Hi all!
I would like to learn more about the differences between ideal and real-world capacitors, for audio applications. I know about the concepts of ESR and ESL and the non-infinite resistance between the plates in a real capacitor. From given values of these quantities I can calculate their effect on the impedance as a function of frequency, but I would like to see results from actual measurements. I have never seen anything about capacitor non-linearity, so any insights about that is also interesting.
Also, does anybody know how well the concepts of ESR/ESL reprecent the "non-ideality" of capacitors? For the capacitors I'm looking at for the moment, the ESR is given at 100Hz. Should I expect the ESR to vary as a function of frequency?
It would be very nice to see impedance measurement plots for commonly used capacitors (cheap and expensive) used in tube audio amplifiers, for the range 20Hz-20kHz, both high voltage electrolytics, polypropylen and ceramics, as well as lower voltage electrolytics. Actually, I am mostly interested in guitar/bass amps, so 30Hz-10kHz is a more relevant range.
I want to know at which frequencies the non-ideal aspects of these capacitors come into play, if this is inside or outside the audio spectrum, and if there is a difference between the impedance of cheap and expensive capacitors within the same spectrum.
This would involve e.g. electrolytics around the capacity of 47uF, and polypropylen capacitors in the region of 22nF, all with voltage tolerances above 400V. Also, e.g. electrolytics at around 22uF but with lower voltage rating, e.g. 25V.
Does anyone know of such studies that are available on the net? I have not found anything yet, but not everything is easily found with google, so I'm trying my luck here
I would appreciate any references that go beyond the mathematical model using the ESR/ESL concepts. Do any of the manufacturers present impedance plots of their products?
Thanks,
Torquil Sørensen
Norway
I would like to learn more about the differences between ideal and real-world capacitors, for audio applications. I know about the concepts of ESR and ESL and the non-infinite resistance between the plates in a real capacitor. From given values of these quantities I can calculate their effect on the impedance as a function of frequency, but I would like to see results from actual measurements. I have never seen anything about capacitor non-linearity, so any insights about that is also interesting.
Also, does anybody know how well the concepts of ESR/ESL reprecent the "non-ideality" of capacitors? For the capacitors I'm looking at for the moment, the ESR is given at 100Hz. Should I expect the ESR to vary as a function of frequency?
It would be very nice to see impedance measurement plots for commonly used capacitors (cheap and expensive) used in tube audio amplifiers, for the range 20Hz-20kHz, both high voltage electrolytics, polypropylen and ceramics, as well as lower voltage electrolytics. Actually, I am mostly interested in guitar/bass amps, so 30Hz-10kHz is a more relevant range.
I want to know at which frequencies the non-ideal aspects of these capacitors come into play, if this is inside or outside the audio spectrum, and if there is a difference between the impedance of cheap and expensive capacitors within the same spectrum.
This would involve e.g. electrolytics around the capacity of 47uF, and polypropylen capacitors in the region of 22nF, all with voltage tolerances above 400V. Also, e.g. electrolytics at around 22uF but with lower voltage rating, e.g. 25V.
Does anyone know of such studies that are available on the net? I have not found anything yet, but not everything is easily found with google, so I'm trying my luck here
I would appreciate any references that go beyond the mathematical model using the ESR/ESL concepts. Do any of the manufacturers present impedance plots of their products?
Thanks,
Torquil Sørensen
Norway