
Unity Gain Sallen Key Filters courtesy of Rod Elliot.
http://sound.westhost.com/articles/acti ... ers.htm#s3
Correct. Make sure one resistor is always in circuit to provide a bias current path. I honestly think for a LF mono crossover single order would be best. A low bias op amp (LME49860 or Bifet) would allow a relatively high shunt R value and allow the use of film caps.I'd like to be able to have say 4 or 5 selectable frequencies, and with the 2 order one that may be too complex if I have to change more than 1 component etc, with 1st order I believe it's just changing the shunt resistor, I believe.
I think you mean 796 Ohms for a 20 Hz cutoff.Think I'm working out that design with a 10uf series and for 20hz cutoff a 795k shunt.