Electrolytic Caps [Good or Bad?]

[guitician]

I have many old amps and they mostly have the original electrolytic caps in them. They have very little hum and sound great. But, every time I read about people suggesting pulling the filter caps out of old amps, I scratch my head and think...why. If you think about it, the only time they really go bad is when the amp has sat for many years in a poor environment, and then, plugged in and they fail right away, with little doubt about what has failed.

[booj]

Exactly. I've replaced 40 - 50 year old caps in amps and checked them with a cap checker only to find out they are absolutely perfect. No leakage, no change in value, although they generally read OVER the rated value.
If the amp is used occasionally, theres no telling how long they will last.
This is just an opinion, of course, since I've only been working on amps for 40 years or so.

[guitician]

Thank you. I knew I wasn't imagining this. I think techs confuse the "Shelf life" of an electrolytic cap with their "Running life". In an amp that is designed correctly, and is used regularly, for how ever long, the caps wont be an issue. There seems to be a lot of "You may as well pull all the filter caps because they will go eventually" posted by people and it's just not true.

[tedmich]

Surely you have had to replace many bad old ELs right? Granted they may be replaced too often but they go south more than any other component except tubes. Perhaps recapping is the equivalent to re-immunizing your pet every year even though once is generally enough, cause vets have to make house payments too. And it usually does no obvious harm, which is the common criteria for many misspent dollars.

[Resonator Guy]

I am of two minds on this one, but generally I agree that if the amp sounds good, leave it alone. I recently got a 1977 Fender Silverface champ that was completely original. It even had the original Fender tubes, and it sounds magnificent. No hums or buzzes, just a real chimey sound.
I did recently recap a 1957 Supro Super that I have had for years. It still sounded good, with very little hum, however I thought I would try some new high quality caps in it and I was amazed. It now sounds so much better and is a good deal louder.
So I guess it can make a difference to recap, but I try to do it only when necessary.
It is all great fun though, isn't it?

[guitician]

Actually the most EL caps I've replaced were of low voltage types used as signal coupling caps. They are lousy for that application. Changing parts in any amp will make a difference, just like changing types of strings on your guitar. If they made a huge difference, then your old parts were of poor quality or damaged a bit by environment.

[guitician]

Potentiometers are worse than electrolytic caps for failure, especially the cheap low cost ones that are being used more and more by manufactures.

[Diablo]

I think it makes economic sense to replace all the small e-caps in the amp after so many years of service. They are inexpensive, easy to change out, prone to age-deterioration (like all e-caps), and some of them (like the bias supply caps) are critical to the amp not destroying itself.

[guitician]

Originally Posted by Diablo

prone to age-deterioration (like all e-caps)

Not when they are operated under optimal conditions. Also, all e-caps are not created equal. Yes, replace garbage, 5 cent, econo brand stuff. Quality e-caps should never need replacing an any amp..ever.

[Diablo]

Originally Posted by guitician

Not when they are operated under optimal conditions. Also, all e-caps are not created equal. Yes, replace garbage, 5 cent, econo brand stuff. Quality e-caps should never need replacing an any amp..ever.

Do you have a link to any manufacturer's data that shows his e-caps last forever when operated under "ideal conditions"? What conditions do you consider optimal? How does one identify a quality e-cap?

[guitician]

Be serious, no mfg is going to state that. Optimal would be either; always having voltage applied, or at regular intervals, and kept at temps below 77 degrees Fahrenheit. The better the seal, the better the cap.

[R.G.]

Originally Posted by guitician

Not when they are operated under optimal conditions. Also, all e-caps are not created equal. Yes, replace garbage, 5 cent, econo brand stuff. Quality e-caps should never need replacing an any amp..ever.

It may make for good wishful thinking, as in "... oh, Toto! Quality e-caps SHOULD never need replacing in any amp... ever!", but it's not realistic. Fact is, some portion of any brand, any amp, any age, will fail. Period.

Humans have the problem that they're more willing to believe anecdotes like stories typed into an internet forum than they are willing to believe the underlying math, especially statistics. That quirk is what keeps insurance and gambling industries in business.

The observed life for electro caps is predictable, statistically, just like the life expectancy of humans. Sure, there are humans who live to be over 100 years old. But the insurance companies can tell you pretty closely what the odds are of you personally making it there.

The fact is, repair techs replace failed e-caps a lot. That's where the predictions of life on caps come from at the cap making companies.

The issue is not really one of "how long can I run this amp before an e-cap vents and pours out smoke?" Instead, for the working musician, it's "This d#*d amp had better finish this set!" A working musician wants reliability and predictability more than long life. Or at least the ones smart enough to think about it do.

So people advise other people to change out caps. I do that, frequently. And I'll keep doing it, explaining if needed that you may be removing perfectly good caps. But those perfectly good caps may last perfectly good for five years, or ten more years, or five *minutes*. Recapping an amp nearing the conservative life expectation of the caps in it is not about draining every minute out of the old ones - it's about knowing that the amp will not have a cap failure on the new ones for a good long time.

Originally Posted by booj

Exactly. I've replaced 40 - 50 year old caps in amps and checked them with a cap checker only to find out they are absolutely perfect. No leakage, no change in value, although they generally read OVER the rated value.
If the amp is used occasionally, theres no telling how long they will last.
This is just an opinion, of course, since I've only been working on amps for 40 years or so.

Good opinion. I defend your right to have it. However, I also defend my right to think it's incorrect.

What you typed is factually correct.

If the amp is used occasionally, theres no telling how long they will last.

There is, literally no telling. It may be 50 more years, it may be five minutes, or the next power-on surge. The statement is literally correct, but not true in the semantic sense that it implies. The only way to tell is to look at the sum of the usage conditions and the statistics for that type/brand/lot number of caps and then ... guess. Caps on a shelf go bad. That's why they're a shelf life item. Using them with a voltage in the upper third of their specified voltage tends to keep the oxide layer repaired by leakage currents electrochemically where shelf sitting would make it degrade more. The occasional use also mitigates against short life by having few power on/off cycles and less overall hours of thermal stress. It's like heaven on earth for a cap.

But musicians want to PLAY these things, and working musicians want them to work every time. That's a little different.

This is just an opinion, of course, since I've only been working on amps for 40 years or so.

I've been working on amps on and off for only about 35 years, and haven't made a living at it. I made a living designing and supporting manufacturing of power supplies, so I've seen a LOT of caps used in power equipment, and I've had to understand the math and producers' data on projected lives of power components. I've also talked to a lot of other techs who repair amps, and I get a lot of agreement with doing recap jobs where an owner wants reliability.

I've also had a lot of feedback from owners who took my advice to have the amp recapped. Very often the comment is that the amp sounds amazingly better. Old caps, even ones that don't leak, have drifted values and high internal resistance. That changes the power supply impedance and the sound of the amp. Changing the caps out restores the power supply operation to the way it was when the caps were newer.

I recommend you borrow or rent an ESR meter. It's pretty easy to pick out which caps will make a big difference in sound by testing ESR, not capacitance or leakage. Old caps have higher ESR even if they don't leak and have the same capacitance. It makes a difference.

No one can predict exactly which cap is going to live for another decade. But if you want your expectation that the next time you turn on your amp it's going to play just fine, and the time after that, and the time after that, it makes sense to replace parts which have a built-in failure mechanism, *as admitted by the makers of those parts* every so often so you don't have to have the unpleasant opportunity to play air guitar in front of a crowd.

One of my favorite paraphrased proverbs runs "The race is not always to the swift, nor the contest to the strong; but that's the way to bet."

[tedmich]

point made!

[guitician]

Most of that I already knew. My opinion remains unchanged. 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.

[guitician]

Originally Posted by tedmich

point made!
[img][/img]

Yeah

[R.G.]

Originally Posted by guitician

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]

Originally Posted by 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.]

Originally Posted by 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.

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.]

Originally Posted by Diablo

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]

Originally Posted by R.G.

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]

Originally Posted by Diablo

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]

Originally Posted by R.G.

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]

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.

[R.G.]

Originally Posted by tedmich

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.

I think that's exactly correct - so correct that the hifi tweakos will do anything to discredit A-B-X blind testing, including pointing out that the results usually fail to find any differences between whatever is being tested. Rather than take that as an important result, they try to discredit the test. Classic political manuvering, even if unconscious. Remember, "no difference observed" is as valid a result as "A>B" or "B>A".

I personally view the refusal to accept results of double blind testing as a comment about the person doing the refusal - but that is just my opinion.

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.

OK, how much money would you bet on being able to identify broken-in versus non-broken-in capacitors which are otherwise identical, over a range of capacitors, multiple tests, in a double-blind test designed to isolate you from any pre-information, at a rate that's statistically better than random guessing?

Then remember that sales droids are betting tens of thousands of dollars on your NOT being willing to do that. Or able to do it if you were willing.

...whenever possible, I like to try to understand the science behind it.

Me too. But I had to earn a living understanding 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.

I've discussed this and similar issues with graduates in materials sciences for electronics over some decades. I guess it depends on who you want to believe.

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.

Who said anything about appearance on an oscilloscope? I said "measurement". Oscilloscopes are an indicator, but no, you can't for instance distinguish 0.1% distortion from 0.001%; well constructed A-B blind testing will do this. So will a well designed distortion analyzer. The bottom line here is that the well-documented tendency of a human to self-delude requires that the human have every bit of expected results and foreknowledge of the test removed to be *capable* of rendering an impartial verdict. That's *why* double blind tests were devised: not only do the testing subjects who give an opinion on the subject being tested have to be kept blinded about the test, the humans administering the tests have to be kept blinded about each test case to avoid them *unconsiously* telegraphing information to the test subject. Go google "Clever Hans" the horse.

If you ask a professional in medical or psychological testing, they will tell you about testing where humans have to render an opinion about what they perceive. And double blind testing. Note that Clever Hans' exposer himself could not *stop* delivering cues to Hans even when he knew what was happening.

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.

Yep, the o'scope is a low- to mid-fidelity tool for testing audio quality. That's why it's not used for that.

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.

Tee hee! See above. Clever Hans and other early episodes in psychological testing were incredibly important in understanding human perception testing. Humans simply cannot, on a reliable basis, produce accurate perceptual data if they have any cue whatsoever what is being tested or how. They cannot get around their internal expectations and biases even if they are consciously trying to invalidate those biases. And yet, they persist in saying that not being able to tell the difference on an audio taste test invalidates... the test (!?).

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.

I completely agree. It's totally consistent that this would happen.

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.

Hmmmm... so a not-formally trained person puts together audio systems by trial and error, not trying to avoid their internal biases, and they usually come out great? I'm going to guess that if a person is invested in "those experts" being wrong all the time, that they probably do add extra weight to an untrained person's coming out ahead.

What a surprise.

I realize that I'm just talking here. My experience over decades is that no one who has bought into audiophile subjectivism is capable of recovering. It just doesn't happen.

[Old Tele man]

...FIX what's broken...let SLEEPING dogs lie.

...simple: potentiometers "wear" out, electroytic capacitors "dry" out(*)







(*) --"other" failure mechanisms exist, but that's your job to learn about them.

[guitician]

Originally Posted by R.G.

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.

So, for someone to react to the "Perceived" change in a caps sound, there would have to be a real "rustle" or "snap", or then those changes would have gone unnoticed. I find it hard to believe that all these listeners are delusional.

Originally Posted by R.G.

Hmmmm... so a not-formally trained person puts together audio systems by trial and error, not trying to avoid their internal biases, and they usually come out great? I'm going to guess that if a person is invested in "those experts" being wrong all the time, that they probably do add extra weight to an untrained person's coming out ahead.

Hmmm... so the experts never listen to and adjust their designs afterwards?

[Prairie Dawg]

Originally Posted by R.G.

What a surprise.

I realize that I'm just talking here. My experience over decades is that no one who has bought into audiophile subjectivism is capable of recovering. It just doesn't happen.

Such a cynic. I am quite sure that the International Brotherhood of Carthusian Bauxite Miners (a little known offshoot of the Knights Templar) which only mines the finest aluminum for capacitors during certain phases of the moon would disagree with everything you say.

What was it Tug McGraw used to say, "You gotta believe!"?

[Rhodesplyr]

I realize that I'm just talking here. My experience over decades is that no one who has bought into audiophile subjectivism is capable of recovering. It just doesn't happen.[/QUOTE]

Of course, that's just your subjective experience ;-)

I once replaced the original silicon diodes in an early 1960s Dynaco SCA-35 with current production soft-recovery diodes, on the theory that the current ones are lower-noise. The improvement in sound was so pronounced, it surprised me. So, I tried the same thing on the bridge of one of my Leslie 122s--no difference whatsoever. I was predicting some change, but I perceived none. Bandwidth limitation in the Leslie or just no difference? I don't have an explanation.

Speaking of bandwidth limitations, I've had my hearing checked a few times, most recently when being fitted for a new pair of on-stage hearing protectors. I can still "objectively" hear to ~23kHz. I do hear things other people don't. Perhaps, psychologically, the denial of the subjective perceptions of some by others is displaced resentment at their inability to perceive things that others do. If you're going to invoke psychological mechanisms, let's open the door to all of them ;-)

I would take the bet that I could repeatably distinguish pre-burned-in vs. non-burned-in examples of the same brand of, say, Panasonic ECQP 0.1uF coupling capacitors in the same amp, under conditions where all other factors were controlled under A-B-X testing.

I've talked to materials experts who say burn-in is reasonable, and you've talked to those who say it isn't. Thus, there seems to be some disagreement about it even among objective scientists.

On the other hand, I do NOT own $1,000 power cords or write extensively about the sonic superiorities of silver wire over copper. Someone asked me recently what I thought about cryogenically treated tubes. I responded that I guessed they were "cool," but that was about it. I had someone tell me recently that it was vitally important to install a $30 Jensen copper foil in oil capacitor and cloth-insulated wire inside a Stratocaster for the best tone. I remain skeptical.

In general, I try to maintain some balance between science and subjectivity. One of the things I've written about in my academic career is the appearance of the medical expert in the 19th century. If you want to read some crazy "science," pick up a 19th C. medical textbook and see what was regarded as objective fact by "experts." Or read Charlotte Perkins Gilman's famous short story "The Yellow Wall-paper."