I use a 25W tube amp with a diy loudspeaker. This loudspeaker is made with a Fostex FE206E + FT17H on open baffle upon a bass enclosure with an Eminence Delta 12 LF. The problem is that the damping factor of this amplifier is not friendly with Delta 12LF and I have not enough dynamic and efficiency on basses. I need a RLC series notch filter before using bi amplification but I'm not sure how to calculate it. Does somebody could help me ? :(

Thanks.

Eminence Delta 12LF :

Re = 6,06 ohms
fs = 45 Hz
Qes = 0,45
Qms = 7,28
Impedance at fs = 93 ohms

Pascal / France