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Old 28th April 2009, 07:58 PM   #21
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Quote:
Originally posted by jitter
So I know for certain that there are physical changes after a burn-in. Yet they are so incredibly small in that device that I can't believe they would be audible in the audio range. Who's gonna hear a 0.0002 V increase in non-linearity?
I'm not talking about 'large' differences, mostly a new product will sound harsh to me, which may disappear after a while. Some equipment never get better though.

Speakers should be played-in before evaluating, I've heard very noticeable changes, although I believe that is a more mechanical effect.
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Old 29th April 2009, 12:45 PM   #22
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As some of you may know I sell Audience capacitors in the UK, including their Teflon range. A great deal of Audience's information on this range is focussed on burn-in processes and proposed timescales, which they regard as absolutely vital.

And I personally don't believe a word of it. I simply cannot understand what actual process a teflon capacitor CAN undergo during this burn-in period. Would it be chemical? physical? electronic? thermal? parapsychological??????

With electrolytics I agree with what has been said above with regard to reaging/reforming, but in the case of electrolytics we are talking about a very well understood electro-chemical process which is inherent to the make-up of the parts. And in any case 30 minutes normally does it (not 720 hours or whatever is required for Teflons).

All sounds like hocum/voodoo to me, and I would have to strongly agree with the thesis...!
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Old 29th April 2009, 07:57 PM   #23
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Quote:
Originally posted by MCampbell
And I personally don't believe a word of it. I simply cannot understand what actual process a teflon capacitor CAN undergo during this burn-in period. Would it be chemical? physical? electronic? thermal? parapsychological??????
"I don't understand it so it can't exist." That will ensure that you never learn anything new.

At least try to listen before making up your mind, you may just get a surprise.

André
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Old 29th April 2009, 08:31 PM   #24
Atilla is offline Atilla  Norway
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"Hand-wound, hand-soldered and hand-tested...."

I don't know Matt, for quite a few things I'd excusively rely on the hand-made part. I'd bet my life on some of the hand-made trafos I've used, tested and demonstrated in front of me in conditions that should be made illegal. But when it comes to components requiring precision and certain levels of air purity to manufacture, I'm a little more skeptical. /end-of-direct-reply

I guess we all forget that caps quite often have unacceptable tolerances. It's so often people get hyped over the value of a nF to uF cap, forgetting some of the caps they get will go as bad as 20% tolerance. In fact, some of the caps that are very famous for their other characteristics - ESR, ESL, ripple current have abysmal tolerances.

So, you just installed the "very best" TM caps somewhere in your signal path. You burned them in for 600 hours. They're awesome....

Except that .. you know .. the left is 7.5% above its rated value and the right one is 7.5% under its rated value.

But everything is awesome, cause you *burned them in* TM. yesno?
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Old 30th April 2009, 04:21 AM   #25
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Quote:
Originally posted by MCampbell
As some of you may know I sell Audience capacitors in the UK, including their Teflon range. A great deal of Audience's information on this range is focussed on burn-in processes and proposed timescales, which they regard as absolutely vital.

And I personally don't believe a word of it. I simply cannot understand what actual process a teflon capacitor CAN undergo during this burn-in period. Would it be chemical? physical? electronic? thermal? parapsychological??????

With electrolytics I agree with what has been said above with regard to reaging/reforming, but in the case of electrolytics we are talking about a very well understood electro-chemical process which is inherent to the make-up of the parts. And in any case 30 minutes normally does it (not 720 hours or whatever is required for Teflons).

All sounds like hocum/voodoo to me, and I would have to strongly agree with the thesis...!

not to mention that teflon caps are temperature sensitive. between 25C and 100C, teflon undergoes at least 2 solid phase changes, i.e. the polymerized molecules change their configurations, and so change the characteristics of the dielectric. if you look at a temp/dielectric constant graph of teflon it changes at least twice in the 25-100C range, this also is reflected by abrupt changes in the cap's tempco as well. i was researching teflon caps for an oscillator for use in harsh environments a few years back, until i found out what the temperature characteristics of teflon were. while the molecules remain stable in the sense that the material doesn't decompose at high temperatures, the polymers undergo several phase changes from one stable state to another as the temperature changes, and the dielectric characteristics change accordingly.
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Old 30th April 2009, 07:47 AM   #26
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Quote:
Originally posted by unclejed613



not to mention that teflon caps are temperature sensitive. between 25C and 100C, teflon undergoes at least 2 solid phase changes, i.e. the polymerized molecules change their configurations, and so change the characteristics of the dielectric. if you look at a temp/dielectric constant graph of teflon it changes at least twice in the 25-100C range, this also is reflected by abrupt changes in the cap's tempco as well. i was researching teflon caps for an oscillator for use in harsh environments a few years back, until i found out what the temperature characteristics of teflon were. while the molecules remain stable in the sense that the material doesn't decompose at high temperatures, the polymers undergo several phase changes from one stable state to another as the temperature changes, and the dielectric characteristics change accordingly.
Now that is information that is totally new to me, and could, I guess, be a possible justification for burn-in.

Out of interest, what dielectric did you eventually select for the oscillator caps?
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