Sub with three 15" drivers?

[blake_mooney]

Is it possible to build a sub that has two active 15" drivers and one 15" passive radiator? Would the amp you use have to match the wattage level of the active 15" drivers combined, or seperate?

[richie00boy]

Not unless the passive had absolutely humongous excursion. More likely would be a system using 2x 15in passives and 1x 15in driver.

The amp power will depend on the specific implementation of a design, but if everything is optimised the power required will be the total power of the system, which is the sum of the drive units.

[blake_mooney]

Ah I see, thanks. How about a duel 15" active driver design? Would you recommend not using a passive radiator?

[Cal Weldon]

Blake,

One of the secrets to a good PR system is to not make the drone cones work too hard. Always make sure the potential of the drones is higher the the active, meaning consider a 1.5 to 1 ratio as a good starting point. I know in the old days there were lots of 1 to 1 ie: an 8" cone and 8" drone but you don't see much of that anymore and for good reasons. If you are considering a dual 15" system, consider using 2 18" passives or even 4 15"

But...by the time you have a dual 15 set up, you are often past the point of needing passives. If you need a little extra, try going ported. Argh, that hurts to say. I'm not a bass reflex kind of guy.