It would be interesting to have a short lesson from you regarding the calculation of the resulting ripple and what values you are aiming for in such a design. (MicPreAmp). Of course, only if your schedule allows it!

As Abbey says, you can work out the base level ripple from C.dV = i.dt

Where C is the value of the cap right after the rectifier, dV is the ripple voltage (peak to peak), i is the load current and dt is the period of the waveform. Abbey rearranged it into a more useful form:

dV = i x dt / C which can itself be rearranged into the even more useful form of:

dV = i / (f x C)

where f is the ripple frequency (usually twice the mains frequency for full wave rectifiers)

In your example, with a 10mA load and a 47uF capacitor, the ripple will be 2.13V pp.

The following RC stages each reduce the ripple by an amount equal to:

2 x PI x f x R x C

which for a 47uF cap and a 3K3 resistor gives a reduction of 97 times or very nearly 40dB. So three stages like this will reduce the ripple by about 120dB. I always rememeber 60dB converts volts to millivolts and another 60dB converts millivolts to microvolts. So the ripple should be less than a couple of microvolts.

Cheers

Ian