Ceramic capacitors. Re-thinking them.

[brett]

Hi.  I just got a pack of ceramic capacitors from that Chinese online marketer. 
Looking at 300 tiny capacitors, ranging from 2pF to 0.1uF made me think "Why do I mess with metal film caps?" and "Why do I buy small quantities of just a couple of values?.
The cost US$2.40, and there's 10 of each of 30 different values.  Except for the environmental waste in buying 300 and only using 50 over the next 5 years, it feels like I should done this ages ago.  My PCBs will be smaller and vero board designs will be easier (2.5mm instead of 5mm spacing).
But all of these advantages would be meaningless if, as some opinions have it, ceramic caps sound bad.  So..

Does anyone have any evidence that ceramic caps degrade tone?  In what way?  In what circuit?  Compared how?

Thanks!

[ElectricDruid]

Ceramic caps vary as the voltage across them increases, so they produce some distortion. Cheap ceramics can also be somewhat microphonic.

Whether either of these effects is significant at pedal voltages and neighbour-friendly volumes is an open question.

I do tend to avoid them for direct coupling in the signal path, but I'd use them for lots of other jobs in a circuit, and if I was building a fuzz I wouldn't care since it doesn't make sense to try and avoid minute levels of distortion in a circuit that produces tons of it anyway.

Here's a TI paper with some actual analysis, instead of the usual audiophile hand-waving:

https://www.ti.com/lit/an/slyt796a/slyt796a.pdf

[Dormammu]

I use several solid state amps built mostly with ceramic caps.
The sound is more than satisfactory.
The piezoelectric effect, if present, can spoil the work only high-frequency devices, not in the audio range.
I think all this mambo-jumbo with valves and film caps is long outdated nonsense.

[GibsonGM]

I also don't use them as coupling caps, 'just because'...but they end up here and there in circuits...maybe you don't have a .1u, and find a ceramic in the junk box. Have never had any negative effects that I can hear.     

If there would be some issue were they used in something that's supposed to be very clean, a chorus or delay for ex., I cannot say.  It would be interesting to mock up something just for grins.   

I'd tend to look more to resistors for noise/audible junk. I can't say how bad ceramics' ESR tends to be - could that have something to do with their negative reputation?

[MrStab]

Among other things:

https://sound-au.com/articles/capacitors.htm#s14

[Dormammu]

I agree with the electricdruid, if someone are afraid of distortion to shitting pants — make sense to strain and look for "magic" film ones, for interstage transitions.
And more practical advice, if you already have an amplifier with film caps — change a couple (or all) interstage and listen.

[Dormammu]

MrStab
Damn good advice.
I have to remember to hire a guy with a shotgun to keep the screwdriver scums away from my amps. Especially if someone give me a valvestate (by myself hardly ever buy for money)   

[MrStab]

MrStab
Damn good advice.
I have to remember to hire a guy with a shotgun to keep the screwdriver scums away from my amps. Especially if someone give me a valvestate (by myself hardly ever buy for money)   

You'll need to ask em to guard against all those deviant loudspeakers pushing nearby air, no-good kick drums and any guitarists or animate singers with shoe sizes exceeding 12! Hourly rate may increase as a consequence.

[Dormammu]

You'll need to ask em to guard against all those deviant loudspeakers pushing nearby air, no-good kick drums and any guitarists or animate singers with shoe sizes exceeding 12! Hourly rate may increase as a consequence.

They don't generate enough power for me to hear it through the caps.   
And I don't use valves (which also no joke - microphonic).

[amptramp]

Here is another example of capacitor non-linearity with voltage showing test waveforms:

https://diyaudioprojects.com/mirror/members.aol.com/sbench102/caps.html

[rutabaga bob]

I also use them for some things.  My aggravation with them is how out-of-spec some I've gotten have been; to have only two or three out of 25 or 30 parts come close.

[Mark Hammer]

I have an original Shin-ei FY-2, and used to have an original Maestro FZ-1S.  Both use only ceramics, and sound just fine.
So I concur with Tom.  That doesn't mean one should deliberately seek out bad caps for drive pedals, but you shouldn't worry about using them in such contexts.  Of course,the often wider tolerances of some ceramics may require a little more attention to measured value, rather than what the printing on the cap says.  If the objective is purity of multi-source wide-bandwidth sound, then cap material/type starts to gain more importance.

[MrStab]

They don't generate enough power for me to hear it through the caps.
And I don't use valves (which also no joke - microphonic).

From your conduct on this thread and others, I sense you don't quite understand the culture of this forum.

[Dormammu]

From your conduct on this thread and others, I sense you don't quite understand the culture of this forum.

I hope, that most of the visitors are adults, with a sense of humor and good logical thinking.

[MrStab]

Indeed they are, so whip out yer notepad!

If you're confident your use-case and numbers are limited, controlled and predictable, then use ceramics for coupling all you like. In all likelihood, it will be fine.

[antonis]

Does anyone have any evidence that ceramic caps degrade tone?  In what way?  In what circuit?  Compared how?

I DO..!!! 

(but you'll have to pay a lot of money to get all those documentations..)

[stallik]

When I first started building, I used many ceramics because they were freely available locally. I didn't have any issues but later learned that my builds might be better had I used film caps. Several years on, I'm using film caps but have yet to rebuild the original circuits to compare the results with my originals.

I'm sure that my soldering skills have improved over that time so, for accuracy, I'd probably need to build 2 identical layouts to compare and, to be honest, I haven't yet bothered

Has anyone done this?

[CheapPedalCollector]

I use ceramics but I use dipped ones, had issues with old ones absorbing moisture and becoming excessively noisy/leaky.

Only capacitor type I can hear a difference with is polystyrene, seem to be overly bright and harsh to my ears. Works well in some circuits where that's desirable.

I've had "engineers" instantly discount both of those links as nonsense and undetectable by the human ear... not so sure about that. I can't find the old study on phase shift over frequency range of various cap types, it's out there some where. Resistors do that too depending on construction and voltage across them. I don't think it matters much for a single cap or resistor, but the effect could become cumulative, would be interesting to test that, so it's like real world application and not some very strict lab test with only a single part.

[Dormammu]

I use ceramics but I use dipped ones, had issues with old ones absorbing moisture and becoming excessively noisy/leaky.

How do you determine the level of humidity in the caps?

[amz-fx]

If you have a pedal that has smt parts, the capacitors are probably all ceramic types.

This can be okay if the manufacturer/designer selects ceramics of the proper composition, but more likely they will be made with whatever the cheapest caps are on the smt reels at the factory.

regards, Jack