Do capacitors really need to break in?

Interesting idea. One would think some audio or brain researcher would have done experiments on this, some time, some where.
Possibly, though it's sometimes surprising what hasn't been studied (rigorously, at least) because there isn't funding to do so.

If the effects are fairly subtle - which they would seem to be - we're talking small percentage changes in the frequency response curve, harmonic distortion, etc. I think one would need some sensitive measuring eqpt. to measure this stuff, not just looking at rms voltages?
Yup. Something like this http://www.nti-audio.com/en/products/flexus-fx100.aspx would probably be ideal. I don't have one, but I work in a university that does research and development on surround sound, ambisonics, acoustics, etc., and there might be one -- or something like it -- that I can use. I'll nose around a bit next week and see what I can find.
 
Well having only recapped two sets of speakers I only have limited experience with this. The first set, Klipsch Heresy's were terrible at first, certainly no phycoaccustic stuff going on there, it was a jarring experience, strange squeals and such, made my head spin around to look at the speakers! Second set was my Altec's, they just sounder smoother, very nice.
As I mentioned in an earlier post, the big difference in recapping say a PS in a receiver and a crossover in a speaker is the applied voltage as a percentage of the caps rated voltage. Power supply rails are 80VDC so you install 100VDC caps. When you turn it on, almost the full rated voltage is applied to the cap.
Crossovers typically use 200 to 400VDC caps yet they may only see 1 or 2 volts in an efficient speaker.
My theory is that the low voltage may not be enough to bring the cap up to specifications immediately. I think something is happening at a very slow rate that may take only milliseconds when full rated voltage is applied. Hence the reason most consumer and industrial electronics work at 100% right from the get go.
What could happen in a cap to cause several loud obnoxious squeal's lasting just a brief time? I already had over 50 hours on my rebuilt Mac MC40 monoblocks, they sounded fantastic from the start. Sound even better on my Altecs.
I really believe that there is something that happens with some caps when they are charged with a very low voltage. I've seen it suggested more than once to charge up caps with a PS and bleed them off before using the caps in a crossover to speed up the break in process.
If someone wants to do some testing, I think it aught to be along those lines. Maybe a 1kz, 1v signal into a 400VDC cap and record it with a scope that can capture events. Maybe some fresh caps and some NOS caps as well as different style caps.
Lets get away from this nonsense that since test gear, TV's and most all electronics works well out of the box that every aspect of stereo gear should be the same. I don't know of ANY commercial or consumer product that routinely installs caps that are rated so much higher than the actual applied voltage. Were dealing with a rather unique set of circumstances here.
Circumstances that even cap manufactures probably never even test for.

BillWojo
 
Lets get away from this nonsense that since test gear, TV's and most all electronics works well out of the box that every aspect of stereo gear should be the same. I don't know of ANY commercial or consumer product that routinely installs caps that are rated so much higher than the actual applied voltage. Were dealing with a rather unique set of circumstances here.
In this and related threads, the possibility that "burn in" effects might be due to unused electrolytic capacitor re-forming has not been questioned.

However, commercial and consumer products regularly use capacitors in circuits where they never come near their design ratings (significant de-rating to reduce risk of failure is common) or anything near maximum voltage might only be achieved under unusual circumstances -- maximum volume, maximum output level, maximum frequency, highest-numbered settings -- or never, if a high-voltage rated (but common) component is simply the cheapest for the given application.

The difference between restoring typical consumer gear or test equipment, vs stereo amplifiers and recapping speakers, is that consumer gear -- like old televisions and VCRs -- and test equipment will usually have caps replaced with modern brand-name new stock, ordered from high-volume suppliers (Mouser, RS, Farnell, etc.) and therefore likely of recent manufacture. They won't need to be re-formed. New-old-stock electrolytics will be assumed to need re-forming, and so will be re-formed on the bench and/or the repaired unit will be brought up slowly via a dim-bulb tester or variac, so re-forming takes place before the unit is returned to service or to the customer.

Only vintage stereo amplifiers and stereo speakers are regularly recapped by owners or enthusiasts who may be purchasing and installing caps from boutique suppliers offering components of unknown age and provenance, and immediately return them to full service with the solder barely cooled -- or are having equipment "restored" by commercial recappers who may use decades-old shelf stock and release the gear with minimal testing. This may produce a situation where stereo gear is put into full service with capacitors essentially un-formed. Combine it with the relatively low-voltage AC applied to speaker crossover caps -- at least at low volume -- and I agree with you that speaker crossover caps are likely being put into use whilst needing to be re-formed, and are being re-formed slowly in use.

"Loud obnoxious squeals" are probably something else, though. No condition of a crossover cap -- bad or good -- should generate a signal. That sounds like some unrelated phenomenon, like oscillation in the amplifier or a problem with the source.
 
Dave, been playing this amp/source for over a year and it was the only time I ever heard it, it was like a flash, just a brief moment, several times. Might have been playing something with horns or other high pitched music.
It's funny, I never cared for horns or any other kind of brass instruments before, until I got horns. Now I search music with horns out, it's introducing me to jazz. LOL The weird path we follow in our music journey.
I'm building some new crossovers for my Altec's, copies of Model 19 crossovers. The new Solens caps I purchased are going straight in. On the other hand, the vintage oil filled caps that I have will need to be reformed. I'm going to compare the two cap types.
Most of these are 600V with a few being 1500V. I have a Power Designs power supply that outputs up to 60VDC. Do you think that will be enough voltage?
Thanks

BillWojo
 
Dave, been playing this amp/source for over a year and it was the only time I ever heard it, it was like a flash, just a brief moment, several times. Might have been playing something with horns or other high pitched music.
You're sure it wasn't something in the source that should be there, but revealed by the replaced crossover caps properly passing high frequencies to the tweeters as intended?
I'm building some new crossovers for my Altec's, copies of Model 19 crossovers. The new Solens caps I purchased are going straight in. On the other hand, the vintage oil filled caps that I have will need to be reformed. I'm going to compare the two cap types.
Most of these are 600V with a few being 1500V. I have a Power Designs power supply that outputs up to 60VDC. Do you think that will be enough voltage?
Re-forming is only required for electrolytic caps. Neither vintage oil-filled caps nor the modern Solens are electrolytic; the latter are polypropylene film.

However, electrolytic re-forming is normally done as close as possible to rated voltage without going over, through a current-limiting resistor to avoid overheating the cap. If you were re-forming 600v or 1500v electrolytics, 60 volts would be too low.
 
Thanks Dave, so no forming needed on the oil caps. Good to know.
Nope, I have a few test CD's that I normally play after modifications. Was probably Diana Krall or Dire Straits. CD's that I know all to well.
Thanks

BillWojo
 
I'm glad this thread is here, after fully recapping electrolytics in a receiver, it initially sounded great at first power up. One day later I turn it on and it sounds like complete ass...tinny, no bass, 'annoying' type sound. I get pissed and wonder why I just spent days messing with this vintage receiver...so I let it play for 2-3 hours (quietly). Go back in the room and turn it up, its sounds way better, like it should...there was a difference. I just hope that difference keeps improving...play it loud? that wiill be my next 'test'. This piece was all original 1978, had 40 year old caps. I used all Nichicon audio caps, at the same ratings...no idea if that is good or bad, time will tell I suppose.
 
I'm glad this thread is here, after fully recapping electrolytics in a receiver, it initially sounded great at first power up. One day later I turn it on and it sounds like complete ass...tinny, no bass, 'annoying' type sound. I get pissed and wonder why I just spent days messing with this vintage receiver...so I let it play for 2-3 hours (quietly). Go back in the room and turn it up, its sounds way better, like it should...there was a difference. I just hope that difference keeps improving...play it loud? that wiill be my next 'test'. This piece was all original 1978, had 40 year old caps. I used all Nichicon audio caps, at the same ratings...no idea if that is good or bad, time will tell I suppose.
It's good. :)
 
Western Electric holds the world's recommended break-in time on their 300 B's at 2,000 hours, but the tube has a useful life of 40,000.
I own 8 of them and had brochures from WE.
They also said they will last longer if run at .25 volts less than recommended for optimum performance.
Z-caps, which I also owned had a 500 hour break-in period.
 
It's myth, consider a 10,000uf 200v electrolytic. That's the functional spec when manufactured and should remain the same after 300 hours or the lifetime spec of the particular cap. My experience has been that my brain takes time to adapt to a different sound quality. My system sounds great until I hear something better.
 
Western Electric holds the world's recommended break-in time on their 300 B's at 2,000 hours, but the tube has a useful life of 40,000.
I own 8 of them and had brochures from WE.
They also said they will last longer if run at .25 volts less than recommended for optimum performance.
Z-caps, which I also owned had a 500 hour break-in period.
Is that new WE 300Bs or the NOS?
 
It's myth, consider a 10,000uf 200v electrolytic. That's the functional spec when manufactured and should remain the same after 300 hours or the lifetime spec of the particular cap. My experience has been that my brain takes time to adapt to a different sound quality. My system sounds great until I hear something better.

Myth ??

Study charge theory and capacitive discharge ..

Dielectrics..
All materials accept some level of charge and have a measurable discharge rate ..
The levels change subsequent to charge and in the presence of repeated charge .
The rate of stabilization varies with the conductance of the material ..

Certainly capacitors "burn-in" (stabilize) .. and yes, that burn-in is likely audible in some variable instances ..
As is capacitive discharge in proximity to the audio signal stream ..



.
 
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It's myth, consider a 10,000uf 200v electrolytic.
Break in time varies by dielectric. Perhaps that's the case with electrolytics, but more linear film and teflon based caps used today for signal duty in speaker crossovers and components do require some time.

For which very competent manufacturers observe that break in time is required for optimum performance. In the case of my Audio Research gear, the factory recommendation was 200-400 hours - which was not a concern for me.
 
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Seeing the developments between posting #211 from almost 5 years ago and the last few, this topic had a longbreak-in time and in the meantime, some of the associated equipment may have suffered break-out already;)
 
I don't know about break-in. I do know about bad capacitors. An hour ago one of the caps in my Maggie 1.7's crossover exploded with a loud bang emitting a copious amount of smoke

I don't mind replacing a bad capacitor. I'm just not looking forward to removing all the staples needed to peel the grill cloth back.

It will be treated like work. Monday morning I'll dis-assemble the speakers, peel the grills and check the value of the good cap and replace both. Parts Express, here I come.
 
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