The truth about caps

[R.G.]

I have no cap tester. I don't know.

We run into this with effects a lot. People will try some caps which have the same number printed on them, and come to some conclusion. The brand of cap which sounds better then becomes the Holy Grail Cap, when it's 10% or more different from the capacitance of the UN-holy grail cap.

Maybe it is in my own mind. Keep in mind I entered this as somewhat of a skeptic. So while perhaps there is a bit of a confirmation bias in my mind since I did pay money for the caps and wanted them to work, I certainly didn't expect to hear a difference. Perhaps if someone were to reimburse me for the caps, then things would change?

I may have mentioned Clever Hans the horse; I think I did. The problem with any internal bias is that you can't compensate for it even if you know it's there. Every aspect of a taste test matters to the opinion of the person testing; paying for caps, putting them in yourself, time since the last test, color of the cap, every thing. Having read some of the reasoning behind the way psychological testing is done, I tend to err on the side of thinking that a fair test by one person is almost impossible, and not because the person is uneducated, biased, or malicious. Instead, it's because they're human.

A double blind A-B test would have been ideal, but then of course I'd need an exact replica of the clone I built (with parts that measure all the same, natch.) Or I could have come up with some complex system of switches to switch the new ones out and the old ones in.

Yeah. The problem with good testing methods is that they're HARD to set up right, and expensive in money, time, or both.

Also ideal would have been measuring each cap to ensure they were of the same value, and then viewing the signal on a scope and providing the traces for everyone.

The problem with that is that scope traces don't show you what you hear. Frequency analyzer or Fourier transform spectra come closer. Again, it's hard to do well. This is one valid reason that the hifi tweekos have for not doing proper testing. Not the one they say, but a real one they don't say.

It starts to get pretty absurd, doesn't it? Even then someone would make the claim that I slightly rerouted some wire or fixed a bad solder joint or heated a component one too many times. That's the way it is with these sorts of things. Believers believe and skeptics doubt, and there's nothing little ole me can do about that. Yes, caps are a holy war.

You are very perceptive. Once you allow the idea that micro-effects, especially ones that by their nature *can't* be measured (as the hifi tweekos like to say) except by expert and gifted human listeners, the trail of things that can affect the results starts to build. I've seen audio nuts insist that they can hear the difference in identical circuits built on teflon circuit boards versus glass-epoxy. And that they could hear the difference between two copper wires, one of which contained a tiny percentage more oxygen than the other. Yes, it gets absurd.

I got crap to do and a life to live and certainly not enough time or resources to do a proper scientific test or deal with people's faith in the mighty high-end cap. I just wanted to post my subjective, anecdotal results for everyone to see. I am starting to wonder why, though, see previous paragraph.

At the bottom of this is the fact that we tinker with things to make them sound better to us. There can really be no disagreement that if something sounds better to you, it sounds better - to you. Good sound happens in the human brain, not in the ears. Just like beauty is in the eye of the beholder. Your anecdotal results are worth as much as anyone else's. Exactly the same, in fact.

This is why I work in software development. ... Oh, there are still holy wars (coding style, development methodology, language, platform), but I guess I have the good sense to stay out of them.

That is good sense. I ran a kernel development group for a while, and the religious wars are as vicious there as anywhere.

What's scary about religious wars is that you cannot win a religious war with true believers. You can only eliminate the true believers on the other side. This bothers me a lot, and not just for musical appreciation reasons.

[hasserl]

I may have mentioned Clever Hans the horse; I think I did. The problem with any internal bias is that you can't compensate for it even if you know it's there. Every aspect of a taste test matters to the opinion of the person testing; paying for caps, putting them in yourself, time since the last test, color of the cap, every thing. Having read some of the reasoning behind the way psychological testing is done, I tend to err on the side of thinking that a fair test by one person is almost impossible, and not because the person is uneducated, biased, or malicious. Instead, it's because they're human.

People get offended when you try to explain this to them, as if you're questioning their ears, their ability to hear, their honesty, etc. They don't get that this is not a matter of those things, but a matter of subconcious reaction to stimulus that cannot be conciously controlled. It effects everyone, I am not impervious to this, nor is anyone else. The only way to objectively evaluate things is to eliminate the subjective. If you don't do that then all you have is an interesting (or not so interesting) anecdote. To make concrete assesments from subjective anecdotes is ludicrous. But that is not to deny personal likes and dislikes, of which we all have many.

[Prairie Dawg]

People get offended when you try to explain this to them, as if you're questioning their ears, their ability to hear, their honesty, etc. They don't get that this is not a matter of those things, but a matter of subconcious reaction to stimulus that cannot be conciously controlled. It effects everyone, I am not impervious to this, nor is anyone else. The only way to objectively evaluate things is to eliminate the subjective. If you don't do that then all you have is an interesting (or not so interesting) anecdote. To make concrete assesments from subjective anecdotes is ludicrous. But that is not to deny personal likes and dislikes, of which we all have many.

Edwin Armstrong, the electronics genius, often observed: "It ain't what people know that's dangerous-it's what they know that ain't so."

[cminor9]

I may have mentioned Clever Hans the horse; I think I did.

Nice! I had never heard of that, I'll have to admit. Interesting discussion about more than just caps here. /. used to be this good.

[bsco]

Not only is the emperor naked, but he teabagged you while you were asleep, before riding off into the sunset on Clever Hans. Or maybe it was the head of marketing at Solen who did that, I don't know.

There's no such thing as "somewhat scientific", an experiment is either scientific or it's not. If you're not prepared to go the whole way and do a double blind test, you might as well take Frank Zappa's advice: "Shut up and play yer guitar"

I've joked (?) before about forming the "3dB club", of die-hard objectivists who refuse to consider any changes to their equipment that make less than 3dB of a difference to some measurable quantity.

RG: Here's a picture from an electronics forum I hang out on, that might make you smile.

Steve...I noticed that in the pic, the larger outside can is rated for 6800uf...the cap that is inside is a mere 2200uf.....somebody is getting taken for a money ride here.....

[Leo_Gnardo]

Steve...I noticed that in the pic, the larger outside can is rated for 6800uf...the cap that is inside is a mere 2200uf.....somebody is getting taken for a money ride here.....

Steve's been on a self imposed holiday from MEF a couple years now, paying attention to more important stuff like his career. In any case the photo's an example of what you get when you buy bargain basement deals from east Asia. Similar with semiconductors. If a deal is too good to be true, it likely is.

[Tom Phillips]

Steve...I noticed that in the pic, the larger outside can is rated for 6800uf...the cap that is inside is a mere 2200uf.....somebody is getting taken for a money ride here.....

And also the real voltage rating is 35V Vs. the 50V printed on the outside. Let's call that outside part the explosion shield.

[bsco]

And also the real voltage rating is 35V Vs. the 50V printed on the outside. Let's call that outside part the explosion shield.

Never noticed the difference in the voltage ratings...Kind of hard to make out the voltage rating on the bigger can....to me, it is an awful lot of trouble to go through to take a cap apart, change the guts out and seal it up again.....(didn't realize Steve was on extended vacation).......

[Gingertube]

Power Supply Caps - On a 6v6 PP HiFi Amp I found that 60uF/900V Polypropylene "Pulse Grade" sounded much more "relaxed" and powerfull than 100uF/450V Electrolytics. Of-course it was 4 times the size.
If using Motor Caps make sure you use Motor RUN caps and NOT Motor START caps. The Motor Start Caps are rated for intermittent use ONLY.
Haven't tried them in a Git Amp but would not be surprised to find similar improvements to what I found in the HiFi Amp.

Coupling Caps - the caps exhibit their worst distortion as the voltage across the cap reverses, mechanical stress from electric fields try to compress the dielectric between plates and there is some mechanical hysteresis. It is this hysteresis when the voltage across the cap reverses polarity which cuases the most objectionable "warts".
In most tube amps the coupling cap is a DC blocker and the absolute polarity of the voltage across the cap (DC + AC signal) never reverses and so you don't get that distortion mechanism, you really don't notice any difference between a 50 cent polyester or a 50 dollar piece of audio jewellry. Polypropylene are only a few cents more than polyester so I always use them.
This bit about coupling caps I noticed particularly in a SS HiFi preamp. The input cap had no DC voltage across it so the really expensive tin foil caps were quite a lot better.
But after redesigning the input such that there was always a DC level across the cap and the voltage never reversed when the AC signal was applied I found that a $2 polyproylene was as good as the $50 audiophool item.

So for GIT or HIFI Tube Amps where the voltage polarity across the cap never reverses, then cap choice is not that critical. You probably won't notice the difference between Poyester and polypropylene and the really expensive audiophool stuff is just a waste of money.

Cheers,
Ian

[mort]

lol @ "audio jewelry"

[Leo_Gnardo]

t is an awful lot of trouble to go through to take a cap apart, change the guts out and seal it up again.....(didn't realize Steve was on extended vacation).......

I don't think the counterfeiters go to that much trouble. They just accumulate a barrel full of pulls from wherever they can get 'em, package them in good looking cylinders (blast shields, yes Tom, heh heh... quite right!) slap a plastic cover on then flog 'em to whoever will buy on ebay.

Steve, as I'm sure you can tell, was a prize member here. Came a time he had to concentrate on his job. Of course it would be terrific to have him stop in just to say hello.

[tedmich]

If using Motor Caps make sure you use Motor RUN caps and NOT Motor START caps. The Motor Start Caps are rated for intermittent use ONLY

Cheers,
Ian

Often they don't know what they are selling, see here
LOT OF 50 MOTOR START CAPACITORS CBB60 SH 20uF 240VAC | eBay
those are 20uF PP film motor run caps, probably good to 500VDC for $0.8 each, and they've sold over 2,000 of them...

And the motorheads might like to use Italian made Ducati brand caps!
NEW DUCATI CAPACITOR 10uF 16.17.13EB EN 60252 | eBay