Yes, I used to see the odd big high voltage capacitor in labs, the ones with some serious corrugated ceramic insulators for the terminals. If the lab folks knew what they were doing there was always a sturdy wire screwed down to short the terminals. The other rule of thumb was to always assume that a cap you were handling had a charge.
Once I was working on a ~kilowatt subwoofer amp with a Carver-esque design, one which had no bleeders across the supply caps. I fumbled while probing, and despite having the unit off for a while, after the bang sent me reflexively recoiling, I found that I had induced a large enough transient in a ground trace to blow up several opamps on the board
. That was an unpleasant evening.Assumptions will prevent perfection -
Here is a common assumption that prevents the crossover from being what the sim software says will result. Some assume the phase angle will be 90 degrees but never measure it at the freq to be used. The attachment is of an air core 'perfect' inductor used in speaker crossovers that I measured. Problem is that the phase angle is not constant 90 degrees over freq range and its value can actually only be counted on at 1KHz. You wont get the desired crossover response if the cap is not 90 degrees assumed value..... unless you raise the coils Q at lower freqs by introducing a ferrite core or the like. Its the many little things like this which cause us to fudge/tweak the results to get what we wanted for a result. But, that is never really satisfactory as a better part for the app. --RNM
Here is a common assumption that prevents the crossover from being what the sim software says will result. Some assume the phase angle will be 90 degrees but never measure it at the freq to be used. The attachment is of an air core 'perfect' inductor used in speaker crossovers that I measured. Problem is that the phase angle is not constant 90 degrees over freq range and its value can actually only be counted on at 1KHz. You wont get the desired crossover response if the cap is not 90 degrees assumed value..... unless you raise the coils Q at lower freqs by introducing a ferrite core or the like. Its the many little things like this which cause us to fudge/tweak the results to get what we wanted for a result. But, that is never really satisfactory as a better part for the app. --RNM
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??? Really? A lot of people dont measure the phase angle of the actual physical inductor they are using at the freq of use and only assume its value. More series R would make the phase angle or Q less and thus make the problem worse. This is commonly overlooked.
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Guys, do we review here elementary math and physics involved in calculations of LC-filters, or talking with John about sneaky hidden tricks of High-end design?
Here is the page with links on JavaScript scripts that solves such problems: Pronine Electronics Design - Electronics Link Collection -- "2. Electronics Calculators"
Here is the page with links on JavaScript scripts that solves such problems: Pronine Electronics Design - Electronics Link Collection -- "2. Electronics Calculators"
Sooo literal; Examples or proof of concept and the like to get across something --- I am not discussing inductors.... nor caps, really ...follow the thread of thought -- tests that cause issues in listening results are often due to unknowns or assumed things. Like this and that. parts that make up the final product and some known and maybe unknown properties.
yes, a literal L interpretation would be good to put in the speaker forum. But seems to confuse only here.
yes, a literal L interpretation would be good to put in the speaker forum. But seems to confuse only here.
Its what ever you want to bring to the table as an issue. Go ahead. Whats ya got to offer?
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Thanks for replying.
I assumed that since you were referring to some mathematically characterized behavior, there would be some massive data behind.
From what I know, in a capacitor there is a proportionality between potential V and charges Q of the two plates. The proportionality is C (Q=CV) and C = eA/d
This proportionality holds in general, save for electric field non uniformity due to geometry (plate edges and plate surface irregularities) and dielectric non-homogeneity (plus localized or intentional bulk conductivity-leakage)
Therefore, I don’t understand what you want to convey:
Why you discriminate between capacitor and dielectric here?
Response on what and symmetry in reference to what?
?
What do these curves represent (axes)?
Yes. Studying the complexities of dielectrics electrical impedance is of great importance for a few big $$ engineering fields. High power electricity (insulators), aerospace (all-composite construction of air vehicles) and of course microelectronics.
George
It is the formulas which could predict the outcome IF the values used were the same as the physical part you will really and truely use. Often the part has to be measured completely and thoroughly to be able to use the formulas that will then get you the expected and predicyted results. Its the same with sims on semiconductors... you have to actually know all the parameters to get accurate results which means tests the physical parts. I know this is obvious to most but it needed to be made a strong point of mine -- real parts have imperfections, variations and secondary degree parameters which can make a big difference in a particular app. Also if they reality dont match the sim, the listener will often tell you so. --RNM
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Apparently that's easy to do by measurement- see the curve fitting Jones did in Valve Amplifiers 4th ed. He modeled a large imaginary capacitance in series with the normal 1/jwC and saw large differences in that value between dielectrics.
By ear... well, I won't say "impossible," but "unlikely and to date totally unsupported by actual evidence."
Even transistors can sing horribly when stressed/overdriven. Why? (*)
And the harmonic content of the distorted output changes when the “ singer” is damped with a finger touch (this simply means that the mechanical motion in turn distorts the electric signal, i.e. microphony).
George
(*) I have placed a question sometime ago:
And now it’s a good time for some cascaded speculative questions.
1) Does the ac electromagnetic wave while passing along electrical conductors exercise real (mechanical) stresses on the conducting material (assume non-ferromagnetic)?
People working in high power circuits or in low power but minute dimensions may have some relevant experience for to answer.
Thanks
Ok. John. I'll be over at the headphone amp area, dsp and room correction and all manner of things of interest. I have things to build and listening to do and tests to make.
PS - There are better tests that correlate to what is described. use them.
Hey. I'll come back some day. C.U.L.ater -RNM
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