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Capacitor burn in ??

DEFTECHY

DEFTECHY

Well-Known Member
Mainly asking about electrolytic capacitors in a solid state amplifier. I just finished a full recap of a 1970's sansui integrated amp, used all lytics of the original values and no film caps like some do. Ive read about cap burn in and some say its needed and makes a difference & some say its not and makes no difference.

I have about 5 hours of playing music at mid volumes and while I "think" there is a difference or improvement in sound from the 40+ year old original caps, some of which were out of spec, I cant say I hear any differences from the first 5 minutes of use to now.

Just curious what others on AK think about it? Is there a benefit to burning in electrolytic caps on a vintage amp and if so, how much time is needed and has anyone actually heard a real difference in sound besides the all too common placebo effect?
 
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I believe it is a thing, but not to the extremes some claim - you know the kind of statement - "at 500 hours I could really hear the clash of the cymbals" - I call BS on that.

However I have experienced a lack of performance (i.e. flat sounding - lacking in dynamics), for as much as a week of on-off use of a newly restored amplifier. With a very definite improvement over this time, sometimes much quicker - just a couple of days, thereafter no change at all. This might be attributable to capacitors or anything else done in connection with the restore, including expectation bias, who knows?
 
This topic has been discussed many times over the years on AK, I've searched it up before myself.

Some people claim it's real, some people claim it's not real. I haven't experienced it.

Scientifically, it makes no sense to me. An oscilloscope that has been repaired with new capacitors doesn't measure more accurately once you let those caps burn-in.

As we all know, though, measurements aren't everything and music is a very subjective experience. I try not to discount other people's subjective experiences, but the claims "audiophiles" make are hard to take seriously a lot of the time. I once saw someone claim that polishing the pins on his power cord was one of the biggest improvements he ever made to his system and it was like a "wet blanket was lifted off of the speakers". C'mon dude, be for real right now. :rolleyes:
 
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Long unused 'lytics will undergo a forming process once pressed into service again, and this might affect S.Q. as it progresses. Film type caps will not change due to aging so long as moisture does not get into the dielectric and cause a leakage current to flow if there is a DC bias across the cap.
 
This often comes up and the debates on both sides rage.
My two cents is that I have worked in electronics since the 80's, in a wide variety of applications from radar to digital modems to e-beam tools and never heard one word about capacitor break-in except on audio forums.
 
RVT1K said:
This often comes up and the debates on both sides rage.
My two cents is that I have worked in electronics since the 80's, in a wide variety of applications from radar to digital modems to e-beam tools and never heard one word about capacitor break-in except on audio forums.
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Funny, that, hey? I worked in electronics and never saw anything about capacitors that audiophools worry about. Store some 'lectric, let 'er go later, done.
 
analogwisdom said:
This topic has been discussed many times over the years on AK, I've searched it up before myself.

Some people claim it's real, some people claim it's not real. I haven't experienced it.

Scientifically, it makes no sense to me. An oscilloscope that has been repaired with new capacitors doesn't measure more accurately once you let those caps burn-in.

As we all know, though, measurements aren't everything and music is a very subjective experience. I try not to discount other people's subjective experiences, but the claims "audiophiles" make are hard to take seriously a lot of the time. I once saw someone claim that polishing the pins on his power cord was one of the biggest improvements he ever made to his system and it was like a "wet blanket was lifted off of the speakers". C'mon dude, be for real right now. :rolleyes:
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There's probably something to the forming of electrolytics when first installed, but I raise an eyebrow at most of the claims.

The only area I've seen anything approaching audiophile levels of outlandish claims are nutritional supplements.
 
I've read from a person that swears after his SAE amplifier(s) have been re-capped they needed at least 400+ hours to fully be broken in and sounding great. The only thing I have heard was an improvement from a fully rebuilt crossover I had re-done, after about a couple hours or so. The amplifiers I had re-built had sonic changes from the bias being adjusted.
 
I’ve only ever done a couple “recaps” so far, but haven’t noticed any change (to my ears) after running them for a while.

I have, however, gotten the impression that after running a few units that have been sitting for a decade (or more) that they start to have a better (smoother maybe? Perhaps less “tinny”?) sound after a day or two with power on.

Nothing quantified or measured, just a subjective listening impression.
 
If your replaced caps that were meeting spec with new caps that are meeting spec it will result in very minor change if any at all. Replacing out of spec caps with caps that meet spec results in improvements in bass, treble, imaging and musicality.

You can prove by measuring leakage that burn in or reforming of electrolytic is a real thing but it happens in a few hours, not days or weeks. I once received a batch of 6 year old caps that would drop from 35v down to 10v in an hour after a brief charge but after reforming them by limiting the current to 5ma for 4 hours they only dropped to 28v in the 12 hours after reforming them. Cap manufacturers and even the military have documents suggesting that you reform capacitors that sit unused for years, and once again it happens in 1 to 4 hours not weeks or months.

Here is a link to a thesis someone did on the effects of reforming electrolytics, the results of pre and post reforming start on page 46, it shows leakage is drastically improved. I have received caps that were 4 years old from mouser and digikey so it also applies to new cap orders at times.

Without having a cap tester to know the health of the old caps its a crap shoot, just tested a receiver from 1975 and all its caps tested fine but I have also seen a receiver from 1989 that had over 40 caps that tested awful. Some recaps have resulted in drastic improvements and others made no difference and I felt I had just wasted a few hours and a few dollars. So now I trust my cap meter, test equipment and ears and if everything is fine I leave the old caps alone, more times than not there are at least 3 or 4 out of spec caps found though.
 
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I agree with those documents, I've heard the same changes some people describe: amps sitting unused for Long time sounding better after one day,and recapped units sounding better after some minutes, perhaps 1 hour or 2
 
elnaldo said:
I agree with those documents, I've heard the same changes some people describe: amps sitting unused for Long time sounding better after one day,and recapped units sounding better after some minutes, perhaps 1 hour or 2
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That makes sense to me. About the period of time you'd expect for electrolytics to reform.
 
In speaker crossover recaps, i've experienced huge changes in the 1st minutes. Installing everything, playing sound, and "ought, something went wrong", horrible sound for a while and starting to sound better after a couple of minutes. Also, customers telling me that a recapped speaker sounded worst than before the first days, they told me they waited a bit before complaining, and after a week, or 5 days at least, they started to sound really good, confirmed by other friends that didn't know about the recaps, they just said "what did you do to the speakers?, They sound way better than yesterday" and nothing was done. Just using them. I've heard this situation just from 2 customers among dozens of recapped speakers. In both cases the "break in" period was about one week. Perhaps just their hearing adapted to the new sound, I can't know.
 
DEFTECHY said:
Mainly asking about electrolytic capacitors in a solid state amplifier. I just finished a full recap of a 1970's sansui integrated amp, used all lytics of the original values and no film caps like some do. Ive read about cap burn in and some say its needed and makes a difference & some say its not and makes no difference.

I have about 5 hours of playing music at mid volumes and while I "think" there is a difference or improvement in sound from the 40+ year old original caps, some of which were out of spec, I cant say I hear any differences from the first 5 minutes of use to now.

Just curious what others on AK think about it? Is there a benefit to burning in electrolytic caps on a vintage amp and if so, how much time is needed and has anyone actually heard a real difference in sound besides the all too common placebo effect?
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You will get all kinds of responses. But basically it depends on how long the "new" caps have been sitting idle. But new caps regardless have to "form", and that amount of time varies widely. Small caps form very quickly, and larger caps can take longer. The number of "windings" can vary so the more, the larger the overall surface area takes longer. The forming process literally "smooths" out tiny imperfections in the materials. How much you will actually "hear" is a matter of perception. But even so, it's always from a few minutes (small caps), to less than a week for very large ones.
I always perform the initial voltage adjustments and scope analysis, and have a quick listen to make sure everything is fine. Then just set it aside powered on for a few days at idle without even attempting to listen for any changes to the "sound" just so the electrons are flowing. The only exception is, if I use them by customer request, are the Silmic silk paper caps. They are well known to need 40 to 80 hours to fully form and smooth out the sound. Those units sit powered up for a lot longer so the customer doesn't squawk about them. :biggrin:
 
Thanks for the replies, I know this subject has been debated before and I have read some on it, just wanted to ask for current opinions based on people who have done full recaps using mostly all electrolytics.

I have done quite a few speaker recaps, mostly on vintage klipsch speakers, speakers are very different than amps though since they dont see the same type of voltage as electronic components, especially amps. In my experience with crossovers using film caps, I havent noticed any improvements or changes after X amount of time, the changes I hear are basically instant compared to 30-40 years old low priced caps used in most mass produced mid-fi speakers. Also one of the big aftermarket companies that support these older klipsch speakers say that film caps dont burn in after x amount of time, if anything they have whats called self healing properties that happen in a matter of milliseconds or a couple seconds, they are made to meet the specs and that doesnt change after X amount of time except to drift away from the spec after many decades of use.

So for crossovers & film caps I say little to no burn in you can hear, any changes are likely placebo effect & your ears are "burning in" to the new crossovers, but for electrolytics in amplifiers I was just curious what others thought. Thanks again for the replies!
 
The Fuxtor said:
I wonder if anyone here who bought let's say for example, a new Marantz 2245 brand new in 1976(?) can remember if the receiver sounded better after those new caps burned in? I can't recall anyone ever stating a post like that??
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Back then I highly doubt it. I myself when I bought a Sansui 9090DB brand new didn't care and just cranked that baby up! :rockon: :biggrin:
 
I've rebuilt dozens, if not hundreds of amps/receivers and today is the first time I heard a difrerence after burn in. It's a Pioneer SX-1080 that I completely rebuilt. I listened for the first time on good speakers yesterday and was beyond disappointed. There are some models/brands that I prefer and think sound better than others, but this was different. It sounded terrible with no highs and muddy bass. Powered it on again today and let it play for a bit and it's night and day. I started using different low leakage caps so maybe that has something to do with it.
 
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