Paper in oil caps

[amptramp]

If you are talking about testing capacitors for distortion, there is a simple test for dielectric absorption:

1. Charge a capacitor to a fixed voltage value.
2. Short out the capacitor.
3. Remove the short.
4. Measure capacitor voltage.

This test can be done at uninstrumented measurement speeds.  You can do it with a battery, a piece of wire and a voltmeter.

What happens intenally is that the dielectric material is polarized so its molecules line up in the direction of the applied field.  When it is shorted, the voltage disappears, but there is no mechanism to restore the dielectric molecules to a random position and they naturally tend to stay oriented positive to negative.  When the short is lifted and the voltage is measured, you get the effect of polarized molecules lined up.  This is an effect similar to an electret, the permanent electrostat device that corresponds to a permanent magnet.  Electrets are commonly used in microphones and capacitors that use similar dielectrics may be microphonic.

I am not aware of any other distortion mechanism which is as important.  Obviously, if dielectric molecules line up under an applied field, the capacitance will be larger because of the proximity of the positive side of one molecule with the negative side of another.  This may explain why some capacitors sound good if they are coupling a plate to a grid with a consistent high voltage between them, but may add distortion at an input or a tone control stage where there is little DC bias across the terminals.  With a liquid dielectric like paper in oil, the randomizing effect of fluid flow may trump the electrostatic effect as long as the temperature of the capacitor is high enough. 

[induction]

If we suppose that he is personally crusading against the idea of caps making a sonic difference, because he cannot hear difference himself, we could conclude that he is tone deaf and committing an argument from incredulity.

That's not what 'tone deaf' means. This part of your argument would be classified as an appeal to ridicule.

there is evidence that cap material and even the voltage rating has an effect on the way it modifies the signal.

Empirical signal analysis tests are not very convincing to me.  The question isn't whether differences exist, it's whether they are audible.  The only way to examine this is tightly controlled double-blind listening tests.  If you can find someone who can consistently tell which cap is which in such tests, you prove your academic point that the differences are, in principle, detectable.

Then you move on to the real-world scenario: are the differences audible in a musical context?  Another set of double-blind listening/playing tests. 

How many caps in the signal chain does it take to tell the difference?  More tests. If you test enough people and enough scenarios, you'll end up with a distribution of cap detection abilities of the given population. People on the upper end of the spectrum (assuming anyone passes the tests) get to spend more money on components.

I suspect that the differences, if they exist, are so small that they are overwhelmed in influence by the rest of the signal chain/air temperature/humidity/etc, and that the first experiment will make the rest unnecessary.  But I haven't actually done the controlled experiments, so I could be wrong.

The likelihood that anyone in the audience cares is certainly much lower.  Whether or not that's important is more of a personal thing.

[FiveseveN]

http://www.scribd.com/doc/2610442/Capacitor-Sound

Yes, that's exactly what I said: distortion can be measured. But...

The question isn't whether differences exist, it's whether they are audible.

Bingo! Everyone can see that even in the worst-performing example in the article, the highest-amplitude distortion product is 65 dB down, right? So it's not Scribd messing with me or my apparent overwhelming bias against the golden-eared. Yes, some people claim to be able to hear 100 ppm of distortion. Some people claim to have been kidnapped by aliens. Want to guess which group is more numerous?

My skepticism on the matter is rooted in our growing knowledge about the immense gap between what we percieve and what we imagine, what our brain assumes in order to save resources.

[Bill Mountain]

I'm not a cap apologist but there is something special about big fat orange drops in a Fender-ish amp.

Why not put some big "mojo" components in a pedal if it makes you feel good?

[FiveseveN]

Hey, that's a completely different story. I've hoarded a bunch of "mojo" parts myself, because, you know, they're quirky and pretty.
If it makes you or your customers feel better, I say go right ahead, as long as you're not disingenuous.

[wavley]

I'm not a cap apologist but there is something special about big fat orange drops in a Fender-ish amp.

Why not put some big "mojo" components in a pedal if it makes you feel good?

I can't tell you how many silverface fenders I've pulled the poo brown caps out and replaced with orange drops for a remarkable improvement.  To paraphrase Morrissey "Some caps are better than others, yes some caps are better than others.  Some cap's mothers are better than other cap's mothers"  The poo brown caps have always sounded worse, so it's not a new cap vs. old cap thing. It lifts the final veil off of the upper mid range in my audiophool voice  But seriously, it does make a difference.  I just fixed a friend's 62 Vibrolux which is pretty magic.  I had it and my somewhere around 69 or 70 dead stock one sitting right next to it and slowly in stages I brownfaced mine.  I started with supply caps, tested, coupling caps, tested (it made a great but not earth shattering difference), and then started making all the circuit changes one by one and testing.  I haven't gotten to the trem mod yet because I have to order  a pot, but I have certainly gotten it close enough that I consider my amp (which I thought was decent sounding before) to be pretty magic.  Was it scientific?  Not exactly, but I did take pretty good care to understand everything that was changing.

There is a point where mojo gets out of hand and I really would like to see some science to back it up though.  I don't really begrudge somebody some mojo unless it turns into some real cork sniffing elitism and blanket statements, because so often it's about application.  Isn't it R.G. that proved if you used old brown resistors over 100 volts that it actually does create desirable harmonic content, although it may be negligible?  So 9 volts=noise 150 volts=magic?  Is this true of caps too?

Particularly in a dirt box I have my doubts about the extra fidelity of a certain kinds of caps running at low voltage, although I don't care for regular disc ceramics in just about anything, but anything other than orange discs might just be mojo when it comes to low voltage dirt.

If the mojo makes you feel better, then cool, it's your rig.  Let's just realize that sometimes it's just mojo and don't rationalize it so much.

[Bill Mountain]

I'm not a cap apologist but there is something special about big fat orange drops in a Fender-ish amp.

Why not put some big "mojo" components in a pedal if it makes you feel good?

I can't tell you how many silverface fenders I've pulled the poo brown caps out and replaced with orange drops for a remarkable improvement.  To paraphrase Morrissey "Some caps are better than others, yes some caps are better than others.  Some cap's mothers are better than other cap's mothers"  The poo brown caps have always sounded worse, so it's not a new cap vs. old cap thing. It lifts the final veil off of the upper mid range in my audiophool voice  But seriously, it does make a difference.  I just fixed a friend's 62 Vibrolux which is pretty magic.  I had it and my somewhere around 69 or 70 dead stock one sitting right next to it and slowly in stages I brownfaced mine.  I started with supply caps, tested, coupling caps, tested (it made a great but not earth shattering difference), and then started making all the circuit changes one by one and testing.  I haven't gotten to the trem mod yet because I have to order  a pot, but I have certainly gotten it close enough that I consider my amp (which I thought was decent sounding before) to be pretty magic.  Was it scientific?  Not exactly, but I did take pretty good care to understand everything that was changing.

There is a point where mojo gets out of hand and I really would like to see some science to back it up though.  I don't really begrudge somebody some mojo unless it turns into some real cork sniffing elitism and blanket statements, because so often it's about application.  Isn't it R.G. that proved if you used old brown resistors over 100 volts that it actually does create desirable harmonic content, although it may be negligible?  So 9 volts=noise 150 volts=magic?  Is this true of caps too?

Particularly in a dirt box I have my doubts about the extra fidelity of a certain kinds of caps running at low voltage, although I don't care for regular disc ceramics in just about anything, but anything other than orange discs might just be mojo when it comes to low voltage dirt.

If the mojo makes you feel better, then cool, it's your rig.  Let's just realize that sometimes it's just mojo and don't rationalize it so much.

I agree with everything you've said.  I don't have a rational reason for disliking the ceramics that I use for breadboarding (but never build with).  But how can we claim that science proves one type of part is not better than others but then say this part is better than this part.  What would you or anyone say to someone who said brown caps in a Fender sound just as good???

I hate mojo (and most ad copy for that matter) but the attitude we have about proving without a shadow of a doubt why something should be done as certain way is the reason why some people get driven off of this board.  It's also the reason I'm afraid to show all of my experiments because I know I can't back up why I did something a certain way and why it's better than other ways of doing it.  None of this is against you personally.  Your post just provided me a segue to get some things off of my chest.

As the internet matures I see more and more scientific pissing contests on almost all the forums I visit.

[R.G.]

You want *good* caps?

Go to a welding supply store and buy some of the 2" x 4?" glass plates used for the front of a welder's helmet. Then to the metal-foil supply store for some tin (not aluminum) foil, thin as you can get it.

Supplies in hand, begin stacking. Lay down a plate of glass. Then a rectangle of foil, with 1/8" to 1/4" spacing on three edges of the glass, and lapping outside the glass on the fourth side. Then a plate of glass, and another foil, but this time the section outside the glass is on the opposite side of the stack from the foil just below it. Repeat. Do as many layers as you want capacitance. The capacitance is pretty easily calculable from junior-physics parallel plate equations. When you have enough, solder the foils on each side (hence the tin, not aluminum) of the stack. Put on a top glass for passivation, bind the stack and passivate/glue it with something like varnish or epoxy on all sides.

This makes a very, very high quality, linear capacitor with quite a high voltage rating.

It's just big, heavy, and fragile. 

[bluebunny]

^^^ Let's see Jon Patton squeeze *that* into one of his 1590A builds! 

[wavley]

First of all, let me say that my use of the word magic to describe amps was meant to describe how great they sound.  After sitting down with two amps, two schematics, comparing, and changing components and circuits one by one in order to analyze that part of the circuit's contribution to the sound.  Yeah, it sounds magic now, but I absolutely know how I got there.  Of course it wasn't perfectly controlled, I wasn't going to sit down and record a riff and then play it back so that the nuances of my playing didn't influence the sound or anything, it's pretty absurd to do that just for myself.  I took an amp that sounded pretty blah and made it sound great, while comparing it to a known great sounding amp.

Second, please nobody take it as an attack on any of them.  Honestly, I dig mojo components (although I personally refrain from calling them that) if I have them around and I feel they'll do a good job in the circuit, or I just want it to look cool just for me.  I don't dig disc caps because on a bunch of occasions I've found them to be little microphones, I prefer not to invite that into my circuits because after all in the quantities in which I build the cost for a component that I know isn't going to be a little microphone is worth it to me.

I will on occasion ask for some sort of science to back something up that makes me roll my eyes, and sometimes that science backs up what the person was saying and it's great, you've convinced me.

What would I say to someone that like the sound of brown caps in a Fender?  Well, what folks think sound good is totally subjective for one, I like 13-56 flatwound strings on a Jaguar, not really what a lot of other folks consider great tone.  So it really depends on how condescending they were when they said it as to what my response would be.  BUT, in MY experience, and all of the techs I used to work with at the shop, poo brown caps sound worse than the older blue ones or orange drops, but honestly the real night and day differences between the brown, black, and silver fenders are the circuits... there is a pretty big difference in sound between using the 12ax7 phase inverter of a brown fender and the 12at7 of the black and silver.  They have different PI values, different tone stacks, and different negative feedback and when you combine all of those things it made the amp sound magic to my ears.  When I was a kid I and rode BMX I had a friend that was always concerned with shaving an ounce or two off his bike here and there, when I asked him why he said "One ounce here, two ounces there, pretty soon you get up to a pound or two.  A pound or two can be the difference between winning and loosing the race."  So yes, I will take the caps I think sound a little better as part of the equation

And Bill, I actually thought I was backing your last post up up, I didn't mean to offend you and I'm not the most eloquent person so it may be my fault. The fact that I work in radio astronomy R&D, I tend to be required to back my findings up with science at work the IEEE fellow I work for tends to like that kind of stuff so sometimes the skeptic in me wants to see some science.  At home... not so much, but I still tend to use the same methods.  I'm no RG or PRR, and wouldn't pretend to be, I'm certainly not going to attack anybody for not completely understanding a circuit, if it sounds good then it sounds good... awesome.

[Bill Mountain]

And Bill, I actually thought I was backing your last post up up, I didn't mean to offend you

You were backing me up and you didn't offend me.

I should not have quoted you.  It was just some stream of conscience typing.

I enjoyed your post very much.  It just made me evaluate myself.  I crave the scientific backing for my reasoning but I also have a soft spot for certain types of components.  I was just trying to point out that I find it difficult to judge anyone when I'm not in control of my own feelings.  I was trying to have an open discourse so I provided an alternate viewpoint.

No one should feel the need to defend themselves to me.  For that I am sorry.

[wavley]

And Bill, I actually thought I was backing your last post up up, I didn't mean to offend you

You were backing me up and you didn't offend me.

I should not have quoted you.  It was just some stream of conscience typing.

I enjoyed your post very much.  It just made me evaluate myself.  I crave the scientific backing for my reasoning but I also have a soft spot for certain types of components.  I was just trying to point out that I find it difficult to judge anyone when I'm not in control of my own feelings.  I was trying to have an open discourse so I provided an alternate viewpoint.

No one should feel the need to defend themselves to me.  For that I am sorry.

It's cool, I like me some spirited discourse about electronics.

Honestly, most of my emotional response was to R.G.'s new signature "Magic: any technology you do not understand", which I felt was a dig on why I felt my amp sounded like magic and that I didn't understand how it got there.  Which it may or may not have actually been, so I probably shouldn't get emotional so quick.  So here's a preemptive "Sorry R.G."

[edit] RG, I realize that you may have taken offense to the example of the resistors.  I was trying to make a point that sometimes there is science to back up "mojo" in certain applications, but the mojo doesn't work in the wrong application.

[defaced]

R.G.

Magic: any technology you do not understand

I just noticed this.  I just finished a project where I had to take pre weld and post weld distortion evaluations of the test I was welding.  I set up two tables, before and after, on the same sheet of paper and separated them by a big white area with text in the middle that reads "Magic Happens".  I know no one will ever ask for that piece of paper, but if anyone ever reads it besides me, I hope they see the humor in it. 

Humor aside, I'm on a quest for the least expensive, legitimately sourced (no eBay BS) coupling caps I can find.  Currently Epcos are winning out with the B32529 series caps (which Mouser stocks many values of, thankfully).  In a very unscientific way I am going to see if I notice any deleterious effects of these vs the 225P Sprague caps I use now (literally the least and most expensive 400v 0.022u cap stocked on Mouser right now, $1.43 vs $0.18). 

[wavley]

R.G.

Magic: any technology you do not understand

I just noticed this.  I just finished a project where I had to take pre weld and post weld distortion evaluations of the test I was welding.  I set up two tables, before and after, on the same sheet of paper and separated them by a big white area with text in the middle that reads "Magic Happens".  I know no one will ever ask for that piece of paper, but if anyone ever reads it besides me, I hope they see the humor in it. 

Humor aside, I'm on a quest for the least expensive, legitimately sourced (no eBay BS) coupling caps I can find.  Currently Epcos are winning out with the B32529 series caps (which Mouser stocks many values of, thankfully).  In a very unscientific way I am going to see if I notice any deleterious effects of these vs the 225P Sprague caps I use now (literally the least and most expensive 400v 0.022u cap stocked on Mouser right now, $1.43 vs $0.18). 

Cap technology has come so far in the last 20 or so years that I bet the difference between a "good" cap and a "bad" cap today is much less than those of yesteryear.

[tubegeek]

"And all this science, I don't understand
It's just my job five days a week
A rocket man, a rocket man

And I think it's gonna be a long, long time 'til touchdown brings me round again to find I'm not the man they think I am at home
Oh no, no, no, I'm a rocket man
Rocket man, burning out his fuse up here alone."

-Bernie Taupin

[wavley]

You want *good* caps?

Go to a welding supply store and buy some of the 2" x 4?" glass plates used for the front of a welder's helmet. Then to the metal-foil supply store for some tin (not aluminum) foil, thin as you can get it.

Supplies in hand, begin stacking. Lay down a plate of glass. Then a rectangle of foil, with 1/8" to 1/4" spacing on three edges of the glass, and lapping outside the glass on the fourth side. Then a plate of glass, and another foil, but this time the section outside the glass is on the opposite side of the stack from the foil just below it. Repeat. Do as many layers as you want capacitance. The capacitance is pretty easily calculable from junior-physics parallel plate equations. When you have enough, solder the foils on each side (hence the tin, not aluminum) of the stack. Put on a top glass for passivation, bind the stack and passivate/glue it with something like varnish or epoxy on all sides.

This makes a very, very high quality, linear capacitor with quite a high voltage rating.

It's just big, heavy, and fragile. 

You mean a little like this?


When we need a "good" coupling cap in the femtofarads for GHz work we use custom made parallel plate caps, of course we use quartz instead of glass and the plates have bondable gold.  These particular ones are 25x6x3 mils.

Excuse the blurry pic through a microscope using my cell camera.

[R.G.]

Honestly, most of my emotional response was to R.G.'s new signature "Magic: any technology you do not understand", which I felt was a dig on why I felt my amp sounded like magic and that I didn't understand how it got there.  Which it may or may not have actually been, so I probably shouldn't get emotional so quick.  So here's a preemptive "Sorry R.G."

[edit] RG, I realize that you may have taken offense to the example of the resistors.  I was trying to make a point that sometimes there is science to back up "mojo" in certain applications, but the mojo doesn't work in the wrong application.

No apology necessary. I'm mildly amazed at this. I was not following this thread to any significant extent. I had not read your comment about your amp sounding like magic. And yes, I can see where you might have a response to that, justifiably so if I was being snippy.

So, I'm sorry for the unintended slight - it really was an accidental confluence. I knew nothing your post at the time I put that up. 

The quip had its roots in the saying that "Any sufficiently advanced technology is indistinguishable from magic." and the derivative "Any technology distinguishable from magic is insufficiently advanced."

I was profoundly affected by reading the question about what would happen if a true scientific genius from the 1800s was examining and trying to understand and operate a nuclear power reactor. The technology base to avoid a disaster is simply not there - and he would have undoubtedly have believed that the reactor was indistinguishable from magic.

[davent]

You'll need something bigger then an "A" for a few of these PIO's. http://www.partsconnexion.com/DUELUND-74523.html

[induction]

You'll need something bigger then an "A" for a few of these PIO's. http://www.partsconnexion.com/DUELUND-74523.html

And maybe a mortgage.

[Bill Mountain]

You'll need something bigger then an "A" for a few of these PIO's. http://www.partsconnexion.com/DUELUND-74523.html

I like how the MSRP and the sale price are the same.