iPhone mic jack

[Matthew Sanford]

Makes sense, so I'll try it that way so the phone sees the ground R first. Honestly I was just so happy to have it work at all, but the amount you've put into helping is overwhelmingly appreciated! I always feel the need to know the whys, and you have graciously supplied them through the questions that answers create as well!

I was wondering, the ratio of the cap:r for the lpf, does it change anything if the cap or resistor is a higher value, being that the math gives the same result? Or is the outcome for the signal the same whether big cap/small R or vice versa? I'm thinking it shouldn't, but the the cap is in position to couple audio...also would the cap value matter for dc blocking, or is it any cap would block dc?

I will let you know when I breadboard confirm correcting the ground r position

[Matthew Sanford]

I moved the 4.7k to the Vout (phone) side of the 100k and whattayaknow (you already knew  :icon_razz), it works great! I have the .1u in there right now with it...just didn't realize how important it was for the phone input to see the ground R first, but otherwise it sees it through and in addition to the series R.

Rob I can't thank you enough for taking the time to lead me down the path, and then go the extra mile! I have learned tons here, filling the gaps in my sporadic exploration style of learning this! My hat's off to you sir!

[Rob Strand]

OK cool, it's working.    You can change the 100k to a smaller value if you find the attenuation too much.   The choice of that resistor depends level of the external source.   If the "100k" is too large you have to crank the record level too much and you get noise.   If the "100k" is too small you will have to throttle the output of the source too much to prevent clipping.

[Matthew Sanford]

I may put a trim pot when I box it so it's somewhat adjustable, for different sources, but the 100k was setting it fairly well.