It should be about 90-100 cms deep and open up at 2100-2300cms I believe. That should do it according to the hornresponse program. Seems like it might be hard to find a woofer that will give you reallysmooth (mid)bass response though. I'm still debating wether to try one or use a pi mid(it seems much easier to get a smooth low-end with that. Sorry, that's the best I can give you.