How to properly turn down volume, as overdrive~ is turned up?

    Oct 30 2012 | 1:17 am
    I'm trying to make a "smart fader" that will turn up the overdrive amount, while turning down the volume. I'd like the overdrive to really get crunchy, so I have the range going from 1 to 120db. 120db is pretty dangerous, so I want to do this correctly. Also, to make it smooth, I think an exponential curve is needed, which is still confusing. Attached is my hacked together attempt at this. Thanks for any help.