Capacitors.. which ones for which applications?

[tubeswell]

Originally Posted by Tele-Cat

If you like the brown turds, that's all that matters.

yep I used them in my 5G9 (and cheap 0.6W metal film resistors throughout) and it sounds pretty damn amazing.

(Having said that I used mustard caps and CC resistors in a 5E3 and that sounds pretty damn amazing too, but of course in a completely different way)

[Steve Conner]

Come off it guys, they all sound the same (except maybe disc ceramics) You won't hear the difference in a properly controlled test.

If it makes you feel good to have some boutique capacitors in your amp instead of cheap mylar greenies, and that good feeling makes you play guitar better, go for it. But I think that's the only effect there'll ever be.

I wouldn't like to think that people are reading this thread and feeling inferior because their amp has "brown turds" instead of whatever brand of capacitor is cool just now. Again, all capacitors that aren't actually the wrong value or leaky will sound the same, and I challenge anyone to disprove this.

I'd make up an ABX test with 24-bit FLAC files for you to try online, but you'd just claim that the crappy capacitors in my digital equipment were "masking" the differences.

[Tele-Cat]

I like the name "brown turds." Heh heh heh.

[melvin]

Think there's anything to this?

The "Sound" of Capacitors

[gbono]

Yes Mr Steve appears to be looking at and measuring the dielectric apsorption properties of various dielectrics. Non-linear yes, but so is the transfer function of a bipolar transistor - what have we learned? I'm with Doug Self (and others) you ear isn't designed to hear the effects of these "non-linearities".

I can't wait to look at data for the audible effects of lead free solder (does SAC305 sound better than SAC105)???

[tubeswell]

What I meant by amazing and in a different way is that I think my amps sound amazing and they are all different.

Mojo schmojo. The article about caps is interesting but the differences probably aren't ones that you can hear in a geetar amp, (except for disc ceramics used as hi freq caps - they are a bit more bright/brassy than other types to my ear. Well that's what I hear from trialing them anyhow. Individual ears and brains are unique to a certain extent, and some people may hear a difference where others don't, just like noticing different flowers in the garden. How much of a difference? enough to notice some change in timbre/texture, but its not like one is red and the other is blue kind of different)

[Dave H]

I think capacitor type is very important in guitar amps.

I’ll only use the capacitor types that happen to be in the free issue bins at work on the day I need them.

Dave H.

[hasserl]

Again, all capacitors that aren't actually the wrong value or leaky will sound the same, and I challenge anyone to disprove this.

I'd love to see this too. I'd love to see someone actually identify which caps were which in a blind test. Build a test amp, put coupling caps of identical capacitance value but of different construction type on switches so they can be quickly switched in/out of the circuit, and then conduct a blind listening test, and identify the good / bad caps. I have my doubts that anyone could do it. It would certainly be interesting in any case.

[RudeBoy]

Originally Posted by gbono

Note that the melting point of polypropylene (capacitors) is 160 C. I believe polystyrene is over 260 C. Not that hard to damage these while soldering them into the application.<snip>

From American Capacitor Corporation, some temp data:

Polystyrene -55C to +85C
Polypropylene -55C to +105C
Polyester (Mylar) -55C to +125C
Polycarb -55C to +125C
Teflon -55C to +250C

Some details on dielectrics here.

I like polystyrene, but I'm a bit concerned about the low temp range. I'd use them, located away from a heat source. I tend toward the foil wrap with epoxy endfills. Mallory 150s may be those - haven't checked yet.

[Enzo]

Well, I don;t think you need to be overly concerned. 85 degrees C is about 185 degrees F.

[Steve Conner]

Yep, they're all considerably more rugged than, say, germanium transistors. Most RF coax cable has a polystyrene dielectric and is difficult to solder, because if you're not quick the dielectric melts and the core shorts against the screen. But that doesn't seem to be a problem when soldering capacitors.

Some amps I've seen used polystyrene film/foil caps in the tone stack positions where Fender would have used disc ceramics. These caps don't have any outer casing and look like tiny Swiss rolls.

Electrically they're probably no different to a silver mica cap, although they have more self-inductance that makes them a bit useless for RF. I prefer them to silver mica or ceramic for my own amp building, though I'm not exactly sure why

[tubeswell]

Originally Posted by Steve Conner

These caps don't have any outer casing and look like tiny Swiss rolls.

I prefer them to silver mica or ceramic for my own amp building, though I'm not exactly sure why

Hmmm... when you build these amps, you're not going without enough to eat are you?

[Tele-Cat]

Originally Posted by Steve Conner

Yep, they're all considerably more rugged than, say, germanium transistors. Most RF coax cable has a polystyrene dielectric and is difficult to solder, because if you're not quick the dielectric melts and the core shorts against the screen. But that doesn't seem to be a problem when soldering capacitors.

Some amps I've seen used polystyrene film/foil caps in the tone stack positions where Fender would have used disc ceramics. These caps don't have any outer casing and look like tiny Swiss rolls.

Electrically they're probably no different to a silver mica cap, although they have more self-inductance that makes them a bit useless for RF. I prefer them to silver mica or ceramic for my own amp building, though I'm not exactly sure why

I always use an alligator clip attached to the lead of any cap I'm soldering - acts as a heat sink. I've burned my fingers a few times taking the clips off the leads but a lot of heat was kept away from the cap by doing that.

[Jazz P Bass]

Just thought I'd add my two cents to the tone debate.
The key word in my mind is the tolerance of the capacitor.
Plus or minus 20-30% is huge when talking small value caps.
Is the actual change in capacitance what people hear as a change?

[Steve Conner]

Quite possibly, yes. Earlier I mentioned a properly controlled test, and one of the controls would be to check that all of the capacitors under test were very nearly the same capacitance. If the tolerances were wide enough to make more than about 0.5dB difference to the tone, I'd select them.

But to be pedantic, 20-30% tolerance isn't any worse for a small value cap than a large one. It's still 20-30% of the capacitor's value, no matter what the value is.

[rockon1]

Just jumping in here trying to learn. Great stuff! So it would be OK to swap an .0022 400v poly with a ceramic disc type of the same value? They seem so small in comparision. bob

[guitician]

Caps all have their particular applications, that's why their are so many types. I realize that the "Sound" of the cap is very subjective too. But in any application, physical aspects, that are not part of the capacitors specs, will still come into play and change your outcome.

[Enzo]

A .0022 400v of any type will work is a circuit calling for such a part. You may or may not hear some subtle difference, but the circuit will work fine.

[rockon1]

Originally Posted by Enzo

A .0022 400v of any type will work is a circuit calling for such a part. You may or may not hear some subtle difference, but the circuit will work fine.

Thanks . Just seemed odd they would use such a big cap when a smaller one would do. Bob

[Rhodesplyr]

Originally Posted by Steve Conner

I do believe that you should avoid ceramic caps in an audio signal path, though. They can be non-linear (capacitance changes with voltage) and microphonic.

I've often read this, but I think it needs a little refinement because there are so many different types of ceramic capacitors.

Pure ceramic capacitors, NP0 / C0G types, are actually very good. I've seen distortion tests on them that found them only slightly inferior to polystyrene. They are also very stable and heat-tolerant. The downside to these is that they are only available in small values, often no more than a few hundred picofarads, due to size.

To get more capacitance in a smaller package, the ceramic is doped with various compounds to increase its dielectric constant. This is the case with Z5U and X7R types you find in some audio equipment. These are the "bad" ceramic capacitors that have given all ceramics a bad reputation. They can change value with temperature, applied voltage, and age, and they can be piezoelectric or microphonic. They are essentially cheap substitutes for film caps in audio signal paths.

I've replaced some Z5U types with mica or film capacitors with very positive results, especially the REALLY tiny ones that started appearing in the 1980s. If older discs are C0G or NP0 (or NP750, NP1500), I leave them alone.

Don't tar all ceramics with the same brush, especially below 100pF :-)

[Enzo]

You may have a point being fair to ceramic caps, but when the cap in question is a .01, your fave NPOs don;t make it onto the playing field, and by elimination making all the remaining ceramic candidates "bad."

[Steve Conner]

That's a good point though, are the ceramic discs originally used in Fenders the "good" type or the "bad" type?

The Z5U and X7R types usually have a lower working voltage, as far as I know, so might not even be usable in a tube circuit.

[Enzo]

Dunno. I just used my incredible troubleshooting powers to decide if the capacitance range of the "good" type don;t go high enough, then they must have to be the "bad" ones.


Didn;t think any farther than that.

[Gollum]

I'm not going to pretend that I truly KNOW anything here, as I'm relatively new to the electronics game as well. I've been toying with a soldering iron for a decade now, since I was a wee kid, but that makes me no expert.

But, to play devil's advocate here I'm going to mention something I read in "The Guitar Amp Handbook" by Dave Hunter. He interviewed many of the "greats" when it comes to guitar amp building, one of which being the late Ken Fisher. This interview with Ken was great and I found it very enlightening. It was interesting to hear one of the biggest amp gurus that's walked this earth to talk about the difference between all these different parts, but to sum most of it up that you can make the amp sound good dispite what you use.

Unfortuantely he didn't talk much about capacitors, but I'm betting his statements should give a clue to the fact that design tolerences can be made up for. If two caps of truly the same value sounded different, you could probably make up for it elsewhere if it was a problem.

The only design aspect that Ken speaks specifically about is resistors, in which he always prefers carbon film over metal film.

He even goes on to talk about how overhyped transformers are.

But also remember that this same man will talks about the flow of electronics in extruded metal and how wire is directional, and he made sure his amps were wired directionally correct, since wire conducts better one direction than the other........

Some other food for thought is that many of the interviews in this book are contradictory, that is to say that even the great amp builders out there don't agree, or at least go about the same goal in vastly different ways. A Dr Z isn't made like a dumble, and a dumble isn't made like a matchless, but they all sound good in their own right.

Oh, another point to be made is that Ken Fisher sold his amps for less than nothing compared to their market value, even long before he died. He didn't make them for huge profit, and didn't put the most expensive parts into them. He was able to make amps to sell between $1,000-2,000 hand wiring them in the USA. There's no way he was using top shelf parts, so obviously you don't need to spend a ton of money to get amazing tone.

[Tele-Cat]

On the other hand, I've spoken to Skip Simmons who says caps and transformers are uber-important.

Opinions are like...well, you know.

[kepeb]

i think the test mentioned earlier would be pretty interesting (changing out caps of the same rating/value in a blind test)

i was confused at first when i was doing little guitar pedal circuits, there were, as some of you have said already, lots of opinions and statements which were misleading and seemed to have no real basis for the claims.
i just used what i had, and have come to the conclusion that the cheapest is usually what goes in with many manufacturers.

i have often also questioned the tests and comparisons i listen to online.
i think they very rarely give an accurate example of whats going on with the sound because they all have far too many unaccounted variables.

if anyone does ever get round to doing a test like this i think you should have all of that removed to make it fair.

one of the main points people seem to miss is the performance aspect.
the signal should be a re-amped unaffected guitar with the speaker/cab, mic and all the settings untouched inbetween.
i have seen and heard many rave reviews based on 5 second youtube clips of amps pedals, guitars etc.
you need a fair comparison.

the cap one would be very interesting tho.

who's volunteering?

[Phostenix]

Rod Elliot's take on this can be found here:
Cables, Interconnects and Other Stuff - The Truth

[kepeb]

thats some good stuff. if only i could write like that
i'm gonna read the rest probably maybe clear up an issue i have over instrument cable capacitance too.

i still wouldn't even say there is a 'definitive' answer after reading that
i would definitely say those who are on the 'it makes a big difference' side are either:
capable of super hearing
already convinced mentally, and therefore believe what ever they want (or dont want )
or
are in marketing


there is still room for debate tho.
theres always last straw theory... so although the affect of one cap is practically immeasurable, or completely invisible to our standards. thats not to say that the combination of 50+ caps in one circuit wouldn't amount to a register-able difference in how we hear it.

regardless, the whole debate comes from a question about what the audible difference is at the end.
i think everyone can agree that some things sound better than others, whatever you use, somebody's gonna be there to tell you different.

but its also nice to think you have put the best available ingredients into whatever your making. if its better or not is ALWAYS opinion.

i like cheap stuff personally.
i also know electrolytic's have a shorter lifespan.
but those ones on ebay for guitar tone controls, that look like bumble bees are cool. without doubt!

think i'll just stay confused

[Enzo]

LAst straw?

Yes accumulated small differences can add up to a much larger one. However, over the course of an entire circuit, they tend to cancel out, unless oddly ALL of them lean to the same end of their scale.

COnsider that the old Fenders were made with 20% parts. 20% resistors were not uncommon in those days, though they did have the 10% and 5% readily available. But Leo Fender was into "good enough" and didn;t spend the extra money for more precision in the parts.

Of course a 100k resistor could measure from 80k to 120k and be within its specs. Electrolytics were worse. A common tolerance spec was -20/+80%. Seriously. Many Fender schematics say right on them, readings are for reference only and my vary by 20%. The net effect was one amp didn;t sound like the next, depending upon how all the tolerances added up. You could seriously have a discussion about how Joe's new Fender was a "better one" than Fred's new Fender.

[Steve Conner]

What Rod Elliot and Douglas Self said. If you still have any unanswered questions after reading their work on capacitor sound, then propose some experiments and we can see about getting them done. Here are some random thoughts:

1: Actually using live guitar playing in a test complicates things hugely, for two reasons. It varies between tests, and the guitarist is subject to experimenter expectancy. (If he knows his favourite capacitors are in the signal chain, he might play better.) Cancelling this expectancy effect would mean the extra hassle of a blind test, and we still have the random variations.

So the thing to do is put recorded music through a capacitor, or test amps with a 24-bit recording of DI'd electric guitar into the input. (Not sure if this is what a previous poster meant by re-amping.)

2: Micing up an amp is fraught with difficulty, too. If you even stand in a different place in the room, or don't quite close the door properly, it can affect the frequency response. Only by a tiny amount, but tiny differences are what we're looking for here. So another vote for just sticking canned music through a capacitor.

3: The S-shaped curves generated by ceramic caps in Steve Bench's experiment look like some pretty significant harmonic distortion that would very probably be audible in a test. At least as much mojo there as carbon comp resistors. If anyone wants to try an experiment, I suggest we do an ABX test between a silver mica and a ceramic to start.

4: Douglas Self argued that a capacitor can only affect tone in proportion to the AC voltage across it. He backed this up with distortion analysis experiments. A DC blocking capacitor theoretically doesn't have any AC voltage across it, except at very low frequencies. So DC blocking capacitors should not affect tone. However, bright caps, tone stack caps, presence circuit caps, all have significant signal voltage across them in the midrange and treble, that's their purpose. If I were doing tests with amps, I'd concentrate on these capacitors. Probably the bright caps and tone stack treble caps are the most important.

[kepeb]

Originally Posted by Enzo

COnsider that the old Fenders were made with 20% parts. 20% resistors were not uncommon in those days, though they did have the 10% and 5% readily available. But Leo Fender was into "good enough" and didn;t spend the extra money for more precision in the parts.

definitely. your right.
and with the possible drifting of any of those components since as well.
i think its too easy for me to go off topic with this one. but it seems that was the way with the guitars too, i know they are all still cherished and continually copied, replicated and reproduced. but the FACT is, they were jammed together with the least expensive parts and shipped out fast for maximum turnover.

its only possible to measure something to within the boundaries of our understanding or even equipment on a lesser scale.
but to the original question imho is
i think caps are chosen through efficiency/reliability vs. cost and lastly, personal choice.

it would be nice to have a reliable reference set of test results to base that 'choice' on tho. instead of just marketing and bad mojo.

also i was thinking specifically of guitar amps when i mentioned 're-amping' that was to avoid differences in playing, the exact same guitar part played from a digital source is the only way to measure accurately.
reamping is like the reverse of a DI tho. puts the impedence and signal level back to what the guitar preamp would expect from a signal.

[Gollum]

Originally Posted by Steve Conner

What Rod Elliot and Douglas Self said. If you still have any unanswered questions after reading their work on capacitor sound, then propose some experiments and we can see about getting them done. Here are some random thoughts:

1: Actually using live guitar playing in a test complicates things hugely, for two reasons. It varies between tests, and the guitarist is subject to experimenter expectancy. (If he knows his favourite capacitors are in the signal chain, he might play better.) Cancelling this expectancy effect would mean the extra hassle of a blind test, and we still have the random variations.

So the thing to do is put recorded music through a capacitor, or test amps with a 24-bit recording of DI'd electric guitar into the input. (Not sure if this is what a previous poster meant by re-amping.)

2: Micing up an amp is fraught with difficulty, too. If you even stand in a different place in the room, or don't quite close the door properly, it can affect the frequency response. Only by a tiny amount, but tiny differences are what we're looking for here. So another vote for just sticking canned music through a capacitor.

3: The S-shaped curves generated by ceramic caps in Steve Bench's experiment look like some pretty significant harmonic distortion that would very probably be audible in a test. At least as much mojo there as carbon comp resistors. If anyone wants to try an experiment, I suggest we do an ABX test between a silver mica and a ceramic to start.

4: Douglas Self argued that a capacitor can only affect tone in proportion to the AC voltage across it. He backed this up with distortion analysis experiments. A DC blocking capacitor theoretically doesn't have any AC voltage across it, except at very low frequencies. So DC blocking capacitors should not affect tone. However, bright caps, tone stack caps, presence circuit caps, all have significant signal voltage across them in the midrange and treble, that's their purpose. If I were doing tests with amps, I'd concentrate on these capacitors. Probably the bright caps and tone stack treble caps are the most important.

WORD!!! (again, I'm a self proclaimed newbie, so don't over analize my posts m'kay?)

I'd read that article previously and it truly made sense in my mind, though Rod Elliott is obviously focuse on Hi-Fi amplification, which can be apples to oranges sometimes for us guitarists. But it really made me wonder how much things like filter caps could truly make a difference, as long as it does it's job within spec of course...

It wouldn't be hard to rig up some ON/ON/ON switches to some various caps and see how different they sound. Personally I'd like the test subjects to actually be put through some tests to see how close to spec they are from the get go though.

I think personally though, I'll not worry too much about my caps, and focus more on buying the right type of resistors, which seem to have a more proven tonal difference.

[Howlin' Mad Mac]

Found this to be a very good thread folks. I've always had my own thoughts & ideas on this subject & found a lot of wisdom from some of the posts from people who seem to be more in the know & was glad to not see a lot of the usual posts like "if you don't use "xyz" you ain't got sh*t kinda stuff. As for my two cents from somewhat limited but educated experience use polys whenever possible/practical with a prefrence for a quality-made cap (which does not necessarilly mean the most expensive) as their values tend to be more consistent & don't deteriorate over time the way many of the older "more botique" types, especially beeswax & many paper foil & oil types tend to. Second use electolytics only where you have to due to cost or size & here is where you definitely don't want to "skimp" & use the cheapies. The longer life of the better electrolytics always pays in the long run needing to replace them much less often & less tube/transformer failure usually due to caps going bad. That said while "Sprague Atoms" are well made quality caps there are many other caps as well made yet much smaller in size with better temperature ratings & tolerances. Most newer types of Sprague, Illinois & Nichicon electrolytics are IMHO superior to Atoms though I will be the first to admit I can't hear any sonic difference myself though I won't judge those that say they can. When I use Atoms it's because who I'm doing the work for tends to prefer them or in my own builds to be more historically acurate or because using them will help sell the finished product. Now for the very tiny values I prefer silver mica types to ceramic discs as they tend to have tighter tolerances & in my opinion a nicer "look" though again I'll admit not because I find them to sound different. Now to go against everything I've just said... when it comes to coupling caps I've used both Orange Drops & Mallory 150's seeing little if any real sonic difference between them but I will sometimes use foil & oil caps here only because they sound more "round" or less "edgey" (how do you like those descriptive terms) or what I guess you would call "smoother". Again I've come across others that prefer the tone of a good poly cap here. If you decide you would like to try an old school foil & oil cap here, my recommendation would be to use the Mojo Vitamin Q caps only because they're a quality built cap selling for much, much less than any other foil & oil types I've come across & again personally can't hear any difference from other types selling for 2, 3, 4 or more times as much. In conclusion always use quality caps while keeping in mind sometimes (& more often than you might think) more expensive doesn't mean better... just more "snob" appeal. Please feel free to clarify/debate/argue any "valid" points you should care to offer but as stated these are only "my" opinions not etched in stone & handed down to me from the guitar amps gods on high so no need for "name calling" or "finger pointing". We all share a love & passion for great guitar tone & life's to short & precious to be nasty to others... & I promise to treat everyone else with the same respect. Peace.

[Alf]

I have always wondered if you have got a good quality cap then imho the most important thing next would be : how much phase shift does it have ?
Especially when used within the nfb loop. It can cancel out certain frequencies ?
Unfortunately I don't have the time to test this laboriously but maybe somebody already has.

Is there a way of knowing the degree of phaseshift a cap has ?

Please comment on this thought.

Alf

[Steve Conner]

Quick answer: 90 degrees. That's the whole point of capacitors, the (assumed sinusoidal) current through one leads the applied voltage across it by 90 degrees.

More carefully thought out answer: 90 minus the inverse tangent of the dissipation factor (see your capacitor datasheet) so 89.99999 or something. The dissipation factor is a measure of the capacitor's quality, the smaller it is the lower the ESR and dielectric losses, and the closer the capacitor is to an ideal capacitor.

Even more in-depth answer: 90 degrees applies to a capacitor tested on its own. Most capacitors are in circuits with resistors and inductors. The phase shift of a RC or RLC circuit is a well-known function of frequency that you can look up in any electronics text book or Wikipedia.

You would struggle to find a capacitor whose ESR and dielectric losses were anything but negligible, compared to the other impedances in tube audio circuits.