties that places it outside the realm of normal physics?

Or do you claim that there is some hidden digital distortion (not covered by traditional measurements) that dither mitigates, so the loss of SNR is preferable to leaving the hidden distortion?

Or what precisely is your claim? You are not very precise.

Also, do you have some serious references or measurements that show how dither improves RESOLUTION (which I would suggest is best evidenced as Effective Number Of Bits [ENOB])? Or maybe a DBT that demonstrates that dither improves "resolution"?

Ciao T
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Old 23rd July 2011, 10:33 AM   #14240
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When you find me saying that dither increases SNR as you falsely attribute to me, I'll apologize for calling you a liar yet again.

If you think quantization distortion is "hidden distortion" then you truly have no understanding whatever of digital systems. I don't believe that's true, so I'll assume you just want to argue for argument's sake, which does not interest me.
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