You had me scratching my head for a minute there.
Then I realized you are setting the Low Corner and High Cutoff, and solving for the Flare, yes?
In the case, it can turn out an m
parameter above or below the suggested range. The further away from this range you get, the less the "reactance annulling
" portion of the equations work. If you aren't worried about "RA
" it is no big deal. If you are you can correct the Vb, or alter the horn profile a little to adjust for it in Hornresp. Most of the time is it still pretty close.
Most of the time this is a function of going way over the drivers mass roll off frequency with the HC. You can find the equation to the right under "fH pos high
" the equation is =(2*fs)/Qts from Keele.
For a sub, I set the Flare and LC, and solve for HC. Sometime you just end up with a low HC. The TH-50 has a suggested bandwidth of 21-70Hz, and if you put the driver through the sheet you will see why.