A cap in series isn't a linkwitz transform. It is a highpass filter that slightly moves the response curve to the left and gives a 5th-6th order roll-off. Infinity used to do it alot in many of their speakers in the 80's and 90's. Also, did you mean 1.2uf (microfarad) or did you mean 1.2mf? (milifarad) 1.2 microfarad will roll sub of around 5Kz, 1.2 milifarad around 20Hz. Don't put a 1.2uf(!) cap in series with the woofer.... And if you are talking about a 1.5milifarad cap, good luck finding one! You'll have to put a few huge electrolytics together (but they may not handle the power) or an ass load of film caps, that will be some serious$$... A linkwitz transform will be an Eq circuit that is the inverse of the roll-off below resonance. So if you are down say 12db at 20 Hz, it introduces 12db of gain at 20Hz and so on and so on. This is normally used in a sealed alignment that operates entirely under resonance. It takes an ass-load of power to get loud low with it also... It is an active circuit before the amplifier. I used a linkwitz transform with one of my XXX 18s in a .5ft3 sealed alignment with 2.5 KW. It worked OK, but you loose alot of output compared to a more efficient, larger alignment...