Hi Nerdz, I'm building a line in to eurorack converter using the Befaco In Amp schematics and I want to add a Sallen Key Highpass filter to remove 50 hz rumble Basically the Befaco inamp is 2 stages: The first opamp stage is doing a 2.2 gain, Through the potmeter to the second opamp stage Where would it be best to add the filter: 1 Before the inamp 2 In between the first and second gain stage 3 After the whole inamp Where would you integrate the Highpass filter, and could opamps be shared?   submitted by   /u/Successful_Range6999   to   r/synthdiy [link]   [comments]