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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: The air-caps as an ultimate cap.Posted by Romy the Cat on: 6/12/2008
Paul,
in my view the air-caps as an ultimate cap, the ultimate by own intrinsic topology. It is particularly the case for the 834P- like application as in there the cap is not biased by high voltage DC and gets constantly re-polarized. You see the problem with capacitor is the electromechanical influence of dielectric. A capacitor might be visualized as a termination of transmission line where a dielectric acts as a brick wall. However, any dielectric has own ability to be polarized (Teflon I think is the best from this perspective) and doing it is acts as a very microscopic cone of loudspeaker, changing it’s proximity to conductor and modifying the transmission line termination. In case of air-caps there is no dielectric at all, so there is no variation or reflection from it with change of the signal. The vacuum caps that I was planning to use initially even advanced from this perspective fun but they have own problems. Is the air-caps that I used are the ultimate cap? Not really. To make it ultimate it would make send to build own fixed air caps. It is very simple to do – just an array of parallel cupper plates. I did not do it but I might try it another day if I have too much itch in my hands.
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