To use these tables:
Find the Qts of the driver in the first column
Read off the value in the Vas/Vb column, call it alpha
Vb=Vas / alpha
Read off the value in the Fb/Fs column, call it h
Fb = h*Fs
(similarly one may calculate the points where the system is down -3dB or -10dB by doing the same with the values in those columns.
There are two alignments that only work for one value of Qts for a given value of Ql
Butterworth 4th order has maximally flat response
For Ql=7,Â
Qts=0.4048, Vas/Vb=1.0613, F3/Fs=1.0, Fb/Fs=1.0, F10/ Fs=0.7598
Bessel 4th order has maximally flat delay
for Ql=7,
Qts=0..3312, Vas/Vb=1.9076, F3/Fs=1.4941, Fb/Fs=0.97354, F10/ Fs=0.86675
The next alignments work for many differnt values of Qts so will be given in tables.
QB3 and SQB3 table for Ql=7 (Dividing line is Qts=0.4048)
SQB3 has progressively more peaking as you increase in Q from 0.41
SC4 and C4 table for Ql=7Â (Dividing line is Qts=0.4048)
SC4 have slightly better transient response than QB3, but less bass extension.
C4 alignments have a ripple characteristic above and below the reference line of 0 dB.