Electrolytic Caps [Good or Bad?]

[R.G.]

Most of that I already knew.

Good! You're more informed than most people who own tube amps.

My opinion remains unchanged.

That's OK. As I said, I'll defend your right to have your own opinion, whether or not it agrees with mine.

You like to type, and you have lots of experience. But you are not as knowledgeable as you would like to be on electrolytic cap physics.

That's only partially correct. I kind of hate to type. I wish when I'd been in high school that typing was something that guys could have taken too.

I do have some experience, not as much as I'd like, but some.

And you are correct, I don't know as much as I want to about electrolytic capacitor chemistry and lifetime projection, which is what I think you meant instead of "physics". I always want to find out more about how things really work, so can you please enlighten me about what I may have missed in my write up?

[Diablo]

I don't know about you all, but I have a warm fuzzy feeling now that all of my amps have brand new e-caps in them. It's like an oil change for an amp.....

[guitician]

any amp..ever.

I withdraw this statement because it is obviously a mass generalization.

R.G. your right about the current state of e-caps, and the details of failure analysis are too broad to get into now.

Mfgs. used to make really good caps, and they were put into designs that let them last a very long time. That, sadly, is no longer the case in most of today's mass produced amps.

I've seen e-cap data sheets that spec. 50,000 hours at full temp. and ripple current. But they are extremely expensive. Some 105c caps I've seen at 10,000 hours that are not too expensive.

It is what it is. I guess I'll go open up a capacitor store.

[LarryN]

Bill Krinard of K&M Two Rock prefers old caps in his personal projects, but I'm sure he tests them first. I've also noticed the effect of being hit by high voltage at turn on in a circuit such as a vintage Deluxe Reverb, where the first two caps have been leaking the fluid. The caps further down the chain can sometimes be OK.

[R.G.]

Bill Krinard of K&M Two Rock prefers old caps in his personal projects, but I'm sure he tests them first. I've also noticed the effect of being hit by high voltage at turn on in a circuit such as a vintage Deluxe Reverb, where the first two caps have been leaking the fluid. The caps further down the chain can sometimes be OK.

I prefer the taste of mustard on egg-and-cheese sandwiches!

You can easily enough "dirty up" a new, good, low ESR cap any way you like.

You can add series resistance, like electro caps develop as they age. You can add parallel resistance, like electro caps which begin leaking as they age. You can even add series inductance if you want to try faking that. Then there is a whole long string of series/parallel networks you can do to make a new, low ESR/ESL cap sound like the oldest, nearest-to-death's-door cap you can imagine.

Even a dyed-in-the-wool anti-theoretical here-let's-try-another-one tweeker can home in on dirtying up caps, because it's only a one- or two-dimensional search.

Think about it though. The cap doesn't directly affect your amp's operation. The voltage on the power supply does, though. It's all well and good to say that they don't make them like they used to. It's quite another to understand *how* they're different, and thereby be able to do -whatever it is- in any application you want.

How do caps change as they age? Hmmm...
What do these changes do the the power supply voltage and current? Hmmm...

Just some ideas for thought.

[Diablo]

I don't know....maybe we're missing the ebay opportunities to sell some old....oops...vintage broken-in electrolytic caps.

While I'm sliding in this direction, can anyone explain the claims about film/foil coupling caps "breaking in"? Can anything really be changing in a film cap as you start applying some AC signal? I'm sure you've read the claims that "My whizbang 3000 authentic film capacitor requires 200 hours of use before it breaks in and attains sonic perfection". Any truth whatsoever to this?

[R.G.]

While I'm sliding in this direction, can anyone explain the claims about film/foil coupling caps "breaking in"? Can anything really be changing in a film cap as you start applying some AC signal? I'm sure you've read the claims that "My whizbang 3000 authentic film capacitor requires 200 hours of use before it breaks in and attains sonic perfection". Any truth whatsoever to this?

Interesting question.

My knee-jerk response is that it's the purest, most highly refined fecal matter that can be produced by talented, skilled and experienced advertising-artists and self-deluders.

The materials used in film-and-foil caps are just about impervious to aging on human time scales if they're moderately sealed from air and water. And we are, after all, dealing with people who claim to be able to hear differences in the sound of alternating current (i.e. "goes both directions in an alternating manner") depending on the direction of a copper-wire cable, and also claim to be able to hear differences in the sound based on the presence or absence of tiny impurities in copper wire.

However, I realize that I am knee-jerking on that, and that realization makes me cautious. The only possible break-in I can think of is that it is barely conceivable that the mechanical force between the foil electrodes is flexing the plastic insulator by microscopic amounts, and that this causes some change in the value of the capacitor by changing the actual thickness of the insulating regions and hence the capacitance, or possibly by work-hardening the metal film and that changing the spreading resistance microscopically. These are conceivable, I guess.

However, it is 100% certain that a great deal, perhaps most, of what we perceive of the external world is not directly "sensor data" in the sense of the signals our nerves feed into our brain, but rather a hyper-refined and signal-processed and multichannel integrated based on what the nerves send the brain. The human brain simply makes up the parts of the picture that the nerves don't send. And it will happily fill in not only little holes in the sense of the last few missing pieces of a jigsaw puzzle, but something more like the *entire* picture from one random piece.

Worse yet, the brain tends to make up the picture which has been suggested to it. These things are survival characteristics for humans in the real world, where a twig snapping or grass rustling may enable one of your ancestors to form a picture of a saber-toothed tiger about to spring. That same mechanism, when used for savoring audio, leads to a vulnerability to the lying, cheating, greed of other humans.

This is all a very long, roundabout way of saying that while I have no evidence that break-in in film and foil caps does not occur - no surprise, since it is logically impossible to prove a negative assertion - I see no positive data supporting the assertion that break-in does occur for these caps. And if I have to choose between these two based on data other than the word of a known-unreliable source (cork-sniffing sellers of capacitors) and the provable surety of the human ability to be suggestible and self-deluding, I'd fall back to a conservative position. I personally consider break-in on film caps to be in about the same class of facts as the existence of intelligent life elsewhere in the cosmos: Could happen, maybe; and there are lots of people who claim to have seen evidence for it and have become unshakable true-believers, but there is not one shred of repeatable data available to prove it.

So: if I am asked to believe in intelligent life elsewhere in the cosmos, my response is "Prove it.", especially if I am being asked to cough up money based on the belief.

And: if I am asked to believe in film-and-foil capacitor break-in, my response is "Prove it.", in the form of show me a repeatable and independently verifiable measurement that demonstrates that something about the capacitor changes after a few or few hundred hours of use, and even more importantly - after showing me such a change, 'splain to me how that change is always in the direction of "better sound". And simple statements like "I listened to my DonnerUndBlitzen Hyper caps before and after a 200 hour break-in, and at the end the sound was much creamier, while at the same time lower calorie and less filling."

The cynical part of me thinks that 200 hours is enough to get past any possibility of returning the turkey caps for a refund. That, my friend, is a real, provable, repeatable and measurable reason for a capacitor seller to support the break-in assumption.

The race is not always to the swift nor the contest to the strong - but that's the way to bet.

[Enzo]

RG - you sure like to type. And brother, keep on doing it, because something interesting, informative, and useful always comes out.

[Diablo]

The cynical part of me thinks that 200 hours is enough to get past any possibility of returning the turkey caps for a refund. That, my friend, is a real, provable, repeatable and measurable reason for a capacitor seller to support the break-in assumption.

The race is not always to the swift nor the contest to the strong - but that's the way to bet.

That is what the cynic in me was thinking too. I have a materials science background, and I was trying to imagine how the AC current could be interacting with dielectric film to make some permanent change in the film. You sure as heck aren't going to change the metal film by AC current.

I found a good scientific link with electrical properties of Mylar, as used in film capacitors. It's curious that they have no data on aging characteristics, so they must not be able to measure any change in properties with break-in.

http://www.audiocircuit.com/A-PDF/AA...____-B-A01.pdf

So at this point, this theory goes into the same category as cryogenic treatment of vacuum tubes....

[HTH]

I don't know....maybe we're missing the ebay opportunities to sell some old....oops...vintage broken-in electrolytic caps.

who's missing the opportunity

[tedmich]

The cynical part of me thinks that 200 hours is enough to get past any possibility of returning the turkey caps for a refund. That, my friend, is a real, provable, repeatable and measurable reason for a capacitor seller to support the break-in assumption.

There is a well defined psychological effect of growing acclimated to a new condition and overestimating the improvement when the memory of the past condition fades. Many modern enterprises take advantage of this human weakness, one of the best known being the 2-3 weeks of use requested by electric razor manufacturers before judging the effectiveness of their product. Rather than allowing your whiskers to be trained by the shaver, in reality you forget what a good shave your manual razor gave, reflect on the high price you paid for the new one and judge its performance much more positively.

Anything approaching a true A->B test is dangerous to many businesses; "break in periods" avoid a temporally close comparison and allow weak human psychology to take over.


Or maybe this:
" Break-in
Simply; The sound gets clear. It at first sounds smeared.

Technically;
Several things happen. The major thing is; during the break in period, the dielectric material (the insulating material) interacts negatively with the signal flow. The dielectric absorbs and releases energy as opposed to passing it through the capacitor. Uncooperatively, this is occurring at chaotic intervals.

This sporadic interaction is changing signal flow through the capacitor. However, the dielectric material changes over time as voltage is applied to the capacitor. The voltage creates heat, and a polarized skin forms on the surface of the dielectric (called skinning).

The dielectric then has a path through which to absorb and release energy, and does so at the correct times due to the formed path. (Like a path through a forest that is traveled over and over). Also over time, as voltage is applied to the conductors (the foil) the metal tempers, creating patterns as well (electricity will take the path of lowest resistance).

There are other reasons like skin effect (With an alternating current, there is a delay in the magnetic field's response to the change in current and the 'old' magnetic field tends to push the current towards the outside of the conductor. As the frequency increases, so does the effect until at very high frequencies the entire current flows in a very narrow skin on the conductor--hence the name).

One other consideration is self inductance (The property of self inductance is a particular form of electromagnetic induction. Self inductance is defined as the induction of a voltage in a current-carrying material when the current in the wire itself is changing). Although this is a non-inductively wound capacitor; meaning, careful attention is made to not produce inductance with the design, there is an inductance due to the alternating voltage.

Every electrical component has a break in period. Some are more noticeable then others. Signal carrying components are the most obvious. It will take approximately 100 hours of operation for the capacitor to function to full performance."

from Sozo WEB site

check this heated discussion on cap break in:
http://www.polkaudio.com/forums/showthread.php?t=65894


my vote is for psychoacoustic masking but I'm just a damned scientist...

[Rhodesplyr]

Most of my work has been on Hi-Fi amps, Hammond Organ, and Leslie amplifiers, and I have had to replace a LOT of high voltage electrolytic capacitors. In fact, I had one in a Dynaco MkIII amp blow up on me while I was very carefully attempting to reform it.

On the other hand, some do seem to last forever and still work well, so what gives?

In my experience, this can be answered with one word: HEAT. Where the capacitors are close to output tubes, rectifier tubes, or high-wattage voltage dropping resistors, they fail. On the other hand, if the chassis is well-ventilated, they last a long time, especially if the voltage rating isn't exceeded (as is the case in the Dynaco MkIII).

I'm not saying that that's the whole answer. Build quality definitely figures in. But heat practically guarantees failure. I just replaced a 30uF capacitor inside a 1963 Sherwood S-3000V FM tuner (crowded chassis) and checked it with my impedance bridge. When I finally got something close to a balance, it was 0.3uF. I had to re-stuff the main 4-section filter can to get rid of some hum, it's located in the center of the chassis and has sand-cast voltage dropping resistors all around it. On the other hand, this same unit has one 40uF electrolytic in its own small can right at the edge of the open back of the chassis. It's still fine.

In the H.H. Scott 299 integrated amp, they put filter cans right next to a 5AR4 rectifier. I've never seen an original one that wasn't shorted.

The first B+ filtering stages with solid state rectifiers are also likely candidates for failure as these get charged quickly at turn-on and see continuous high ripple current.

David

[guitician]

I guess the best sounds would be coming from a purely DC coupled amp/speaker run from a proton exchange membrane (PEM) fuel cell. Forget the caps altogether.

[Rhodesplyr]

Capacitor burn-in

I've observed the phenomenon of capacitor burn-in many times. In fact, now, before I install plastic film capacitors, usually polypropylene, I burn them in by hooking them across the house AC for a couple of days. I spoke to a capacitor manufacturer about it once, and they gave this method their approval. I used to experience that "brightness" of film capacitors when first installed, but this gets me past 90% of it. If, for some reason, I don't have time to do it, I can usually tell the difference.

And as someone with a Ph.D. in literature, I do think it's reasonable to use terms like 'brightness' or 'harshness' to describe sound because it's how we communicate our perceptions. At the same time, whenever possible, I like to try to understand the science behind it.

I discussed capacitor burn-in once with a graduate student in textile engineering who works with things like polyester and polypropylene on the level of their molecular chemistry. He said that something might very well be happening at the boundary of the plastic film and conductive foil layer as a result of the application of AC voltage, which does cause tiny amounts of motion inside the capacitor. For example, it could involve the dielectric conforming itself more closely to any microscopic irregularities on the surface of the foil. He also speculated that this could involve tensions placed on the film during winding.

Of course, precisely because it's something happening at a boundary layer inside a capacitor, it's going to be damn hard for anyone to document with high technical accuracy. You'd need a laboratory with very specialized equipment--and funding.

The "show it to me on an oscilloscope" argument is also b-s because I can often hear things better than my eyes can discern them on an oscilloscope screen. I'd dare someone to try to distinguish a medium-quality digital piano from a real piano based on a signal on an oscilloscope screen, even though it might dead bloody obvious to anyone who plays a real piano.

David

[guitician]

David, I'm an audiophile too and I've observed too that capacitors do sound different, in a way that is very noticeable, like between a real piano and a sampled one. I remember seeing some blind tests done where people were asked to tell the difference between digital recording and analog, and they couldn't. Some people hear better than others, that's for sure.

When friends visit my place and listen to CD's on my stereo system, they always complement me on how "real" it sounds. But, if they went to shop for similar sounding system, more than likely they wouldn't hear the "Quality" of the sound, from one system to the next. And then they would end up buying what the salesman said was the "Best" sounding system.

There's a lot going on with sound, and when audio designs are put together mostly by ear and trail and error, the results usually come out great.