I'm attempting to construct a geophone amplifier and, as i normally do, neglected to pay attention to the resistor values when placing my parts order as i thought i had a pretty comprehensive collection of standard values on hand... out of the values listed, i think i had only one or two in my bins. this is the first application example i've seen with such uncommon values... is it that this is a highly tuned example circuit and requires this sort of precision to function? or are the values given a best of whats commercially available and can be replaced with closest values on hand? is there a downside to replacing some of the resistors with precision pots?

also, in the formula at the bottom, what do the two || represent?

cheers!

-sj