FET volume control

I found the following circuit in the internet. Just started to study it but no sure how the volume up- down process work. Can you help me understand how it works. This is an n-channel FET so if the volume up when the voltage is negative? I would like to build it, can I substitute the 2N4093 ->> with a MPF102? (that is the one I have).


Thanks

it just charges a cap and uses the fet as one leg of an attenuator

Can I used MPF102 FET in this circuit?

FETs have a very wide range of specs. The circuit might work with one but not work with another even if they have the samew part number. Try yours.