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Old 19th January 2006, 08:42 PM   #111
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Quote:
Originally posted by serengetiplains
Call it what you will, capacitors muck up AC signals in a way that seems tightly correlated with their DA rating.
Ok, but DA is also rather tightly correlated to dielectric constant as well as other parameters such as dissipation factor. So which comes first? The chicken or the egg?

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Beyond stating that correlation, who really knows how capacitors *actually* muck up AC signals?
I dunno, I think we know quite a lot about capacitors and how they affect AC signals.

But you seemed to be saying rather matter of factly that DA causes "ghosting." I was just trying to figure out exactly what you meant by it.

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Steve, your use of the word "erroneous" suggests you're one who does know. Care to share?
No, I was simply speaking of those who reach erroneous conclusions due to misunderstanding basic energy storage, conclusions which if true would mean there must be second "ghost" signals even with ideal capacitance and inductance, which of course there isn't.

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Old 19th January 2006, 09:53 PM   #112
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Quote:
Originally posted by Steve Eddy

Ok, but DA is also rather tightly correlated to dielectric constant as well as other parameters such as dissipation factor. So which comes first? The chicken or the egg?

...

But you seemed to be saying rather matter of factly that DA causes "ghosting." I was just trying to figure out exactly what you meant by it.
Chicken, egg, DA, DC, DF, doesn't really matter so long as the correlation exists which, if it exists, can be used as a guide for classifying, and even designing, capacitors on a scale of better to worse.

Re ghosting, ever see the U2 video for "Vertigo" with the outline of Bono et all streaming into the distance? I mean something like that. What goes into a capacitor does not come out all at the same time. I'm assuming all comes out eventually, either as heat or as electricity, mostly electricity.
 
Old 19th January 2006, 10:13 PM   #113
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Quote:
Originally posted by serengetiplains
Chicken, egg, DA, DC, DF, doesn't really matter so long as the correlation exists which, if it exists, can be used as a guide for classifying, and even designing, capacitors on a scale of better to worse.
Fair 'nuff.

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Re ghosting, ever see the U2 video for "Vertigo" with the outline of Bono et all streaming into the distance? I mean something like that. What goes into a capacitor does not come out all at the same time. I'm assuming all comes out eventually, either as heat or as electricity, mostly electricity.
Um, ok.

No comment.

se
 
Old 19th January 2006, 10:39 PM   #114
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Quote:
Originally posted by jam
ghost: In the transmission or recording of raster-scanned analog television signals, an artifact manifested as a weak, ghost-like secondary image, offset (in the direction of the scan) with respect to the position of the primary image. Note: Ghosting is probably most familiar as a consequence of multipath rf reception of a broadcast television signal. The slight delay in the arrival time of the reflected signal results in the display of a secondary image that follows the primary.
When ghost is present, if you amplify the signal you amplify the ghost too.
That's why it's better to have a weak, grainy signal reception, with no reflections (ghosts) which is easy to solve with an amplifier.
Btw, on the NTSC system the ghost also has colour, it blurs the contours, a complete mess.
On the PAL system the ghost is transparent.
That's one of the reasons why the PAL system is better for (terrestrial) air transmission.



Back to audio mode...
 
Old 19th January 2006, 10:51 PM   #115
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Folks, there are many imperfections in capacitors. DA is related to the material in the dielectric. Aluminum electrolytic caps tend to have the worst DA. Dissipation factor is only slightly related to DA, but is most concerned with heating of the cap, due to its losses. This includes DA, but also connection resistance and lead resistance. DF is important in switching supplies so that the filter cap does not overheat and explode.
ESR is again related, but is mostly concerned with the 'short-circuit' aspects of the cap, and how well it will pass signals without any drop across it.
These are approximations, and you all can quibble with me about them, but it is important to understand that they are not all the same thing.
DA was found to be important, first, in analog computers, popular in the 1950's. It was known to effect calculations, and was difficult to compensate for. It is also very important in sample and hold circuit operations.
Tantalum and ceramic caps can have lots of nonlinear distortion as well. Aluminum caps are better, but not perfect in this respect.
 
Old 19th January 2006, 10:58 PM   #116
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Quote:
Originally posted by john curl
DA was found to be important, first, in analog computers, popular in the 1950's. It was known to effect calculations, and was difficult to compensate for. It is also very important in sample and hold circuit operations.
Well it's obvious why DA is so important in those circuits. But we're not talking about those circuits. We're talking about analogue audio circuits.

So, what is the effect of DA on an audio signal? For starters, it's not anything like a U2 video.

se
 
Old 19th January 2006, 11:08 PM   #117
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Folks, there are many imperfections in capacitors. DA is related to the material in the dielectric. Aluminum electrolytic caps tend to have the worst DA. Dissipation factor is only slightly related to DA, but is most concerned with heating of the cap, due to its losses. This includes DA, but also connection resistance and lead resistance. DF is important in switching supplies so that the filter cap does not overheat and explode.
ESR is again related, but is mostly concerned with the 'short-circuit' aspects of the cap, and how well it will pass signals without any drop across it.
These are approximations, and you all can quibble with me about them, but it is important to understand that they are not all the same thing.
DA was found to be important, first, in analog computers, popular in the 1950's. It was known to effect calculations, and was difficult to compensate for. It is also very important in sample and hold circuit operations.
Tantalum and ceramic caps can have lots of nonlinear distortion as well. Aluminum caps are better, but not perfect in this respect.
 
Old 19th January 2006, 11:14 PM   #118
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Quote:
Originally posted by Steve Eddy

So, what is the effect of DA on an audio signal? For starters, it's not anything like a U2 video.

se
How do you know what you assert? Not anything like ... ? Show me a picture or do your best to describe in words, then we can compare.

DA, or something to which DA corresponds or correlates---for simplicity's sake, what I'll call DA---smears and/or ghosts and/or adds to and/or subtracts from an audio signal. I hear DA's effects as a form of veiling and grunge, among other descriptions I could throw at it; veiling because DA disrupts my ability to hear clearly into instruments, spaces and dynamics, and grunge because I feel a sense of subtle relaxation or relief when DA is removed as if an irritation has been removed.
 
Old 19th January 2006, 11:21 PM   #119
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John, have you read Bateman's series of articles on the "Sound of Capacitors"? I found them to confirm what my ears and observations had told me about capacitors.
 
Old 19th January 2006, 11:29 PM   #120
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The effects of DA will not manifest themselves as reverberation, echo, or ghosting. These are reflections or repititions of complex AC waveforms. DA's mechanism is that of charge retention, and while the effects are not clearly understood... there is little if no potential for DA to store anything other than a decaying DC potential (not that this is good for audio... after all... DC relative to what?).

I do not argue with the fact that DA, and an as yet undescribed (but obvious) property of it, is probably the prime explaination for the percieve difference in capacitor sound... provided these differences do indeed exist.

 

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