First, thank you for 18" plans.

I meant push-pull in face-to-face - "Isobaric" - arrangement, as for example on http://diyaudiocorner.tripod.com/images/clam.gif. The box volume has to be 1/2 in this case.

When I connect speakers in parallel, I suppose that impedance pas from 8 Ohms to 4 Ohms (rough approach...) so I suppose the only change I have to do is modify L3 accordingly. I imagine two possibilities: to raise the value of L3 from 5mH to 10mH and put 2 woofers in parallel: 2L-(W||W); or to keep 5mH with each woofer and put the combo in parallel (L-W) || (L-W). Which approach would you recommend? Is there anything else I have to modify?

Thanks,

O’Tor