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Is The Running In Of Electronics A Myth?

Purite Audio said:
This is according to the technical director of Mundorf and Clarity Caps, the Mundorf guy thought that perhaps a small current through an over specced cap 'could' change, he had no proof though.
Clarity Caps also sponsored a study with the University of Cardiff studying ESR ,again couldn't find any correlation .
Keith.

( free range caps may be different though ? )
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Well this is correct for Film dielectrics - I keep referring to the Organic "Wet" type dielectrics... You can watch there leakage current drop over hours!!!

Also - I believe its the change in ESR with temperature that's most pronounced.
 
davidsrsb said:
Electrolytics are only well understood for reasonable bias. Behaviour at zero or near zero bias is not widely documented
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Except that its bad and best avoided - and thus always recommended to have a DC bias voltage for the most linear AC operation.
 
John,

Do oil film caps tend to last for decades? I have a pair of old Tannoys from the late 1950s and their crossovers, which have oil film caps, have never been serviced.

Probably well run in, though. :)

Joe
 
Hi Joe,

Joe P said:
Do oil film caps tend to last for decades? I have a pair of old Tannoys from the late 1950s and their crossovers, which have oil film caps, have never been serviced.
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I'm sure that John will be along shortly to offer you his more learned opinion, but from experience of experimenting in that area with my own Tannoys, I can say that PIO caps, when used in loudspeaker crossovers, aren't as stressed as when used inside amplifiers of that vintage, and so are less liable to drift wildly out of spec or fail.

That said, the PIO caps you've got in your speakers are still around 60 years old, and so could most likely do with being replaced. Just be careful that what you replace them with doesn't alter their sonic signature too much (i.e. the sound that you've grown accustomed to like), especially as vintage PIO caps sound rather different to the polypropylene types produced these days.

Vintage caps (PIO or electrolytic) do tend to have a certain 'addictively musical' sound of their own, largely absent in their modern counterparts. In that respect, when you decide to change the caps in your speakers, you may prefer to source some NOS originals on ebay (which turn up from time to time), and ensure that the seller has the capacity to measure them and confirm that they're still performing to spec. If so, then using these will help ensure that the 'voicing' of your speakers remains the same.

Failing that, seek some advice from those who've experimented with changing caps on vintage Tannoys, as to which ones are liable to produce the sound that you're after. Hope this helps :)
 
Joe P said:
John,

Do oil film caps tend to last for decades? I have a pair of old Tannoys from the late 1950s and their crossovers, which have oil film caps, have never been serviced.

Probably well run in, though. :)

Joe
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Hi Joe,

Basically I agree with Alan, the main problem with PIO capacitors is they get leaky both physically and electrically...

Problem is modern film caps will sound very different (which maybe a good or bad thing)...
 
Thanks, dudes.

The Tannoys sound spiffy -- awesome, in fact -- so I'm inclined the leave the stock crossovers unmolested. But I sometimes wonder if I'm not hearing them at their best.

(My other issue is having the tools to crack the crossovers open to do the surgery.)

Joe
 
Joe Hutch said:
It's not something I've ever experienced (as in 'this product sounds shite at switch-on, but 3 hours later it really sings' or 'when I first heard these speakers they made me claw the walls, but now, six months later, you would have to prise them from my cold, dead hands'). But then I'm pushing 60 and probably not 'discerning' enough to notice such things.
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I'm past 60 and have owned many varied amps and speakers and i am convinced that the burn in is not within the components but it is our own ears and brain adjusting to the sound.
 
I've built quite a number of valve an solidstate amps. I've barely noticed any burn-in with solidstate but with valves I've found the first 30 mins sees a big change and then the next 2 to 5 hours sees a smaller change. I suspect high voltage capacitors and OPTs are to blame but I don't know for sure.

Some coupling capacitors can take 20 hours or a bit more to totally come on song but mostly they are 95% there straight away, equipment warming up is more important IMO.
 
Keith, both the partys you mention only make film caps, so one would assume that is what they are referring to. Also having read the entire Clarity cap paper I know they make no reference to the forming duration of electrolytics.

Not that them saying the opposite of what i stated would in any way invalidate the experience I and the 300 odd or so builders of the Paradise pcb's have. It's just a science fact, electrolytics can take tens of hours to form.
 
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