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By pass caps?

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  • LOUT
    replied
    Keep in mind that I'm NOT very experienced with any of this. This is mostly just parroting what I've been able to find/read so far.


    The hope is to get some of the qualities of Poly or Foil capacitors while keeping the size/uF and price benefits of NPE capacitors when they're together parallel.

    Some things that people might be aiming to avoid (or bypass) are ESR and inductance.
    Some of the controversy comes from how much benefit or difference you'll realistically gain....for example, ESR (the resistance of a capacitor that's often not listed in specs) is very frequency-dependant. NPE capacitors will have higher ESR/resistance at lower and lower frequencies and larger uF capacitors will have less ESR/resistance and it'll start climbing at far lower frequencies. This makes ESR much less of an issue because it naturally occurs in frequencies below where you'll likely use the capacitor anyway. It's a difference, but it typically happens where you won't notice much or possibly at all.

    I'm also unsure how effective a smaller bypass capacitor will help when its smaller value naturally impedes lower frequencies more effectively than the larger capacitor it's paired with...so I'm doubtful of how much help a 1/10'th size bypass cap would offer against ESR at low frequencies a ways below the XO point when the smaller bypass capacitor naturally wants to block those lower frequencies as much or more because of its low uF value.
    A bypass cap should still help against ESR at higher frequencies, but this is often less than 1ohm even without the bypass, so the difference is very small and too little for most people to hear.

    Inductance, on the other hand, should still be quite tweakable with a bypass capacitor. That said, I don't know how much inductance is typical for larger or smaller NPE caps. I also haven't been able to find/read whether NPE typically has higher or lower inductance compared to poly or foil (though it also looks like different build/styles of higher-end caps can have different inductance values via different design tweaks).

    Would really help if PE listed the inductance and maybe a graph of ESR for their PE/Dayton capacitors.
    In many cases these traits aren't inherently "goodVSbad", but simply something you can plan your build around when you KNOW they're there. Which would be a LOT easier to do if they were more commonly listed in the specs!

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  • Paul Carmody
    replied
    Nothing starts an internet flame war better than something whose effect can't be measured, but people swear they can tell the difference.

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  • a4eaudio
    replied
    Regardless of whether it actually works or not...what is the bypass cap supposed to do, according to those who would argue for one?

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  • ugly woofer
    replied
    Can open.........worms everywhere.

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  • johnnyrichards
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  • Unbiasedsound
    started a topic By pass caps?

    By pass caps?

    What do by pass caps do on a speaker xover? I just watched a video on it but want to know others opinions.
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