[PD] biquad equation for vcf~?

[Maurizio Giri]

Hi, I'm trying to convert some PD patches to MaxMSP. 
However I have a problem with the vcf~ object, it seems it doesnt have an EXACT equivalent in maxmsp: reson~, svf~, and the filtergraph~ bandpass all sound different from vcf~
I'd like to use biquad~ to emulate a vcf~ filter, but I don't have the vcf~ formula to calculate the coefficients.
Does somebody know how I can calculate them?
As I said filtergraph~, reson~ and the other maxmsp objects are not identical to vcf~ so they are not good for my pourpose.

TIA!
mau