Philbo King
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All of these things can be fully described with numbers. So why use "good/excellent/fair"? Is the intended audience stupid people? Just wondering...
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Capacitor distortion
- Thread starter pma
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That's the "subjective" part. IMO it's nice to have a simple summary like that, then you can dig into the numbers to dive deeper.
somebodyelse
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Because they will vary by voltage, capacitance and product line, not just by dielectric material.
PlasticDoc
Member
Perhaps you can point us to a more suitable table and the corresponding scientific article? Just wondering...
My eyes glossed over as soon as I saw "audio grade". Dose this pass as university research these days? Just enough knowledge to be dangerous comes to mind.
PlasticDoc
Member
Perhaps you can show us a better table and paper from another time?
It would be even better if it was something you published.
PlasticDoc
Member
Thank you for sharing. Your perspective is appreciated.
We also do not like snake oil (although it is worth noting that the table you referred to includes some beneficial plants, unlike snake oil) but it is for other reasons, in Medicine we value objectivity and rely on published and peer-reviewed scientific work.
Therefore, we avoid using biased or emotional language and we are cautious about criticizing the work of others and only do so when we have better research to offer or refer to.
Which brings us to the problem at hand: capacitor distortion. Can you provide or refer to a more practical table or a published paper that better illustrates this problem?
Warmest regards.
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Philbo King
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Here is (part) of a series that sheds some light on capacitor limitations.
blog.knowlescapacitors.com
Capacitor Fundamentals: Part 5 – Dielectric Properties
Capacitor Fundamentals Series Part 5: discussing five dielectric properties that affect capacitor performance
blog.knowlescapacitors.com
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A tantalum is a semiconductor capacitor an MUST have a DC voltage across it. It cannot be used with AC signals unless it is biased with a DC voltage higher than the AC.
An electrolytic capacitor also should have a DC on it. When this is not possible they should be used in anti-series which is equivalent to a bi-polar capacitor.
I prefer to use the term non-polar for capacitors without an electrolytic.
In this case (AC coupling) the problem is not the voltage across it (there should not be any) but the current flow (which there is) which is the problem.
Biassing the electrolytic lowers this distortion.
Would be fun to test perhaps using a battery in series with the load resistor for instance.
Tantalum are very poor audio coupling caps but work well as power supply rail caps. Also not very suited for low leakage current applications (timers).
Another option for tantalum is to use 2 in anti-series and bias the middle with an appropriate DC voltage but this better be very low noise
I often see electrolytics used in the feedback path of a power amp (to ground) which also is poor practice. Also sometimes see electrolytics as an input capacitor on amps without any bias voltage. Poor engineering.
FWIW, tantalums with solid electrolyte are preferred by a lot of folks who repair and restore old computers, particularly the very early Macs, because they don't have liquid electrolyte that can leak all over the board, as the original capacitors in those machines often do. But yes, I've always heard they're not recommended for audio signal paths; and the Mac restorers I'm familiar with use them only on the main logic board, not in the PSUs.
Ceramic caps are pretty horrible, too, as coupling capacitors due to their piezoelectric properties that contribute nonlinearity (distortion) to the signal.
somebodyelse
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Does that not depend on the type of ceramic? From what I remember its true of high-k ceramics like X5R, but not of C0G which had low distortion when tested, comparable to the best of the film caps.
Could be, most of my experience is with XnR decoupling caps and some RF coupling caps (which may have been C0G, been too long...) I know some of the capacitor companies were making specialized ceramics for transmitter coupling caps but I have no idea their specific dielectric after several decades away from the high-power stuff. You are probably right, I have a vague memory of seeing the same test results showing C0G was decent...
solderdude
Grand Contributor
C0G/NP0 (class I) are really only available in low values so fine for filters and such (< 10nF) for coupling caps one often needs bigger values of 0.1 to 4.7uF so ends up with something like X7R (class II) and higher voltage ratings (which helps a bit) IF one is confined to small sized MLCC caps .
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The capacitor table also includes some beneficial information, buts its rather vague, that was my point.
As do we EE's.
This is an audio forum not a scientific journal. There is better research, Philbo king has provided some
Knowles Precision Devices Capacitor Basics
Read this series to make informed decisions about multilayer ceramic capacitors (MLCCs), single layer ceramic capacitors (SLCs), and trimmers.
info.knowlescapacitors.com
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www.ti.com
Thanks and likewise.
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PlasticDoc
Member
Perhaps of interest to this thread is Cyril Bateman's - Capacitor Sound?, Electronics World Magazine, 2002~2003:
Capacitor Sound?, EW, jul 2002
Capacitor Sound 2, EW, sep 2002
Capacitor Sound 3, EW, oct 2002
Capacitor Sound 4, EW, nov 2002
Capacitor Sound 5, EW, dec 2002
Capacitor Sound 6, EW, jan 2003
or, if you prefer it in a single file with slightly better quality: Capacitor Sound?
Capacitor Sound?, EW, jul 2002
Capacitor Sound 2, EW, sep 2002
Capacitor Sound 3, EW, oct 2002
Capacitor Sound 4, EW, nov 2002
Capacitor Sound 5, EW, dec 2002
Capacitor Sound 6, EW, jan 2003
or, if you prefer it in a single file with slightly better quality: Capacitor Sound?
There were a lot of mistakes in the Bateman articles (it would have been a good idea to have his polymer stuff checked by an actual polymer scientist), so take it with several grains of salt. And of course, his test setup was not relevant to many common capacitor applications like coupling.
PlasticDoc
Member
solderdude
Grand Contributor
Most people tend to forget that because differences between capacitors (in certain conditions) can easily be measured does not automatically mean it can be heard too.
Low voltage, low current usage differs from high voltage/current usage for instance (there are no MLCC there)
Coupling and decoupling also require different properties.
It's a bit like only looking at SINAD numbers to base a purchase decision on.
Low voltage, low current usage differs from high voltage/current usage for instance (there are no MLCC there)
Coupling and decoupling also require different properties.
It's a bit like only looking at SINAD numbers to base a purchase decision on.
In audio? Probably a lot of hot air and bullshit (other than my own debunking of "capacitor sound" for coupling caps). Capacitor choice is a matter of engineering for the application, which "audiophiles" have no real interest in learning about.
Capacitors as an obsession is a weird cultural thing in fashion audio. I can blame Dick Marsh for much of it, but he was in it for the money and managed to do quite well pumping the superstition machine.
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