sabai
geoffkait,
Simply being direct and to the point. You stated, " ... you’re only guessing if you don’t use a SPL meter." Do you mean that Frank Tchang was only guessing? But then you stated, "It [Franck’s diagram] will get you around 50% of my SPL meter method." If so, nice to hear Franck made some good guesses and that your method is twice as good as Franck’s guess work.
Far be it from me to beat a dead horse but Franck Tchang’s diagram was designed SPECIFICALLY for HIS Special pure Gold, Silver, Platinum and Basic acoustic resonators thus are doomed to FAIL for the knock-off attempts of cheap DIYers. If a DIYer gets good result with Franck Tchang’s diagram it means you were lucky. It’s ridiculous to think that ALL speakers and ALL rooms would exhibit identical dynamic sound pressure mapping. One can't help wondering how Franck Tchang addresses sound pressure peaks that are NOT on any room wall but in the 3-D space of the room. Follow?
At the risk of repeating myself has anyone experimented with tiny bowl resonators smaller than the 7/8" Franck Tchang resonators?
Have a a nice day