https://tunableapp.com/notes/db3/quarter-comma-meantone/
Db3 in Quarter-Comma Meantone: Frequency & Formula | Tunable
Db3 is 137.500 Hz in Quarter-Comma Meantone. Each perfect fifth is narrowed by 1/4 of the syntonic comma . See the chromatic scale comparison.
quarter comma meantonefrequencyformulatunable