Anybody do know the formulas or a web site for multi-poles RC low pass passive filters ?
The 2 pi rc formula seem not exact wen it is for a filter with more than one pole.
I did a Google search for passive filter but I did found only for one pole type formula or only generalities for the multipole type.
I want to do a 19khz RC type 4 pole low pass passive filter to put it before a mu-follower tube stage I-V output for a TDA1541 NOS Dac.
I found out that passive filter do have less phase shift than active type.
I did try with Tina but it's not easy to go by guessing and try and errors.