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In Reply to: RE: How? posted by Lee of Omaha on May 15, 2016 at 10:33:14
A certain amount of energy builds up in the dielectric, over time. When things reach a "steady state", you notice it.
BTW, a certain amount of observed "run in" is associated with the listener getting used to what is being heard. I certainly will not guess where Physics leaves off and Psycho-acoustics begins.
Eli D.
Follow Ups:
I'm wary of hearing what you want, too. I don't think that's what going on here. I'm hearing detail and especially separation of instruments (not spatially, but in an indescribable way that is live-like, not recording-like. The only variable is the amps' burn-in.
I think there is some physics going on. "Magic" bothers me; I like to know the "why" of things. I was always a pain in the ass to my teachers because of that.
Lee
Dielectric absorption in coupling caps can't really affect sound in a bad way. Coupling caps are supposed to block DC while passing the AC signal so who cares if the DC gets absorbed into the dielectric.All the better I would assume.
Dielectric absorption simply does not affect the way a capacitor passes the signal. Dielectric loss becomes a problem when significant high frequency signal voltage appears across the capacitor, but is rarely even measurable as a loss at audio frequencies that we would listen to.
A friend you get for nothing,an enemy has to be bought
Dielectric absorption causes hysteresis, similar to magnetic hysteresis in iron cores of transformers. In both cases measurable distortion occurs. Mylar has high hysteresis, teflon is low. Ordinary iron has high hysteresis, nickel is low.
In my experience, both caps and iron components have a breakin effect, which can be confirmed by comparing two identical circuits, only one of which has been broken in without any listening (drive a resistor instead of a speaker). I have done this experiment, as have many others here I'm sure.
Fortunately for me :^) I am more an engineer that a scientist, so the observed fact is more powerful than the theoretical prediction. I would love to find a plausible reason for the breakin effect but I have not yet found one.
...if one considers the theoretical electrical model of DA, "smearing" of transients might be expected. It's not clear how audible this would be and I've never seen any definitive listening based studies addressing the issue. Since the DA model is relatively simple, I'm curious what a sim might show us, esp using a non-repetitive driving signal.
FWIW, the two types of caps with the greatest DA I've encountered are electrolytics of any nature and to a lesser extent, K40 PIOs.
I'm curious what a sim might show us, esp using a non-repetitive driving signal.That is what would be hard to measure in overall application because even tho paper in oil caps have a higher DA,some like Steve Bench have cited the fact they have very stable characteristics with freq change.
This goes back to one of my original points in that we typically do most testing with a single frequency at a time and simple logic tells us that we don't listen to just one frequency at a time.
Now lets say we drive a capacitor with a 20 to 20k sweep and monitor it on a PC thru an 8903 or just a nice audio analyzer in general,I wonder if we could spot any obvious conclusions like non linenerties or excessive distortion at different frequencies of one cap vs another? I would love to be able to measure real world conditions as used in an audio amp or preamp..I put caps on my Sencore capacitor analyzer and I can measure the most important aspects of the cap from an engineering standpoint but in audio use it can be tricky and sometimes things that are perceived as negative in the engineering world,can be a good thing in audio applications.
I would love to make some conclusive measurements as it pertains to our hobby..Help me set something up.
A friend you get for nothing,an enemy has to be bought
Edits: 05/16/16 05/16/16
I think psycho-acoustics is responsible for about 95% of the opinions around here. The other 5% are just psychos. :)
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nt
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