On Feb 5, 8:38 pm, Franc Zabkar
Why does the WES catalogue advise that Jamicon WL-R miniature low ESR
capacitors are "not suitable for audio"?
Well, for example in ceramic capacitors with dielectrics like Z5U that
is the same as Y5V, have the characteristic that the capacity is ONLY
and ONLY achieved under bias. That meant a 1uF ceramic capacitor is
only 100nF at 0.2V DC bias and ~1uF at 10V bias, etc. In audio
applications you use capacitors in various functions. In power supply
you don't care about such properties, because you always try to run at
full rated voltage of the supply. However if you were to use such
capacitor in oscillator or filters, you would get very large nonlinear
distortion. I personally tried some small, cheapest ceramic capacitors
(I think Z5U dielectric or similar) and I could tune oscillator
frequancy depending on capacitor bias voltage with one finger on
capacitor terminals and the other touching supply or ground. It was
fun.
Now back to your question. Electrolytics should not have much
nonlinearity at all. Maybe the double-layer capacitors before
activation, or multi-electrolyte type formulations could have more
exponential characteristic than is usual. But is is only a remote
possibility. Maybe the question was whether you want also to use it as
a bipolar non-biased capacitor. Soem 10 years ago I used electrolytic
capacitor in an application which required only alternating current
and of course the electrolytic capacitor - being only low current
UNIPOLAR type smoked the electrolyte out. That is what are BIPOLAR
electrolytic capacitor for. You ask WHAT is the difference? The main
is the electrodes, being of aluminium foil, one is oxidized and one
isn't. Bipolar capacitor has both electrodes oxidized (as far as I
remember, weak, weak memories
). Think about it briefly, would you
use an electrolytic capacitor with reversed polarity? Of course
not
. And that should be the most obvious matter on use of unipolar
electrolytic capacitors in audio. Oh, forgot to mention what happens.
Electrolytic capacitors have LIMITED lifetime. Wrong polarisation will
result in much faster electrode corrosion and will greatly shorten the
useful life. In audio path you want to use capacitors that will last
and not change their parameters over time. In switched power supplies
the capacitors have very short life, some will become useless in years
and develop gas pressure from decomposition and heat inside. reversing
polarity would much accelerate that.
If you want to use it under biased conditions of in a power supply,
you don't need to worry about capacitor being suitable for SMPS or
AUDIO, it only needs to be able deliver the current and not overheat
during that.
