G'day all, of late I've been doing some interesting MM cartridge loading tests with capacitors and quite accidentally I've found WIMA polypropylene capacitors 'sound' much nicer than the ordinary ceramic capacitors that I normally use.
As I'm not a believer in so called boutique capacitors I am genuinely surprised by how nice these WIMA capacitors 'sound'. Are ceramic capacitors really this 'bad sounding' in this application? Regards, Felix.
As I'm not a believer in so called boutique capacitors I am genuinely surprised by how nice these WIMA capacitors 'sound'. Are ceramic capacitors really this 'bad sounding' in this application? Regards, Felix.
Ceramic come in a lot of varieties.
Polypropylene come in lots of varieties.
None need to be exotic audiophile to show differences in parameters.
Those parameter differences can be audible.
Choose the correct capacitor for the duty.
Polypropylene come in lots of varieties.
None need to be exotic audiophile to show differences in parameters.
Those parameter differences can be audible.
Choose the correct capacitor for the duty.
You seem to be missing the point, my Scottish friend.
Ceramic caps are typically used as the "correct duty" for cartridge load caps. Felix has discoverd that in fact WIMA polypropylene caps sound better - and that is what he is reporting.
I suspect that if he spent the next 6 months doing further tests, he would be able to find some other film cap that sounds even better - but that is not the subject of his thread. Felix simply substituted WIMA for ceramics.
Regards,
Andy
G'day all, since this 'discovery', my reading on this subject is generally very anti ceramic capacitors for all signal type path audio applications.
Ceramic capacitors certainly have their uses at RF frequencies though! As an active Ham Radio operator, I know that only too well, but not at baseband audio frequencies. Regards, Felix (vk4fuq).
Ceramic capacitors certainly have their uses at RF frequencies though! As an active Ham Radio operator, I know that only too well, but not at baseband audio frequencies. Regards, Felix (vk4fuq).
Ceramics can range from absolutely horrible for this application (e.g., X7R) to quite good (e.g., C0G). So the generic "ceramic" is not very specific.
G'day mate, yes I've read that. I suspect that the ceramics I have are of the cheap 'horrible' variety! Regards, Felix.
I have several ceramic caps to hand. They give their value ... but how do I determine whether they are "C0G (NP0)" or something worse-sounding?
Thanks,
Andy
Two easy ways. First, if you're confident about your ability to hear these differences without doing any sort of controlled listening test, just "listen" to them.
The second way, for those of us who are a bit more doubtful about human brains, is to put the caps on a meter, measure the capacitance, heat them up with a hair dryer for a few minutes, then measure again. The C0G will have a very small change in capacitance, other ceramics will change markedly. If you also measure the temperature of the cap after heating (I use a small kitchen IR thermometer for things like this), you can calculate the temperature coefficient and quickly determine which dielectric you're dealing with.
You can sometimes tell from the coloured band or hat worn by many small ceramic caps. I believe black means C0G/NP0. I don't know how standardised the other colours are, but you can probably assume that some other colour means not C0G/NP0.
If you know exactly what range your caps come from then the manufacturers datasheet should tell you. Low values are usually C0G/NP0, but the exact value where a different ceramic is used varies from range to range: it could be 33pF for one, 68pF for another.
Ceramics with poor temperature stability can also be piezoelectric and non-linear, and it is these issues which create the main audio problem.
If you know exactly what range your caps come from then the manufacturers datasheet should tell you. Low values are usually C0G/NP0, but the exact value where a different ceramic is used varies from range to range: it could be 33pF for one, 68pF for another.
Ceramics with poor temperature stability can also be piezoelectric and non-linear, and it is these issues which create the main audio problem.
1. If they have high values >100nF they are unlikely to be NGO.
2. If they are small compared to their capacitance, they are unlikely to be NGO.
3. If they were cheap, they are unlikely to be NGO.
You could also measure, but that gets a bit complicated. COG have very low tempco's, other ceramics are high. COG also has very little capacity variation under voltage, another difference you could measure given the right gear.
2. If they are small compared to their capacitance, they are unlikely to be NGO.
3. If they were cheap, they are unlikely to be NGO.
You could also measure, but that gets a bit complicated. COG have very low tempco's, other ceramics are high. COG also has very little capacity variation under voltage, another difference you could measure given the right gear.
C0G and NP0 are the low tempco ceramics.
X7R and similar are very good for decoupling in audio circuits.
Ceramics need to be chosen for their duty !
X7R and similar are very good for decoupling in audio circuits.
Ceramics need to be chosen for their duty !
I have spent many a happy hour having the microphonic ceramic capacitors changed in valve amplifiers! They are great as mains filters because of the impedance but tend to act like a condenser microphone because of its mechanical design. If the epoxy is loose, the ceramic plates can move.
Very true... I always use X7R for supply decoupling, but would never consider C0G for the same purpose.
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