I don't think there is a correct tuning as such, just a tuning that the drum sounds best at, or a small range. I think, in retrospect, that the D2 is too high for the resonant bass you mention. This weekend I will take it down a few semitones. Thank you so much for your help in this topic. It means a lot, information on working with these kinds of drums is so sparse on the internet, which is ironic given their age.