[sdiy] feedback cap formula?

[mark s]

hello people

what is the formula for the size of the cap  in the feedback loop of a 
typical inverting opamp situation ? is it 2*pi*Rf*Cf ?  is the cap's value 
gain-dependent? in this instance, i am just trying to limit a TL072 to the 
audio frequency range, say 20 or 40kHz or whatever.

and would you recommend ceramic or a more audio-friendly synthetic cap?

thanks
mark