1audio said:
Electrolytics are asymmetrical devices, it's a completely different story.
Never thought about biasing DA materials, I think you may have something here, I think it's theoretically possible this way to reduce the DA nonlinear distortions. Unfortunately, in practice, high DA is almost always correlated with a DC conduction mechanism, with a much higher contribution than the standard Fowler-Nordheim tunneling, traps hopping, etc... mechanisms. Otherwise said, you reduce the DA impact but you got higher DF.
syn08 said:
DF = dissipation factor? Your suggesting that the DF increases with bias for some materials? Could that effect be used as an RF attenuator?
And to make sure I'm not totally confused about DA materials. Are those specific materials or is the mechanism present to some degree in all dielectrics (non-conductors)?
syn08 said:
I don't know about DA inducing linear distortions but perhaps the most commonly talked about linear distortion in audio is caused by speaker enclosure diffraction.
According to Earl Geddes, it's effect is pschoacoustically opposite to non-linear distortion in that it's masked at low SPLs and becomes more apparent at high SPLs.*
This is why Geddes insists his speaker enclosures (including waveguides) have roundovers on all corners and edges due to the corresponding physical size of enclosures and higher frequency wave lengths. The intent is to reduce diffraction products.
The differences in signal delay caused by speaker diffraction can be less than a millisecond.
Are there linear distortions produced by electronic audio gear which might sit in less than ms time frames?
* http://www.gedlee.com/downloads/AES06Gedlee_ll.pdf
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Hunches don't carry much weight around here but I think, due to linear distortions, many listeners don't listen to their systems at anywhere realistic levels because the sound just gradually becomes more unpleasant with SPLs higher than say, 80 - 85 dB. And, they unconciously limit their listening levels accordingly. (Who knows how much hearing damage has been prevented by this limiting mechanism?)
I expect this is mostly due to diffraction products but once these anomalies are reduced, then weaknesses in other parts of the audio chain may become more apparent.
Well, SYN08, here is a reference:
'REAL-WORLD AUDIO WAVEFORM ASYMMETRIES AND THE EFFECT ON THE AUDIO CHAIN'
Presented at 55 conv. AES oct,1976 Preprint No 1193
by W.L. Hetrich , National Public Radio, Washington, D.C.
Example:
"Figure 7. Female voice saying the word 'intangible' Asymmetry is 14 dB more positive than negative.
Figure 8. Same Female voice in a different mood using a different inflection saying the word 'seven' Asymmetry is 14 dB more negative than positive."
'REAL-WORLD AUDIO WAVEFORM ASYMMETRIES AND THE EFFECT ON THE AUDIO CHAIN'
Presented at 55 conv. AES oct,1976 Preprint No 1193
by W.L. Hetrich , National Public Radio, Washington, D.C.
Example:
"Figure 7. Female voice saying the word 'intangible' Asymmetry is 14 dB more positive than negative.
Figure 8. Same Female voice in a different mood using a different inflection saying the word 'seven' Asymmetry is 14 dB more negative than positive."
Modern broadcast equipment uses allpass filters to reduce these
asymmetries.
See these articles:
http://tinyurl.com/ctnsgp
http://tinyurl.com/c5pphh
ZAP
asymmetries.
See these articles:
http://tinyurl.com/ctnsgp
http://tinyurl.com/c5pphh
ZAP
But then again this manufacturer states that biasing a (non-polar) capacitor reduces distortion in his speaker crossover cap, read the section CPC technology: http://www.6moons.com/industryfeatures/omega/omega.html
Bateman's writings available here :
http://uk.geocities.com/cyrilb2@btinternet.com/downloads_4.html
http://uk.geocities.com/cyrilb2@btinternet.com/downloads_4.html
Hi FrankWW
---I don't know about DA inducing linear distortions but perhaps the most commonly talked about linear distortion in audio is caused by speaker enclosure diffraction.
According to Earl Geddes, it's effect is pschoacoustically opposite to non-linear distortion in that it's masked at low SPLs and becomes more apparent at high SPLs.*
This is why Geddes insists his speaker enclosures (including waveguides) have roundovers on all corners and edges due to the corresponding physical size of enclosures and higher frequency wave lengths. The intent is to reduce diffraction products.
The differences in signal delay caused by speaker diffraction can be less than a millisecond.---
I made some experiences with large baffles (2' wide) and various corners intended to avoid diffraction : I ended with something similar to Olson's L shape which I found giving better overall stereo effect and localisation of instruments.
I recently had emails with Keith Howard about his article :
http://stereophile.com/reference/704cutting/
He encourages me to make attempts to reduce baffles diffraction more popular. I am glad to see people more and more considering the importance ot the very neglected effects of secondary emissions of baffles within less than 1 mS.
---I don't know about DA inducing linear distortions but perhaps the most commonly talked about linear distortion in audio is caused by speaker enclosure diffraction.
According to Earl Geddes, it's effect is pschoacoustically opposite to non-linear distortion in that it's masked at low SPLs and becomes more apparent at high SPLs.*
This is why Geddes insists his speaker enclosures (including waveguides) have roundovers on all corners and edges due to the corresponding physical size of enclosures and higher frequency wave lengths. The intent is to reduce diffraction products.
The differences in signal delay caused by speaker diffraction can be less than a millisecond.---
I made some experiences with large baffles (2' wide) and various corners intended to avoid diffraction : I ended with something similar to Olson's L shape which I found giving better overall stereo effect and localisation of instruments.
I recently had emails with Keith Howard about his article :
http://stereophile.com/reference/704cutting/
He encourages me to make attempts to reduce baffles diffraction more popular. I am glad to see people more and more considering the importance ot the very neglected effects of secondary emissions of baffles within less than 1 mS.
john curl said:
I sifted through the article and unfortunately I failed miserably in understanding how is this related to DA, "linear distortions", etc...
The conclusion seems to be: audio broadcasting equipment need more headroom. To which I may fully agree, but it's irrelevant in the context of the current DA discussion.
syn08 said:
I think if you tie this back to some of the residual waveforms in the cap nulling tests that John and Walt did you will see the connection. I found that tenuous at best. There was some argument about preseving/changing waveform assymetry.
The fact that filtering can dramaticly change signal crest factor is well known.
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