> What is the difference between a metallized capacitor and a film-and-foil capacitor?
Metalized has super-thin metal. The big "benefit" is that any weak-spots in the insulation will "burn out" quickly. This means they can use thin nonuniform insulation for large voltages in small sizes.
It is very good for bypassing noisy supply lines that might have extreme spikes. Get a 600V spike on a 400V cap, maybe 10% of the insulation will only stand 599 volts, it breaks down. BUT when the high current flows, it burns off the super thin metal, back to where the insulation is full thickness. After a few such spikes, the capacitance has dropped a few percent but the cap still works.
This is not so useful in audio. Obviously, if we ever do break-down the cap so it has to burn-out its weak spots, there will be a HUGE noise in the signal until all is cleared. And you need significant current to burn-out even the thin metalization, most audio signal paths don't have enough amps to do that, so the cap will just stay shorted. And the super thin metal is not a great conductor and may crap-up the audio.
Metalized has super-thin metal. The big "benefit" is that any weak-spots in the insulation will "burn out" quickly. This means they can use thin nonuniform insulation for large voltages in small sizes.
It is very good for bypassing noisy supply lines that might have extreme spikes. Get a 600V spike on a 400V cap, maybe 10% of the insulation will only stand 599 volts, it breaks down. BUT when the high current flows, it burns off the super thin metal, back to where the insulation is full thickness. After a few such spikes, the capacitance has dropped a few percent but the cap still works.
This is not so useful in audio. Obviously, if we ever do break-down the cap so it has to burn-out its weak spots, there will be a HUGE noise in the signal until all is cleared. And you need significant current to burn-out even the thin metalization, most audio signal paths don't have enough amps to do that, so the cap will just stay shorted. And the super thin metal is not a great conductor and may crap-up the audio.
