AC Coupling Capacitors

Discussion in 'General Electronics Chat' started by Skeebopstop, Jan 7, 2010.

  1. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    358
    3
    Hi All,

    I've recently designed an audio amplifier and used low esr tantalum caps for ac coupling at the input stage. I checked against an international rectifier design and they do the same thing, except they use general purpose tants and not low esr.

    I read a white paper showing that ac coupling with low esr tantalums, in particular NiOb, provides minimal THD and compares adequately to other really expensive types. I am unsure if the setup for the white paper was using a Class A amplifier for test or not.

    I guess what I find a bit odd in doing this is that they are 'polarized' caps coupling an ac signal which in some situaitons may not be DC biased and thus have a negative component.

    Originally I was using multilayer chip capacitors but after some reading found out they can introduce a fair amount of distortion so I changed. The tantalums are working great from 3 different pre-amp sources (I'm assuming 3 differing pre-amps from 3 differing applications, all of modern devices, won't be using class A biasing).

    Any comments? All my reading thus far has only really provided cautionary measures when using electrolytic but said little about tantalum. I have seen some forums where people mention audio equipment companies sometimes use aluminum electrolytics (perhaps they designed a class A preamp stage though).
     
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