Twizza, just in case your ‘notify me’ is switched on, I did a new topic called “Some impedance theory”. There is also yet another thread on the subj from Riz you may want to read. Blimey, Chinese whispers.

Did enjoy that isobaric something. I tend to forget the importance of keeping the atmospheric pressure constant 😉 Must give up smoking.

do you mean wiring the + on one terminal of one speaker to the – on the next speaker and then on to the amp output? and then the – on the other terminal to the + on the next ? you should never do this unles you require a push/pull isobaric alignment, some dual driver sub-woofers require this, maybe bass could elaborate on this one? i think there is an out of phase series and paralell too.

do you mean in series or parralell?? have a look here:
http://www.colomar.com/Shavano/4x12wiring.html
i think there is every possibility of wiring a 4×12 here, watch out for your Ohms ratings, get it wrong and it could be expensive.