Silver Mica Caps on Phono Inputs

 I have not seen this done. Perhaps it is due to the capacitors shunting to ground, and not affecting the signal path. MLCC caps are what I have used.

Yes, Ceramic is often used, possibly more than a film type.  Certainly, a ceramic COG/NPO is far less expensive than an equivalent size Silver Mica.

Folks seem to have some serious opinions about running audio signal current through a cap's dielectric, that is in series with the signal.  I just haven't seen much comment when the cap shunts the signal to ground.

Thanks!

Here is an update to this thread.  I've been researching Silver Mica caps for a few months now.  The more I looked at them, the more intrigued I became.

If you need a HF bypass, as in RF, it is hard to beat Silver Mica.  It beats COG/NPO ceramics in every parameter, except cost.  It has very low loss, very low ESR, and very low ESL.  For audio work where small caps are needed, they also do very well.  They are not microphonic, they are sealed environmentally, and have low ESR & ESL characteristics.   The plates are silver, hence the name.  

Unfortunately, I was not able to find any information or tests indicating whether polystyrene or silver mica is better for audio work where RF is not a question.  However, for RF bypass, such as phono inputs or amplifier inputs, they are clearly the best choice available. Polystyrene and Polypropylene do have higher ESR & ESL numbers than Silver Mica, so they are less suited for RF bypass applications on inputs. 

The only drawback is cost, these puppies are pricey!  Expect to pay 10x to 20x more than an equivalent COG/NPO ceramic cap.

I like and use silver micas for RFI .2200 pf. Very stable and clean sounding.