i know ive heard that surface area and excursion effects spl. but how much? right now i have 4 12" kicker cvr in a sealed box. I was thinking about switching to a bandpass box anyway because they are better for spl. but i did some math and i figured that 4 12" subs have more surface area than 2 15" subs. for some reason though all of my friends say that 2 15" would be louder than 4 12". im not sure how big of a difference the xmax is between the two. the amplifier i have is a jbl 1200.1. so either setup would get 1200 watts rms.
here are my questions. would 2 15" be louder than 4 12"? would a bandpass box make that big of a difference? (all i listen to is rap anyway) what would be the loudest setup? i.e. any size, any box.
your friends are incorrect. sound pressure is made by speakers moving air. The more air you move, the more volume you're going to get. That's done by a combination of excursion, and surface area.. four twelves will move more air with equal Xmax to the two fifteens. Now, fifteens usually have greater Xmax so that's something to figure as well. If all you want is SPL then think about a 6th order box. a 4th order will give you about +6dB over a sealed box, which is a big difference, but it's not going to hit nearly as deeply as sealed or ported.. just louder.
j-dub dub
Unregistered guest
Posted on
thanks.
about how low will the 4th order box go? im assuming they can be tuned differently, but on average what are the lowest and highest frequencies a 4th order box will play?
j-dub dub
Unregistered guest
Posted on
i found out the xmax for both models. the cvr12 has xmax of 11.5 mm. the cvr15 has xmax of 12.75 mm. i converted mm to in by dividing by 25.4. i then multiplied the surface area by xmax to find the amount of air it moves. (even though the speaker is conic and not cylindrical. i assume it will be close enough)
so i figure 4 12" will displace about 205 cubic inches of air, and the 2 15" will only displace about 177 cubic inches of air. does this sound about right?
as for tuning, a 4th order usually is peak efficient between about 45Hz and 120Hz. You can tune them to your tastes, but generally tuning them low, you lose any advantage you would gain in SPL/efficiency. At that point, ya may as well go straight ported.
