Why have capacitors improved so much over the years?

Why have capacitors improved so much over the years?

Not so with all caps

And as far as non-polarized (plastics etc) coupling caps go, the BEST CAP IS NO CAP, if the circuit allows for it to trim out any dc offset manually, or a simple dc servo can be installed. (direct coupled always sound better) but not all circuits can be dc coupled

As for polarized big or small electrolytic power supply caps go, some quality makes NOS (new old stock) can be very good, but very important they need to be "conditioned" first using an ac variac, over a couple of hours and bought up from zero very slowly to their max voltage.

Cheers George

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Capacitors have improved in certain ways due to designers looking and wanting a different type of sound than previous versions. The change in sound is due to using different materials and construction. I can say that the early capacitors due not sound bad at all if given time to re form in an old component. You have to give some time before you judge an old capacitor especially in an amplifier or speaker because most of the time they are not bad at all they just need time to play and re form. If you do change the capacitor to a new one it can sometimes cause the gear or speaker in question to sound very different, especially bright at first, due to the new cap needing to form as well.