dramadisease
Well-known member
I've just finished up some api preamps based on the 312 circuit with a DI mod similair to Bo` Hansens (http://web.telia.com/~u31617586/API%20312%20DI%20mod..jpg) just minus the zeners and the protection diodes across the opamp inputs, and I seem to get a bit of noise when the gain is maxed out. Its a strange buzz that gets much louder when i switch it to di, but quickly dies back down where it was in the mic setting. I did use the 1M reference resistors, but mounted them on the MIC/DI switch (im going to try hardwiring them in the cards later)
it sounds like a wierd biasing thing with the opamp inputs. My opamp exp. is a bit on the limited side. Could someone lend a few ideas? also what exactly are the reasons for using the 12v zeners and the diodes across the opamp inputs? I figured the diodes were on the opamp as a rfi suppressant? Am I wrong?
thanks for the help!
-bryan
it sounds like a wierd biasing thing with the opamp inputs. My opamp exp. is a bit on the limited side. Could someone lend a few ideas? also what exactly are the reasons for using the 12v zeners and the diodes across the opamp inputs? I figured the diodes were on the opamp as a rfi suppressant? Am I wrong?
thanks for the help!
-bryan