An externally hosted image should be here but it was not working when we last tested it.

http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

The input impedance of my amplifier is 50K ohms.

The desired high pass filter frequency is 85Hz.

If the value of C is given by the formula

C = 1 / (2 × pi × R × F)

How do I calculate the value of R? And what is the

*purpose*of parallel R with respect to amplifier input impedance?

Apologies for my novice understanding of electronics!

Thanks.