[sdiy] X7R Ceramics for coupling AC audio

[Neil Johnson]

You can certainly get high-value (10's to 100's of uF) X5R capacitors, and they are cheaper than their Aluminium equivalents.

However, as the Wolfson paper puts it:
   best:  tant or Alu, low ESR
   OK:    X7R
   cheap: X5R

As for the DC effect, for small signal circuits the change in capacitance will be small.  For X7R the capacitance change with voltage is a few %, but for Y5V its huge, up to 80% over the operating range.  So running a reasonable-amplitude AC signal through a Y5V ceramic cap certainly would distort it.  For a 10V-rated cap a 1-volt swing is enough to affect the capacitance quite alot.

Really, someone with some time to burn should get hold of some of these X7R and Y5V capacitors and have a listen - then we'll have a real example to discuss.

Neil


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http://www.njohnson.co.uk

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