Not diy, but more likely to see responses here.
Can xmax be calculated from the surface area or diameter of a driver reliably? It seems when plugging the numbers into an excursion calculator , a 5.25” driver would need 16 mm of xmax to reach 50hz at 100dB @1m, yet I have no issue reaching 100dB @3m from 50hz on up with rp-150m’s 5.25” driver with <3% THD. I am positive the drivers do not have 16mm of xmax, more likely it’s about 6mm. The port tuning is 66hz. The 250c has dual 5.25” drivers and a tuning around 70hz, and can achieve 103dB @3.3m from 50hz on up. This translates to about 106 and 109dB @1m.
Assuming the port is reducing excursion across a ~20hz range, would a speaker using the same drivers in a tower with a 35hz tuning perform worse at 60-80hz when compared to the smaller box tuned to 66hz? For example, if the 250c using 2 5.25” drivers tunes to 70hz can output 109dB at 50-80hz, would a 250f, using 2 of the same drivers tuned to 35 hz require greater excursion from 60hz on up to achieve similar output?
Out of curiosity, how can excursion based on spl an frequency be calculated in a ported box without t/s parameters?
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