Newbie question about multiple woofers

[fourdegrees11]

This board seems to be full of very knowlegable people, I'm trying to increase my understanding of things so one day I can contribute. I understand that doubling the number of drivers gives a 3 db increase in sensitivity, and wiring them in parallel also gives a 3 db boost for 6 db total increase. BSC eats up this gain and you get a the single drivers claimed sensitivity in your room. Thats what I understand, now for the questions...

In the above senario is a full 6 db of BSC automatic, or can you still shape it to whatever amount you like (3-4 db)?

If you have two 4 ohm drivers and you wire them in series to get 8 ohms, how does this play out? Does the increase in impedance cancel out the surface area gain? A pair of 90 db 4 ohm drivers become 90 db 8 ohm drivers that still have to deal with BSC, or am I looking at this all wrong...

[minkuni]

You are on the right track. Two (identical) drivers in series will have the same voltage sensitivity as either driver alone since doubling the impedance cancels out the gain from the doubled cone area. The advantage of this setup is a reduced current load on the amplifier.

As for the baffle step questions doubling the number of drivers with a parallel or series connection does not change anything. Connecting two bass drivers in parallel gives you 6dB higher voltage sensitivity which you can choose to spend entirely on BSC, but only if you want to. In many cases a full 6dB is not required (or desired) and you can get away with 3-4dB of BSC with a couple of dB's "left over" to spend on midrange/tweeter sensitivity. I hope this makes sense to you

[fourdegrees11]

Thanks!