AES: Evaluating Electrolytic Capacitors Specified for Audio Use: A Comparative Analysis ......
This paper is Open Access
This paper provides a number of comparative, quantitative evaluations of 10 different makes and models of electrolytic capacitors. Models range from expensive parts specified for use in audio circuits to low-cost general-purpose parts. The datasets comprise out-of-circuit electronic measurements, total harmonic distortion (THD) fast Fourier transform (FFT) sweeps, and cumulative distortion products resulting from 31-tone stimulus performed on the components in a circuit designed to emulate a typical line-level audio recording and mixing console. Results are examined in an effort to identify any measurable properties that may distinguish “audio capacitors” as outliers from their general-purpose counterparts.
I have only glanced at this; have not read it.
This paper is Open Access
This paper provides a number of comparative, quantitative evaluations of 10 different makes and models of electrolytic capacitors. Models range from expensive parts specified for use in audio circuits to low-cost general-purpose parts. The datasets comprise out-of-circuit electronic measurements, total harmonic distortion (THD) fast Fourier transform (FFT) sweeps, and cumulative distortion products resulting from 31-tone stimulus performed on the components in a circuit designed to emulate a typical line-level audio recording and mixing console. Results are examined in an effort to identify any measurable properties that may distinguish “audio capacitors” as outliers from their general-purpose counterparts.
I have only glanced at this; have not read it.
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Very subjective. No frequency is stated in testing the specific capacitors but suffices to say, the most expensive are usually no better than a standard run off the mill decent grade electrolytic and there is no such thing as "Audio Grade", that phrase is meaningless to an engineer and money making to the sharks that sell them.
Engineers and Scientists actually design these things so it's not meaningless to the designers.
They (eg Nichicon) aren't just taking standard grade capacitors from their product line then re-labeling them as audio.
I agree there are sharks that sell bs products, I am not sure I would necessarily put Nichicon into that kind of category.
Maybe the differences are infinitely small, but at least it appears they (Nichicon) are attempting to make a capacitor that best meets the demands of audio.
I hate that these companies don't actually explain (from a parameter point of view) how a specific cap range might be more suitable for a specific application over another application.
Have you noticed the new Automotive grade capacitors, they appear to be able get quite a lot more storage capacity per unit size than standard capacitors.
14,000uF from an 18mm 25V capacitor is quite a lot.
http://www.digikey.com/product-detail/en/united-chemi-con/ELBK250ELL143AM40S/565-4346-ND/5824549
I have not read the entire paper, but it appears they are testing within a circuit rather than in isolation. I am not sure testing in a circuit would really be a great way to rank or assess capacitor performance.
If the circuit used has 40dB of feed back this would not be the best way to rank and assess performance differences in capacitors.
It would certainly be ok to test for in-circuit performance (for a specific product) but every circuit is different, some have zero feedback for example.
Then there are also thermal effects to consider, are these tested at different environmental conditions, eg A class A amp could have chassis temperatures of 60 deg C etc. Some caps could be affected significantly at these temperatures while others might not be affected at all.
There is obviously also durabilty to consider if the cheap capacitors last a fraction of the time of the more expensive ones, then it's not a cost saving to try and save $4 in parts per amp if the thing fails in 12 months and it ruins your business' reputation.
If the circuit used has 40dB of feed back this would not be the best way to rank and assess performance differences in capacitors.
It would certainly be ok to test for in-circuit performance (for a specific product) but every circuit is different, some have zero feedback for example.
Then there are also thermal effects to consider, are these tested at different environmental conditions, eg A class A amp could have chassis temperatures of 60 deg C etc. Some caps could be affected significantly at these temperatures while others might not be affected at all.
There is obviously also durabilty to consider if the cheap capacitors last a fraction of the time of the more expensive ones, then it's not a cost saving to try and save $4 in parts per amp if the thing fails in 12 months and it ruins your business' reputation.
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I find this an extremely brief document. If I were to replicate the five tests described I would have a hard time doing this. The 31 tone test signal for instance is not specified. I made one myself using Audacity but for all that's holy I cannot find that file back. 31 tones suggest a lowest frequency of 20 Hz and highest of 20 kHz with the frequencies in between in 100-125-160-200-250-315-400-500-630-800 steps. I recall it sounded weird. I also miss the exact circuit diagram, only a block diagram is given and that it's build with NE5532AP opamps. It could be that the missing information can be requested from the researcher. Also note that it doesn't cover power supply capacitors. But that would make the study much bigger...
What?? All this guy did is to measure distortion??? No square wave, no ripple test nothing?? Not even frequency response?? Temperature etc.... How does it affect the capacitor??? How about run-in?? After 100hrs of run-in, any changes?? Charging rate, discharging rate?? Nothing.....
And then, no citations, no references nothing......You call this paper???
And then, no citations, no references nothing......You call this paper???
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He referenced Cyril Batemans work as well as D.Self. Not sure what you want? It's not a full AES peer reviewed paper, just an Engineering report.
At the end of the day it just confirms what Bateman and Self said many years ago, which is that electrolytics are fine when there is no appreciable signal drop across them (blocking duties in a console).
At the end of the day it just confirms what Bateman and Self said many years ago, which is that electrolytics are fine when there is no appreciable signal drop across them (blocking duties in a console).
For a start capacitors don't need to be "run-in", other useful parameters are available from datasheets. The aim of the paper was nothing more than an evaluation of capacitors for audio use with distortion as the measurement data as the title states.
The author is not an engineer and has a Bachelor of Music degree inTechnology In Music And Related Arts, so you would need to re-align your expectations with this in mind.
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I think escksu just wants to blurt out anything, having not reviewed his own post content before posting.
Perhaps he doesn't appreciate what a plot with Hz on the x-axis means, or a section called references indicates. Perhaps he didn't even get past the first 3 words of the title of the paper and what the title implies the content will be about:
Evaluating Electrolytic Capacitors Specified for Audio Use: A Comparative Analysis of Electrical Measurements and Capacitor Distortion Products in Line Level Interstage Coupling Applications.
Perhaps he doesn't appreciate what a plot with Hz on the x-axis means, or a section called references indicates. Perhaps he didn't even get past the first 3 words of the title of the paper and what the title implies the content will be about:
Evaluating Electrolytic Capacitors Specified for Audio Use: A Comparative Analysis of Electrical Measurements and Capacitor Distortion Products in Line Level Interstage Coupling Applications.
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For those who don't believe break-in is necessary, someone from our forum has shown it to us using an oscilloscope.
Capacitor Burn-In/Break-In
This is also why I stress that testing brand new capacitors are pointless.
Capacitor Burn-In/Break-In
This is also why I stress that testing brand new capacitors are pointless.
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