Design question, input reference to ground for op amps.

So I?ve seen two means to reference the input to ground on the API 312 (as example).
http://www.waltzingbear.com/Schematics/API/API_312.htm

With a very large resistor (R4 as 100K) followed by a very large cap(C5 a 1,000uf) , the cap blocking very little of the signal so the resistor must be bigger (?)

Or

A smaller resistor (R4 at 5-10K) with a very small capacitor (C5 as 50-100pf) the cap allowing very little of the signal to pass so the resistor can be smaller.

Both seam to reach about the same result. :?:

As this will come up with almost any opamp project I am wondering what the advantages or disadvantages of each approach is,

I could see using this as a low pass filter but the values in both cases seam to extreme. What would lead you to go one way or the other? I will play around with this, this weekend, but are there differences that may not be readily apparent to the ear?
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> a very large resistor (R4 as 100K) followed by a very large cap(C5 a 1,000uf)

Where have you seen that?

> smaller resistor (R4 at 5-10K) with a very small capacitor (C5 as 50-100pf)

This loads the transformer winding and controls supersonic ringing. Exact values should be suggested by the transformer winder or by experiment.

> reference the input to ground

The (+) input is referenced to ground by the transformer winding. This sets the DC level to ground, and the audio on the winding tells the op-amp what to amplify. Nothing else is needed to make it work. Any 100K broadband or 5K supersonic load is to control impedance seen by the mike or the stray reactances inside the transformer. The effect is subtle and sometimes inaudible, just to meet a spec or show a pretty trace on the oscilloscope.