captaink said:
If you over volt it, probably a second or two.
If you're talking about normal use, any capacitor polarizes within a few seconds. "Burn in" is just some audiophool myth, if not an outright marketing scam. If the latter, "burn in" lasts just as long as it takes to convince yourself that some uber-expensive thingamabob you bought actually makes a difference in how something sounds.
With every new amp (or cap) I notice the distinct smoothing out of the sound after a couple of hours of play. The shift is both noticeable with electrolytic cathode bypass caps & with filmcaps for signal coupling (I use mostly Russian pio and teflon).
A while back I did a listening test between Russian silver-mica caps (parallelled) and pio to choose the best coupling cap; one cap variety per channel. At first differences were subtle but after a few hours of play the sound between both was totally different: the pio's sounded really smooth while the mica's retained the harsh character both had at the beginning of the test... Either Russian silver-micas need very long burn-in or don't benefit from it at all, pio's improve dramatically after some hours.
Regards,
Simon
Klimon said:
With every new amp (or cap) I notice the distinct smoothing out of the sound after a couple of hours of play. The shift is both noticeable with electrolytic cathode bypass caps & with filmcaps for signal coupling (I use mostly Russian pio and teflon).
A while back I did a listening test between Russian silver-mica caps (parallelled) and pio to choose the best coupling cap; one cap variety per channel. At first differences were subtle but after a few hours of play the sound between both was totally different: the pio's sounded really smooth while the mica's retained the harsh character both had at the beginning of the test... Either Russian silver-micas need very long burn-in or don't benefit from it at all, pio's improve dramatically after some hours.
Regards,
Simon
Hi Simon;
However, you are right and sometimes when people sit comfortably, relax, switch on a nice looking amplifier...
They relax and listen to the music hearing all details. You hear transformers, tubes, resistors, capacitors, even wires... Wires connect transformers, capacitors, resistors, tubes...
Silver mica capacitors... Nice...
Actually Russian silver micas have very fast burn-in, they burn-in instantly so you don't hear differences waiting long. As soon as you switch them on they already sound decently! The same very short time is for Russian Teflon (Ftoroplast-IV) capacitors. They burn in instantly and sound decent. Russian military could not afford long burn-ins so they always ordered fast capacitors, resistors, and tubes.
But remember that they are fair! If some carbon comp or similar resistors sound harsh you will hear that harshness through Russian micas like you see through a pristine clean glass like a fresh clean water!
So, you hear transformers... tubes... capacitors... resistors... You hear everything! You've switched it on...You relax, sitting comfortably, listening to the music... Your amp looks nice!
You are absolutely right!
I use Jensen PIO, Auricap, Multicap RTX, and Mundorf Silver in my amps. Having said that, I have not really cared about "burn in" as there is immediate audible differences between them but nothing that was reported by some where they sound bad then sounds awesome in a couple of hundred hours of play.
Wavebourn said:
Oh come on now!
Neither the Russian military nor the US military would have recognized the kind of subtle "burn-in" issues being debated here, at least not for the general use of caps that they needed. Take it from a guy who designed a lot of radio and aerospace gear for various US agencies. And what's a "fast" cap or "fast" resistor? I've never seen a spec sheet for passive parts that had a "speed" parameter.
Brian Beck said:
Oh come on now!
Neither the Russian military nor the US military would have recognized the kind of subtle "burn-in" issues being debated here, at least not for the general use of caps that they needed. Take it from a guy who designed a lot of radio and aerospace gear for various US agencies. And what's a "fast" cap or "fast" resistor? I've never seen a spec sheet for passive parts that had a "speed" parameter.
Brian;
for more info on the topic:
http://nlp.snowseed.com/intro_inductions.htm
(search for the Triple Spiral of Milton Erickson)
I don't even know what a PIO is, and don't believe in burn-in for most things, but here are some facts. If you put a microamp meter on an electrolytic cap, you'll see high leakage when it's first powered up. The leakage will go down over minutes and hours, and might not reach it's ultimate low level for days or even longer. Audible? I can't say, but change, albeit small, is occurring.
Ceramic caps, especially with high dielectric constants, are subject to aging and poling effects, not to mention temperature. Hopefully you don't use them in the signal path, but they too will change over time.
Let's not even mention tubes.
One would never choose a Teflon capacitor as a standard for capacitance. Low dissipation factor maybe, if an air cap wouldn't do the job, but not capacitance. Why? Teflon can't be used in most structural applications because it flows. It isn't mechanically stable. Chances are, though I don't have documented proof of this, that the capacitance value would drift over the years. Standards are invariably made of very rigid materials.
If you look on a fine enough scale, nothing is perfectly stable and changes tend to happen fastest when a part is first put into service. For sanity's sake however, one needs to grasp that below a certain level, these things really are inaudible. As implied above, it's way too easy to fool yourself into hearing or not hearing the nonexistent.
Ceramic caps, especially with high dielectric constants, are subject to aging and poling effects, not to mention temperature. Hopefully you don't use them in the signal path, but they too will change over time.
Let's not even mention tubes.
One would never choose a Teflon capacitor as a standard for capacitance. Low dissipation factor maybe, if an air cap wouldn't do the job, but not capacitance. Why? Teflon can't be used in most structural applications because it flows. It isn't mechanically stable. Chances are, though I don't have documented proof of this, that the capacitance value would drift over the years. Standards are invariably made of very rigid materials.
If you look on a fine enough scale, nothing is perfectly stable and changes tend to happen fastest when a part is first put into service. For sanity's sake however, one needs to grasp that below a certain level, these things really are inaudible. As implied above, it's way too easy to fool yourself into hearing or not hearing the nonexistent.
Klimon said:
I'm sure you do notice something like that when putting new amps, or new VTs in service. After all, it does take some time for the bias to settle down when using new VTs. However, I keep hearing that AuriCaps require some 200 hours of use to "burn in". I replaced a 1.0uF electrolytic coupling capacitor in a solid state amp with a 1.0uF AuriCap, and I noticed a decided improvement immediately. That's what helped convince me that they're worth it. They didn't change any after that.
Something might have been changing, but was it the capacitors or something else? If it was a VT amp, then heating within an inadequately vented chassis could cause resistances to drift. Might even be worse in a SS amp since transistors drift quite a bit with temp. That could shift operating points and cause a different sound. Or, perhaps, one or more VTs are going a bit wonkey?
IMHO I haven't noticed any particular burn in with these caps or any PIO, but in some applications they sound subjectively "slow" and a bit soft/rolled off. (And no improvement was noticed over time.) I have never bothered to measure the d/a. esl or esr of one of these so I can't really say I know why. They seem to perform best in applications where the source impedance is relatively low (say CF or SRPP) and voltage swings are large. I prefer teflon dielectric caps frankly.
Conrad Hoffman if you want to talk about teflon flowing yes you are right it does.
The Technical term for this is creep but I can guarantee you that you will never see it happen.
This effect takes years and unfortunatly it happens to everything from steel to people.
As far a dieletric teflon is superb it's chemically inert with practically everthing and it does not absorb mosture like most other plastics.
If you have a teflon dieletric capacitor with a dielectric of a few mils thick (.001 inch = a mil) if that cap was exposed to a constant 200 degree fahrenheit enviroment for 50 years you would probably see a increase of the thickness by a few mils.
But last time I checked most chassis are not runnig at that temp so most of us won't have a problem.
Creep is an failure that requires time, pressure, and temprature to fail you decrease 1 and you have to increase the other 2 to make up the diffrence.
The pressure that would be effecting these is the gravity of the earth even if this is a seal cap with a fluid inside the pressure increase from the increase of temp would have no effect on this.
Nick
The Technical term for this is creep but I can guarantee you that you will never see it happen.
This effect takes years and unfortunatly it happens to everything from steel to people.
As far a dieletric teflon is superb it's chemically inert with practically everthing and it does not absorb mosture like most other plastics.
If you have a teflon dieletric capacitor with a dielectric of a few mils thick (.001 inch = a mil) if that cap was exposed to a constant 200 degree fahrenheit enviroment for 50 years you would probably see a increase of the thickness by a few mils.
But last time I checked most chassis are not runnig at that temp so most of us won't have a problem.
Creep is an failure that requires time, pressure, and temprature to fail you decrease 1 and you have to increase the other 2 to make up the diffrence.
The pressure that would be effecting these is the gravity of the earth even if this is a seal cap with a fluid inside the pressure increase from the increase of temp would have no effect on this.
Nick
nhuwar- my point was that most of the small effects people worry about are of little consequence, and that if you look hard enough, there are an almost infinite number of things that have to be investigated and dismissed. As for the Teflon, you're quite right about its good qualities as a dielectric. OTOH, it's wound under at at least some tension, and I'll bet if you measured one every week for a year, using something with decent resolution like a GR1615, you'd find it drifted in value by a small fraction.
Correct but you can also say the same about any cap from temprature change.
No such thing as a perfect dieletric materila with a 0 coefficient of thermal expansion or a perfectly manufactured smooth surface free of thickness anomalies.
The point I guess is we can dispute this tell we are blue in the face because this hobby revovles around your ears and there all diffrent.
Oh but conrad they can actually compensate for that by first winding the capacitor then then annealing it which relieves the stress in it and also makes it more thermaly stable.
Nick
No such thing as a perfect dieletric materila with a 0 coefficient of thermal expansion or a perfectly manufactured smooth surface free of thickness anomalies.
The point I guess is we can dispute this tell we are blue in the face because this hobby revovles around your ears and there all diffrent.
Oh but conrad they can actually compensate for that by first winding the capacitor then then annealing it which relieves the stress in it and also makes it more thermaly stable.
Nick
kevinkr said:
Kevin, here's an interesting observation. Like you, I prefer teflon caps. The other day, I took some Russian teflons, drilled a hole in them, injected Fluorinert, and the teflon windings absorbed the Fluorinert. The Fluorinert noticeably changed the sonics of the caps, giving them, from the uncritical listening I've done, a bit of that PIO softness. The caps also almost entirely eliminated sibilance, retained (increased?) their resolution and sound nicely musical to boot.
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