Well-known memberGDIY Supporter
- Apr 15, 2017
@rogs I tried dropping you a DM, bot i'm not allowed for some reason.I've used both the OPA1641 and 1642 in my various projects here: OPIC Impedance Converter
Unlike the design linked to in the 'instructable' above, I don't regulate the supply to the op amp, and get a little extra headroom as a result.
Using the single amp 1641 draws half the current, so that helps a bit as well!
The audio output is single sided - although the output is still impedance balanced - so there is no additional noise introduced by the resistors in the inverting second amp used for a differential audio output.
I've found the various configurations I've tried all work pretty well .. low distortion and low noise....
I just built your opic circuit on a perfboard for an extra Akg electret i have. Just as i was finishing the build i realized the capsule is coupled to half rail instead of ground on one end. The only reason i can think of is not to present half rail dc voltage across the capsule which might interfere with polarization charge within capsule. Is this the only reason, or am i missing something?