Never tried the Betsy K
(Misco?) I can give you volumes for Qtc = .707 / .8 /.9
By rule of thumb EBP = 91 so closer to wanting vented alignment
But Sealed does look good around 1.5 to 2 cubic feet
Im Familiar with Visaton BG20 8" about the same
1.8 to 2.3 Cu Ft doing the same thing adding a tweeter.
8" directionality leans around 1500 to 1800 Hz crossover.
So its interesting and looked at larger diameter tweeters to cross low.
What planar you looking At ?
Attached Transfer Functions for just about any alignment you would care to
use for the K
Sealed Qtc for .707 = 2.2 ft^3 yellow
Qtc .8 = 1.3 ft^3 pink
Qtc .9 = .95 ft^3 red
Vented Alignments = Gray line
Quasi Butterworth 3rd order ( QB3 )
4.8 ft^3 / 43 Hz Fb
Big Bass 4th order ( BB4) = Green line
2.8 ft^3 / 50 Hz Fb
( basically tuned to Fs, BB4 always tuned at Fs)
I like tuning below Fs if possibly looking at vented curves
I would take the BB4 volume 2.8 ft^3
then use lower tuning closer to Butterworth about 45 Hz Fb
and call it a day , or run sealed 1.2 to 2 ft^3
pretty forgiving even small box 1 cubic is less than 1 dB bump
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